s
Percutaneous coronary intervention in acute myocardial infarction: from
procedural considerations to long term outcomes
Delewi, R.
Publication date
2015
Document Version
Final published version
Link to publication
Citation for published version (APA):
Delewi, R. (2015). Percutaneous coronary intervention in acute myocardial infarction: from
procedural considerations to long term outcomes. Boxpress.
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Percutaneous coronary intervention
in acute myocardial infarction:
from procedural considerations to long term outcomes
Ronak Delewi
P
ercutaneous coronar
y inter
vention
in acute m
yocardial infarction
R
onak Dele
wi
Uitnodiging
Voor het bijwonen van de openbare verdediging van het proefschrift
Percutaneous coronary intervention in acute myocardial infarction: from procedural considerations to long
term outcomes door Ronak Delewi Op woensdag 13 mei 2015 Om 14:00 in de Agnietenkapel Oudezijds Voorburgwal 231 Amsterdam
Receptie na afloop van de verdediging in Hotel The Grand
Oudezijds Voorburgwal 197 Amsterdam Paranimfen Anne Gubser 06-28251371 annegubser@gmail.com Mariella Hassell 06-46786617 m.e.hassell@amc.nl
from procedural considerations to long term outcomes
from procedural considerations to long term outcomes
Thesis, University of Amsterdam ISBN: 978-94-6295-168-6
Author: Ronak Delewi
Artwork cover: Carien van den Honert
Printed by: Proefschriftmaken.nl || Uitgeverij BOXPress Published by: Proefschriftmaken.nl || Uitgeverij BOXPress
The research described in this thesis was supported by a grant of the Dutch Heart Foundation (Grant number NHS-2011T022) and the National Health Insurance Board/ ZON MW (grant number 40-00703-98-11629). Moreover, this work was supported by the Netherlands Heart Institute (ICIN).
Financial support by the Dutch Heart foundation for the publication of this thesis is gratefully acknowledged.
Generous support by Osprey Medical Inc. and Svelte Medical Systems for the publication of this thesis is gratefully acknowledged.
Financial support for printing this thesis was provided by the University of Amsterdam, Abbott Vascular, Bayer Health Care, Biotronik, Chipsoft, Guerbet Nederland B.V., Pfizer, Sigma medical, Servier Nederland Farma B.V., St. Jude Medical, Stentys.
Copyright © 2015 Ronak Delewi, Amsterdam, the Netherlands. No parts of this thesis may be reproduced or transmitted in any form or by any means, without the prior permission of the author.
from procedural considerations to long term outcomes
ACADEMISCH PROEFSCHRIFT
ter verkrijging van de graad van doctor aan de Universiteit van Amsterdam op gezag van de Rector Magnificus
prof. dr. D.C. van den Boom
ten overstaan van een door het College voor Promoties ingestelde commissie, in het openbaar te verdedigen in de Agnietenkapel
op woensdag 13 mei 2015, te 14:00 uur
door Ronak Delewi geboren te Naarden
Promotores: prof. dr. J.J. Piek prof. dr. F. Zijlstra Co-promotores: prof. dr. J.G.P. Tijssen
dr. A. Hirsch
Overige leden: prof. dr. J.B.L. Hoekstra prof. dr. S. Janssens prof. dr. C.B.L.M. Majoie prof. dr. R.J.G. Peters prof. dr. Y.M. Pinto prof. dr. A.H. Zwinderman
Het onderzoek dat aan dit proefschrift ten grondslag ligt, is mogelijk gemaakt door een subsidie van de Nederlandse Hartstichting (NHS-2011 T022) en ZorgOnderzoek Nederland - Medische Wetenschappen (ZON MW, 40-00703-98-11629).
Part I General Introduction 11
Part II Complications and radiation exposure
Chapter 1 Radiation exposure during percutaneous coronary
interventions and coronary angiograms performed by the radial compared with the femoral route. JACC Cardiovascular
interventions. 2012;5:752-7 17
Chapter 2 Clinical and procedural characteristics associated with higher
radiation exposure during percutaneous coronary interventions and coronary angiography. Circulation Cardiovascular
interventions. 2013;6:501-6. 31
Chapter 3 Silent cerebral infarcts associated with cardiac disease and
procedures. Nature reviews Cardiology. 2013;10:696-706. 47
Chapter 4 Prognostic value of access site and nonaccess site bleeding
after percutaneous coronary intervention: a cohort study in ST-segment elevation myocardial infarction and comprehensive
meta-analysis. JACC Cardiovascular interventions. 2014;7:622-30. 75
Part III Natural course and left ventricular remodeling
Chapter 5 Monocyte subset accumulation in the human heart following
acute myocardial infarction and the role of the spleen as
monocyte reservoir. European heart journal. 2014;35:376-85. 101
Chapter 6 Myocardial infarct heterogeneity assessment by late
gadolinium enhancement cardiovascular magnetic resonance imaging shows predictive value for ventricular arrhythmia development after acute myocardial infarction. European heart
journal Cardiovascular imaging. 2013;14:1150-8. 121
Chapter 7 Left ventricular thrombus formation after acute myocardial
infarction as assessed by cardiovascular magnetic resonance
imaging. European journal of radiology. 2012;81:3900-4. 143
Chapter 8 Left ventricular thrombus formation after acute myocardial
segment elevation myocardial infarction as assessed by cardiac
magnetic resonance imaging. Submitted. 179
Chapter 10 Pathological Q waves in myocardial infarction in patients
treated by primary PCI. JACC Cardiovascular imaging.
2013;6:324-31. 195
Part IV Intracoronary bone marrow cell therapy
Chapter 11 Long term outcome after mononuclear bone marrow or
peripheral blood cells infusion after myocardial infarction.
Heart. 2015;101:363-8. 213
Chapter 12 Impact of intracoronary cell therapy on left ventricular
function in the setting of acute myocardial infarction: a meta-analysis of randomised controlled clinical trials.
Heart. 2013;99:225-232. 229
Chapter 13 Comment to “Adult bone marrow cell therapy improves
survival and induces long-term improvement in cardiac parameters: a systematic review and meta-analysis”.
Circulation. 2013;127:e547. 257
Chapter 14 Impact of intracoronary bone marrow cell therapy on left
ventricular function in the setting of ST-segment elevation myocardial infarction: a collaborative meta-analysis. European
heart journal. 2014;35:989-98. 261
Part V Summaries and future perspectives
English Summary 284 Nederlandse Samenvatting 288 Part VI Appendices List of abbreviations 295 Curriculum Vitae 297 List of publications 299 Dankwoord 305
GENERAl INTRODUCTION
Patients presenting with AMI are treated with primary percutaneous coronary intervention (PCI). Across the broad spectrum of patients with acute myocardial infarction (AMI), short-term (in-hospital or 30-day) mortality has decreased dramatically over the past 30 years, concomitantly with the increasing use of mechanical reperfusion by PCI and pharmacological therapies such as beta blockers, angiotensin-converting-enzyme (ACE)-inhibitors and statins. The current in-hospital mortality of ST-elevation myocardial infarction (STEMI) is below 5%.1 However, morbidity is still high due to peri-procedural events as well as events that occur during the natural course of infarct healing.
A devastating complication of PCI is ischaemic stroke which occurs in 0.07% to 1.3% of patients undergoing a PCI procedure.2 However, the frequency of silent cerebral infarction is much higher, ranging from 2% to 35%.3-5 Moreover, bleeding complications after PCI are associated with an increased risk of mortality and morbidity.6 Therefore, considerable effort has been made to develop novel treatment strategies directed at minimizing bleeding complications. One such strategy, performing PCI via the radial artery, has been shown in prospective, randomized trials to result in a reduction in bleeding complications arising at the arterial puncture site.7 Unfortunately, although access site bleeding represents a common source of bleeding in patients undergoing PCI, as many as 50% to 60% of major and minor bleeding complications are not related to the arterial access.8 Moreover, there have been concerns regarding the possible increase in radiation exposure for patients when the radial artery is used as an access site.
After the performance of primary PCI during the acute phase of myocardial infarction, an adequate healing response is pivotal for preserving left ventricular (LV) function and geometry. The initial post-MI phase includes fibrotic repair of the necrotic area with scar formation with subsequent elongation and thinning of the infarct zone. During this initial phase, myocyte necrosis, edema and inflammation are localized to the infarcted region. This complex and dynamic process of infarct healing is critically mediated by monocytes, that may lead after uncontrolled monocyte response to impaired post-AMI healing.9
Adequate post-AMI healing is crucial for the prevention of adverse left ventricular remodeling. Adverse left ventricular remodeling refers to alterations in ventricular architecture involving both the infarcted and non-infarcted zones leading to progressive increase in systolic and diastolic left ventricular volumes. This increase of LV volumes can be considered adaptive as it is an attempt to augment stroke volume and to maintain cardiac output. However, in patients with progressive post-infarction dilation, the end-systolic volume index increases progressively and LV ejection fraction (LVEF) declines.
These changes are important predictors of mortality.10 Also, in these patients there is a risk of left ventricular thrombus formation and subsequent thromboembolic complications. The magnitude of adverse remodelling and subsequent mortality is related to infarct size and the presence of microvascular injury. Cardiac magnetic resonance (CMR) is considered the non-invasive standard for these parameters as it provides a detailed evaluation of cardiac function and anatomy. Contrast-enhanced CMR with late gadolinium enhancement allows assessment of myocardial viability and transmural extent of viable myocardium providing the potential to identify those patients who are at highest risk for adverse remodeling.
Moreover, CMR enables the determination of the size of the infarct’s surrounding border zone, the so-called penumbra. This area consists of a heterogeneous mass of necrotic, ischemic and viable myocardium, as well as edema and fibroblasts which hypothetically provides a substrate for the development of ventricular arrhythmias.
Beyond the acute phase of myocardial infarction, CMR can monitor the process of long term left ventricular remodeling. There is accumulating evidence that left ventricular remodeling is a dynamic process occurring not only in the first weeks to months after myocardial infarction, but also in the long period thereafter. Pathological Q waves on the electrocardiogram are considered the classic ECG sign of necrosis, but these Q waves may partially or completely disappear during the evolution of myocardial infarction. CMR can be used to analyze whether such Q-wave regression is related to shrinkage in infarct size and/or improvement of LV function.
However, the ultimate goal is reversal or attenuation of adverse LV remodeling with therapeutic interventions in addition to standard pharmacotherapeutic regimens. Bone marrow cells have the capacity to proliferate, migrate, and also differentiate into various mature cell types. It therefore has the potential for tissue repair. Animal studies demonstrated a beneficial effect of local administration of progenitor cells.11 Several clinical trials rapidly followed to translate these exciting preclinical results with the aim to prevent deterioration of LV ventricular function and thereby reducing the large burden of heart failure.
REFERENCES
1. Sugiyama T, Hasegawa K, Kobayashi Y, Takahashi O, Fukui T, Tsugawa Y. Differential time trends of outcomes and costs of care for acute myocardial infarction hospitalizations by st elevation and type of intervention in the united states, 2001-2011. Journal of the American Heart Association. 2015;4
2. Guptill JT, Mehta RH, Armstrong PW, Horton J, Laskowitz D, James S, et al. Stroke after primary percutaneous coronary intervention in patients with st-segment elevation myocardial infarction: Timing, characteristics, and clinical outcomes. Circulation. Cardiovascular interventions. 2013;6:176-183
3. Murai M, Hazui H, Sugie A, Hoshiga M, Negoro N, Muraoka H, et al. Asymptomatic acute ischemic stroke after primary percutaneous coronary intervention in patients with acute coronary syndrome might be caused mainly by manipulating catheters or devices in the ascending aorta, regardless of the approach to the coronary artery. Circulation journal : official journal of the Japanese Circulation Society. 2008;72:51-55
4. Busing KA, Schulte-Sasse C, Fluchter S, Suselbeck T, Haase KK, Neff W, et al. Cerebral infarction: Incidence and risk factors after diagnostic and interventional cardiac catheterization--prospective evaluation at diffusion-weighted mr imaging. Radiology. 2005;235:177-183
5. Omran H, Schmidt H, Hackenbroch M, Illien S, Bernhardt P, von der Recke G, et al. Silent and apparent cerebral embolism after retrograde catheterisation of the aortic valve in valvular stenosis: A prospective, randomised study. Lancet. 2003;361:1241-1246
6. Kwok CS, Rao SV, Myint PK, Keavney B, Nolan J, Ludman PF, et al. Major bleeding after percutaneous coronary intervention and risk of subsequent mortality: A systematic review and meta-analysis. Open heart. 2014;1:e000021
7. Jolly SS, Yusuf S, Cairns J, Niemela K, Xavier D, Widimsky P, et al. Radial versus femoral access for coronary angiography and intervention in patients with acute coronary syndromes (rival): A randomised, parallel group, multicentre trial. Lancet. 2011;377:1409-1420
8. Verheugt FW, Steinhubl SR, Hamon M, Darius H, Steg PG, Valgimigli M, et al. Incidence, prognostic impact, and influence of antithrombotic therapy on access and nonaccess site bleeding in percutaneous coronary intervention. JACC. Cardiovascular interventions. 2011;4:191-197
9. Hilgendorf I, Gerhardt LM, Tan TC, Winter C, Holderried TA, Chousterman BG, et al. Ly-6chigh monocytes depend on nr4a1 to balance both inflammatory and reparative phases in the infarcted myocardium. Circulation research. 2014;114:1611-1622
10. Spinelli L, Morisco C, Assante di Panzillo E, Izzo R, Trimarco B. Reverse left ventricular remodeling after acute myocardial infarction: The prognostic impact of left ventricular global torsion. The international journal of cardiovascular imaging. 2013;29:787-795
11. Tomita S, Li RK, Weisel RD, Mickle DA, Kim EJ, Sakai T, et al. Autologous transplantation of bone marrow cells improves damaged heart function. Circulation. 1999;100:II247-256
1
Chapter 1
Radiation exposure during percutaneous coronary
interventions and coronary angiograms performed by the
radial compared with the femoral route
Ronak Delewi,* Gerritjan Kuipers,* Xandra L. Velders, Marije M. Vis, Rene J. van der Schaaf, Karel T. Koch, José P. S. Henriques, Robbert J. de Winter, Jan Baan Jr, Jan G. P. Tijssen, Jan J. Piek
*Both authors contributed equally
ABSTRACT
Objectives This study aimed to compare radiation exposure of patients undergoing
percutaneous coronary interventions (PCI) and coronary angiograms (CAG) accessed by the femoral route with the radial route (operator’s choice).
Background There are limited and contradictory data on the radiation exposure of
patients during PCI and CAG performed by the radial route compared with the femoral route.
Methods Data on the radiation exposure of patients from 3,973 PCI and CAG
procedures between June 22, 2004, and December 31, 2008, were prospectively collected and analyzed. A prediction model was made for radiation exposure (dose-area product in Gy·cm2) based upon the femoral access group, and the group of radial performed procedures was compared to assess differences between observed and expected radiation exposure.
Results Median exposures of patients undergoing a PCI via the femoral route (n= 2,309)
was 75 (interquartile range [IQR]: 44 to 135) Gy·cm2 compared with 72 (IQR: 42 to 134) Gy·cm2 for radial performed procedures (n= 1,212) (p=0.30). Median exposure for CAGs was 44 (IQR: 31 to 69) Gy·cm2 and 40 (IQR: 25 to 65) Gy·cm2 for, respectively, femoral (n= 314) and radial performed procedures (n=138), (p=0.31). Also, the observed radiation exposure in patients undergoing radial PCI or CAGs was not higher than the expected exposure of patients as predicted by the femoral access based prediction model (71.5 ± 2.3 Gy·cm2 vs. 79.9 ± 1.8 Gy·cm2,).
Conclusions The study shows that even after correction for the complexity of the
procedures, selected procedures performed by the radial route are not associated with higher radiation exposure of patients than selected procedures performed by the femoral route.
1
INTRODUCTION
The femoral route has traditionally been the preferred access site for percutaneous coronary interventions (PCIs) and coronary angiograms (CAGs). In 1989, the radial route was first introduced, and since then, the number of procedures performed by the radial route increased as the technique evolved with improvement in catheter design and with interventional cardiologists’ experience.1 Advantages of the radial access route include less bleeding and fewer vascular complications, whereas the success rate is similar compared with procedures performed by the femoral route.2
The radiation exposure during fluoroscopy-guided procedures became a topic of concern as the number of procedures increased during the years. In Publication 85 of the International Commission on Radiological Protection (ICRP),3 the risks of radiation exposure from fluoroscopy-guided procedures are described. The ICRP reported an increase of radiation-induced injuries to patient’s skin (deterministic effect) as well as the risk to develop radiation-induced cancers (stochastic effect).
Over the years, contradictory results were reported on the radiation exposure of patients from procedures performed by the radial route.4–8 In the present study, we report radiation exposure data of a large, real-world patient population undergoing routine PCI or CAG. The aim of the study was to compare radiation exposure of patients during PCI and CAG accessed by either the radial or the femoral route.
METHODS
Setting
This study used data that were prospectively collected between 2004 and 2008 as part of a local cardiac catheterization registry at a high-volume tertiary cardiac care center in Amsterdam, the Netherlands. Over 2,000 PCIs and 1,200 CAGs are performed at this center each year. The center is a teaching institution, and procedures are routinely performed by a staff interventional cardiologist alone, or together with an interventional fellow-in-training.
There were 6 interventional cardiologists working within the unit during the entire observation period, with experience in both the radial and femoral approaches. In the study period, all operators performed at least 800 procedures using a femoral access site and 200 procedures using a radial access site. Radial approach was right sided. At PCI or CAG, the patient-specific data were entered into an electronic database by qualified catheterization laboratory personnel and interventional cardiologists. Patient variables included clinical (i.e., age, risk factors, sex, and cardiac history), angiographic, and procedural characteristics (i.e., number of stents implanted, type of lesion).
Patient population
Our present study included all patients in the Academic Medical Center who had undergone PCI or CAG between June 22, 2004, and December 31, 2008. In general, patients treated using the femoral approach were excluded: 1) patients were referred for an emergency PCI (e.g., rescue or primary for ST-segment elevation myocardial infarction) or procedures for noncoronary interventions; 2) patients had a history of coronary artery bypass graft (CABG); and 3) patients had a chronic total occlusion or more than 2 bifurcated lesions. A bifurcated lesion was defined as ≥50% narrowing of the vessel diameter involving both the main and side branch, based on visual assessment on the angiogram as assessed by the operator. PCIs and CAGs were performed using standard techniques. Patients in whom PCI was performed have been classified as such. This rule also applied to patients who went for CAG with the option of PCI. All patients were treated with heparin and aspirin before PCI. All procedural decisions, including device selection and adjunctive pharmacotherapy, were made at the discretion of the operator. For this analysis, we only included procedures performed by a licensed interventional cardiologist.
1
Dose-area product values and catheterization laboratory equipment
The radiation exposure of patients undergoing PCI and CAG was measured using dose-area product (DAP) meters. The DAP is the product of the dose value of the incident radiation and the irradiated field size and is expressed in Gy·cm2. The DAP meters (Diamentor, PTW-Freiburg, Germany/KermaX-plus, Wellhöfer, Germany) were integrated in the X-ray systems. The X-ray systems provided direct feedback of the radiation exposure on the monitor of the systems. The radiation exposure from fluoroscopy mode and cine mode as well as the total radiation exposure (fluoroscopic mode and cine mode) was displayed on the monitor of the X-ray systems. Moreover, the fluoroscopy time (in minutes) was displayed on the monitor. The DAP meters were calibrated at regular intervals with a reference dosimeter (Unforce Xi, Bildall, Sweden). The DAP values as well as the fluoroscopy time were entered into a dedicated electronic database that was linked to the catheterization registry database.
The procedures were carried out in 3 different catheterization rooms. The catheterization rooms were equipped with Philips X-ray systems (Philips Medical Systems, Best, the Netherlands). Two Integris H5000 systems, and an Allura 9C flat panel system were used with field of views of 25-, 19-, and 15-cm diagonal square. The entrance exposure rate in the fluoroscopy mode of the X-ray systems varied between 40 mGy·min-1 in the low-dose mode up to 80 and 160 mGy·min-1 in the normal- and high-dose modes. The inherent filtration of the X-ray systems was 2.4 mm Al equivalent. In the low- and normal-dose modes, additional filters of 0.4 mm Cu and 0.1 mm Cu, respectively, were automatically added. In the high fluoroscopy mode and in the cine mode, no additional filters were inserted. All X-ray systems used 25 pulse·s-1 in the normal- and high-dose modes. In the low-dose mode, the pulse rate for the Allura 9C was 12.5 pulse·s-1, whereas for the Integris H5000, the pulse rate was continuously adjusted. In the cine mode, the number of frames was variable: either 12.5 frames·s-1 or 25 frames·s-1.
The interventional cardiologists used lead aprons and thyroid collars of 0.50-mm lead equivalent thickness at 100 kVp (Medical Development and Technology BV, Hilvarenbeek, the Netherlands). Furthermore, the interventional cardiologists used ceiling-mounted lead glass screens (Pb equivalent: 0.50 mm, MAVIG, Munich, Germany) and table shield systems (Pb equivalent: 0.50 mm, Kenex (Electro-Medical), Harlow, United Kingdom).
Statistical analyses
We compared DAP values of procedures accessed by the femoral route with those of the radial route by Mann-Whitney U test. To reduce the effect of selection bias and potential confounding of all clinical and procedural characteristics in this observational study, we made a prediction model for the natural logarithm (Ln) of the radiation exposure based upon the femoral access group because the distribution of the DAP
values were positively skewed. We then compared the geometric mean to the group of radial performed procedures to assess differences between observed and expected radiation exposure. Clinical and procedural characteristics were described by category of access route. Continuous variables were expressed as mean and standard deviation. Differences between groups were assessed by unpaired Student t test or Mann-Whitney
U test as appropriate. Categorical variables were expressed as count and percentage, and
were tested with the chi-square test or Fisher exact test, as appropriate. Covariates of interest as predictors of radiation were investigated using multivariable linear regression. Baseline variables that were significant at p≤0.10 on univariate analysis were entered into a multivariate model. The prediction model was used to correct for differences in patient and procedural characteristics treated by the radial and femoral routes. Statistics were performed with SPSS version 18.0.1 (Chicago, Illinois). Statistical significance was considered as p value <0.05.
RESUlTS
Patients
The total number of procedures included in the present study is 2,623 for procedures performed by the femoral route and 1,350 for procedures performed by the radial route. In total, 10,905 PCI and CAG procedures were performed during the study period. Excluded procedures were procedures performed by a fellow in training (n=1,217), emergency PCIs (n=2,985), patients with a history of CABG (n = 670), chronic total occlusion (n=424), and patients with more than 2 bifurcated lesions (n =760). Radiation exposure data were not available for 876 patients. Clinical and angiographic of patients with missing radiation exposure data were comparable to the study population (data not shown). In Table 1, patient and procedure characteristics are shown, stratified by access route.
Median DAP value was 69 (interquartile range [IQR]: 40 to 126) Gy·cm2 for femoral performed procedures compared with 69 (IQR: 40 to 128) Gy·cm2 for procedures performed via the radial route (p=0.76). Median fluoroscopy time was 12.4 (IQR: 7.4 to 20.6) min versus 11.0 (IQR: 6.9 to 18.2) min for, respectively, the femoral and radial access routes (p <0.001). Median radiation exposures of the patients undergoing a PCI via the femoral route (n=2,309) was 75 (IQR: 44 to 135) Gy·cm2 compared with 72 (IQR: 42 to 134) Gy·cm2 for radial performed procedures (n=1,212) (p=0.30). The median exposure for CAGs was 44 (IQR: 31 to 69) Gy·cm2 and 40 (IQR: 25 to 65) Gy·cm2 for, respectively, femoral (n=314) and radial performed procedures (n=138) (p=0.31).
1
Table 1. Patient and procedural characteristics by category of access routeBaseline characteristic Femoral routeN = 2623 Radial RouteN = 1350 P-value
Age (years) 63 ± 9 64 ± 11 0.03
Male gender 69% 74% 0.001
Body mass index (kg/m2) 27 ± 4 27 ± 4 0.66
Diabetes mellitus 20% 21% 0.93
Known hypertension 47% 50% 0.12
Family history of coronary heart disease 54% 47% 0.47
Hypercholesterolemia 42% 40% 0.15
Current cigarette smoking 24% 23% 0.38
History of PCI 35% 39% 0.35
Use of Vitamin K antagonist 3% 5% 0.001
Multivessel disease 31% 28% 0.04
Date of CAG or PCI
Jul.2004–Dec.2005 40% 10% <0.001 Jan.2006–Jun.2007 37% 36% 0.49 Jul.2007–Dec.2008 23% 54% <0.001 Operator 1 17% 11% <0.001 2 17% 17% 0.77 3 20% 36% <0.001 4 22% 13% <0.001 5 14% 14% 0.96 6 10% 10% 0.55 CAG 12% 10% 0.10 PCI
No. of lesions treated per PCI
1 68% 68% 0.65 2 25% 25% 1.00 3 6% 6% 0.65 Location of lesion LAD 51% 52% 0.44 RCX 33% 33% 0.58 RCA4 35% 36% 0.37 Lesion Type A 8% 8% 0.28 B1 28% 28% 0.84 B2 33% 37% 0.045 C 26% 19% <0.001 Lesion calcification 30% 27% <0.01
Proximal coronary vessel tortuosity 8% 8% 0.79
Post dilatation 49% 49% 0.83
Thrombus aspiration 2% 2% 0.25
Bifurcation lesion 11% 10% 0.06
Fluoroscopy time (in minutes) 12.4 (7.4 - 20.6) 11.0 (6.9 – 18.2) <0.001
Allura imaging system 52% 60% <0.001
CAG = coronair angiogram, LAD = left anterior descending artery, PCI = percutaneous coronary interventions, RCA= right coronary artery, RCX= left circumflex artery
The results of the multiple regression analysis from procedures performed by the femoral route are shown in Table 2. Multivariate predictors of radiation exposure were male sex, body mass index, number of lesions, type C lesions, right coronary artery lesions, left circumflex coronary lesions, and type of imaging system. Moreover, each interventional cardiologist was considered as a predictor for the radiation exposure.
Table 2 Multivariate analysis of predictors of radiation exposure (LnDAP) performed by the
femoral route
Predictor B SE Exp B P-value
Intercept 2.78 0.097 16.11 0.001
Male 0.26 0.028 1.30 <0.001
Body mass index (kg/m2) 0.05 0.003 1.05 <0.001
No. of lesions treated 0.24 0.022 1.27 <0.001
Type C lesion 0.48 0.031 1.62 <0.001
Location of lesion:
Right coronary artery 0.17 0.025 1.18 <0.001
Left circumflex artery 0.12 0.027 1.12 <0.001
Operator 1* -0.62 0.044 -1.86 <0.001
Operator 2* -0.79 0.043 -2.20 <0.001
Operator 4* -0.36 0.04 -1.44 <0.001
Operator 5* -0.33 0.047 -1.39 <0.001
Operator 6* -0.06 0.04 -1.06 0.007
Allura imaging system Ψ 0.24 0.027 1.27 <0.001
LnDAP = natural logarithm of the dose-area product. *Relative to operator 3 (reference). Operator was the most experience operator, with the highest volume. Operator 3 was also the operator with the highest radiation exposure. Ψ Relative to Integris imaging system.
In Table 3, the results of the expected radiation exposures based upon the prediction model derived in the femoral access group was compared with the observed radiation exposures of procedures accessed via the radial route. The observed radiation exposure in patients undergoing radial PCIs or CAGs was not higher than the expected exposure of patients as predicted by the femoral access-based prediction model (71.5 ± 2.3 Gy·cm2 vs. 79.8 ± 1.8 Gy·cm2 [geometric mean]).
Table 3 also shows decreased radiation exposure with increased operator experience (88.2 ± 2.4 Gy·cm2 in 2004 to 2005 vs. 66.2 ± 2.3 Gy·cm2 in 2007 to 2008, [geometric mean]).
1
DISCUSSION
In our study, the exposure of patients did not differ between procedures performed by the radial route or the femoral route. The median exposure was 69 Gy·cm2 both in procedures performed by the radial route and by the femoral route (PCI and CAG). Even after correction for complexity of the procedures, selected procedures via the radial route are not associated with higher radiation exposure for patients than selected procedures via the femoral route.
In Table 4, radiation exposure levels of patients reported by previous studies are shown.4-8 Sandborg et al.4 reported higher exposure of patients from procedures performed by the radial route than procedures performed by the femoral route for both PCIs and CAGs. In their study, the interventional cardiologists were experienced in performing the procedures by the femoral route, whereas the radial route was used as a complementary technique to the femoral route. Lange et al.5 reported higher exposure of patients for CAG procedures assessed by the radial route, whereas for PCI procedures, the exposure did not differ between both access routes. The higher exposure for CAGs performed by the radial route was explained by a higher fluoroscopy time due to difficulties in advancing the catheter across the aortic arch. Brasselet et al.6 reported the exposure of patients for CAGs and PCIs. They found higher exposure of patients from procedures performed by the radial route. However, the results reported in their study were biased because the mean body weight of the group of patients treated by the femoral route was lower compared with the mean body weight of the group of patients that underwent the procedures by the radial route. The findings in the present study were comparable to the findings reported by Geijer et al.7 They reported radiation exposure of patients for PCIs. They reported radiation exposure of patients for PCIs and concluded that the exposure of patients does not increase when using the radial access route. Mercuri et al.8
Table 3 Geometric mean of observed and expected DAP (in Gy·cm2) of procedures performed
by the radial route
N
Geometric mean of DAP Observed
(Gy·cm2) Expected(Gy·cm2) Observed-Expected(Gy·cm2)
Overall 1350 71.5 ± 2.3 79.8±1.8 -8.3 ± 1.9 Date of PCI July 2004 – Dec. 2005 135 88.2 ± 2.4 110.0 ± 1.8 -21.8 ± 2.0 Jan. 2006– June 2007 482 74.4 ± 2.3 80.6 ± 1.8 -6.2 ± 1.8 July 2007– Dec. 2008 733 66.6 ± 2.3 75.2 ± 1.8 -8.6 ± 1.8 Age < 65 years 625 72.9 ± 2.3 83.1 ± 1.8 -10.2 ± 1.8
Body mass index < 29 kg/m2 382 91.8 ± 2.2 105.5 ± 1.7 -13.7 ± 1.8
Lesion Type C 255 134.3 ± 2.1 148.4 ± 1.6 -14.1 ± 1.9
reported about the air kerma (in Gy) as a measure for radiation exposure of patients. They reported higher exposures of patients from procedures accessed by the radial route compared with the femoral route. However, estimations of effective doses 9 of patients using DAP measurements may be more accurate than using air kerma measurements, as DAP allows for variations in field size.10 The RIVAL (RadIal Vs femorAL access for coronary intervention) study was a large randomized trial comparing radial and femoral access for coronary angiography and intervention.11 Duration of fluoroscopy was higher in the radial access group, 9.3 (5.8 to 15) min compared with 8.0 (4.5 to 13) min in the femoral access group. However, the authors did not directly measure radiation exposure. Moreover, the average annual operator’s volume was relatively low compared with our high-volume center. As our data suggest, increased radiation exposure decreases with increasing experience.
In the present study, data on the radiation exposure of patients undergoing routinely performed PCI or CAG were reported. All data included in the study were from procedures performed in a tertiary primary PCI center by interventional cardiologists with extensive experience in performing procedures by the radial and the femoral route. In the multiple regression analysis, each interventional cardiologist is described as a predictor of the exposure of the patients. It is likely that the mode of operation contributed to the variation in exposure of the patients. Since the interventional cardiologists in the department have different preferences regarding the use of the cine mode and the 3 different fluoroscopy modes, the mode of operation is responsible for the variation in exposure of patients. It is also possible that differences in distance to the patients during exposures, such as the position of the X-ray tube, the height of the table, and the distance between patient and image intensifier during the procedures, contributed to the variation in patients’ exposure. We did not measure these variables, and it is uncertain to what extend the variation in the model is caused by these variables. Moreover, the radiation exposure of the interventional cardiologists was not measured in the present
Table 4 Radiation exposure of patients stratified by PCIs and CAGs reported in earlier studies
Author PCI CAG
Femoral access Radial access
P
Femoral access Radial access
P
N (Gy·cmDAP2) N (Gy·cmDAP2) N (Gy·cmDAP 2) N (Gy·cmDAP 2)
Present study 2,309 75 1212 72 NS 314 44 138 40 NS
Sandborg et al.4 42 47 24 75 < 0.05 40 38 36 51 < 0.05
Lange et al.5 48 51 54 46 NS 103 13 92 15 < 0.05
Brasselet et al.6 83 103 90 126 < 0.05 98 38 150 59 < 0.05
Geijer et al.7 114 70 55 71 NS - - - -
-NS=non significant. CAG; coronair angiogram, DAP; Dose Area Product, PCI; Percutaneous Coronary Interventions
1
study. During interventional procedures performed by the radial route, the interventional cardiologists are usually closer to patients than during procedures performed by the femoral route. Since the intensity of scattered radiation close to patients is higher than the intensity at greater distances, it is possible that the radiation exposure of interventional cardiologists from procedures performed by the radial route is higher compared with the exposure from procedures performed by the femoral route. However, in a previous study 12, a linear relation was found between the exposure of monthly measurements measured outside the lead aprons of the interventional cardiologists and the exposure of patients, irrespective of the interventional cardiologists or number of performed radial/femoral procedures.
The procedures in the study were performed at a high-volume center by interventional cardiologists with extensive experience in performing procedures by the radial and the femoral routes. Therefore, our results can only be applied to centers where procedures are performed by interventional cardiologists with sufficient experience in both the femoral and the radial routes. Also, we do not have data on conversion from radial access to femoral access sites. It is not known to what extend the results can be applied to other centers where the radial route is used as a complementary technique to the femoral route, and interventional cardiologists are less experienced in performing procedures by the radial route.
Study limitations
This is an observational study in which patients were selected for radial or femoral access, quite likely based on the operators’ perception of technical difficulty and procedural duration associated with one approach versus the other. With technical difficulty being strongly associated with radiation exposure, it can be expected that the selection process greatly influenced the radiation exposure results.
CONClUSIONS
The study shows that even after correction for the complexity of the procedures, selected procedures performed by the radial route are not associated with higher radiation exposure of patients than selected procedures performed by the femoral route.
REFERENCES
1. Campeau L. Percutaneous radial artery approach for coronary angiography. Cathet Cardiovasc Diagn 1989;16:3–7.
2. Rao SV, Ou FS, Wang TY, Roe MT, Brindis R, Rumsfeld JS, Peterson ED. Trends in the prevalence and outcomes of radial and femoral approaches to percutaneous coronary intervention: a report from the national cardiovascular data registry. JACC Cardiovascular interventions. 2008;1:379–86.
3. International Commission on Radiological Protection. Avoidance of Radiation Injuries from Medical Interventional Procedures. Publication 85. Oxford: Pergamon Press; 2000.
4. Sandborg M, Fransson SG, Pettersson H. Evaluation of patient-absorbed doses during coronary angiography and intervention by femoral and radial artery access. Eur Radiol. 2004;14:653–658.
5. Lange HW, von Boetticher H. Randomized comparison of operator radiation exposure during coronary angiography and intervention by radial or femoral approach. Catheter Cardiovasc Interv. 2006;67:12–16.
6. Brasselet C, Blanpain T, Tassan-Mangina S, Deschildre A, Duval S, Vitry F, Gaillot-Petit N, Clément JP, Metz D. Comparison of operator radiation exposure with optimized radiation protection devices during coronary angiograms and ad hoc percutaneous coronary interventions by radial and femoral routes. Eur Heart J. 2008;29:63–70.
7. Geijer H, Persliden J. Radiation exposure and patient experience during percutaneous coronary intervention using radial and femoral artery access. Eur Radiol. 2004;14:1674– 1680.
8. Mercuri M, Mehta S, Xie C, Valettas N, Velianou JL, Natarajan MK. Radial artery access as a predictor of increased radiation exposure during a diagnostic cardiac catheterization procedure. JACC Cardiovascular interventions. 2011;4:347–352.
9. International Commission on Radiological Protection. Recommendations of the International Commission on Radiological Protection. ICRP Publication 60. Oxford, UK: Pergamon Press, 1990.
10. Bor D, Sancak T, Olgar T, Elcim Y, Adanali A, Sanlidilek U, Akyar S. Comparison of effective doses obtained from dose-area product and air kerma measurements in interventional radiology. Br J Radiol. 2004;77:315–322.
11. Jolly SS, Yusuf S, Cairns J, Niemelä K, Xavier D, Widimsky P, Budaj A, Niemelä M, Valentin V, Lewis BS, Avezum A, Steg PG, Rao SV, Gao P, Afzal R, Joyner CD, Chrolavicius S, Mehta SR; RIVAL Trial Group. Radial versus femoral access for coronary angiography and intervention in patients with acute coronary syndromes (RIVAL): a randomised, parallel group, multicentre trial. Lancet. 2011;377:1409–1420.
12. Kuipers G, Velders XL, Piek JJ. Exposure of cardiologists from interventional procedures. Radiat Prot Dosimetry. 2010;140:259–265.
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Chapter 2
Clinical and procedural characteristics associated
with higher radiation exposure during percutaneous
coronary interventions and coronary angiography
Ronak Delewi, Loes P. Hoebers, Truls Råmunddal, José P.S. Henriques, Oskar Angerås, Jason Stewart, Lotta Robertsson, Magnus Wahlin, Petur Petursson, Jan J. Piek, Per Albertsson, Göran Matejka, Elmir Omerovic
ABSTRACT
Background We aim to study the clinical and procedural characteristics associated with
higher radiation exposure in patients undergoing percutaneous coronary interventions (PCIs) and coronary angiography.
Methods and Results Our present study included all coronary angiography and PCI
procedures in 5 PCI centers in the Western part of Sweden, between January 1, 2008, and January 19, 2012. The radiation exposure and clinical data were collected prospectively in these 5 PCI centers in Sweden as part of the Swedish Coronary Angiography and Angioplasty Registry (SCAAR). A prediction model was made for the radiation exposure (dose–area product) expressed in Gy ∙cm2. A total of 20 669 procedures were included in the present study, consisting of 9850 PCI and 10 819 coronary angiography procedures. In multivariable analyses, body mass index (β=1.04; confidence interval [CI], 1.04–1.04; P<0.001); history of coronary artery bypass graft surgery (β=1.32; CI, 1.28–1.32; P<0.001); 2, 3, or 4 treated lesions (2 treated lesions: β=1.95; CI, 1.84–2.03; P<0.001; 3 treated lesions: β=2.34; CI, 2.16–2.53; P<0.001; and 4 treated lesions: β=2.83; CI, 2.53–3.16; P<0.001); and chronic total occlusion lesions (β=1.39; CI, 1.31– 1.48; P<0.001) were associated with the highest radiation exposure. After adjusting for procedural complexity, radial access route was not associated with increased radiation exposure (β=1.00; CI, 0.98–1.03; P=0.67).
Conclusions In the largest study population to assess radiation exposure, we found that
high body mass index, history of coronary artery bypass graft surgery, number of treated lesions, and chronic total occlusions were associated with the highest patient radiation exposure. Radial access site was not associated with higher radiation exposure when compared with femoral approach.
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INTRODUCTION
Radiation dose reduction for percutaneous coronary intervention (PCI) is particularly important as procedures become more complex. This could potentially result in longer procedures and expose patients to an increased or a higher procedural related radiation. The International Commission on Radiological Protection1 has described the risks of radiation exposure from fluoroscopy-guided procedures. They reported an increase of radiation-induced injuries in patients’ skin (deterministic effect) and an increase of the risk to develop radiation-induced cancers (stochastic effect).
Therefore, it is of utmost importance to study the factors that are associated with increased radiation exposure during coronary diagnostic and interventional procedures. In addition, in the recent years, these coronary procedures have been increasingly performed using the radial access for several reasons.
However, contradictory results are reported on the radiation exposure of patients from procedures performed by the radial route.2–7 In the present study, we studied the radiation exposure data of a large real-world patient population undergoing routine coronary angiography (CAG) or PCI. The aims of the study are 2-fold. First, to assess the clinical, angiographic, and procedural characteristics that are associated with increased radiation exposure. Second, to assess whether the radial access route, compared with femoral access route, is associated with increased radiation exposure during CAG and PCI.
METHODS
Setting
Our study included CAG and PCI procedures in 5 PCI centers in the Western part of Sweden, Västra Götaland, between January 1, 2008, and January 19, 2012. The 5 PCI centers included in this analysis were (1) Sahlgrenska University Hospital, Gothenburg; (2) Östra Hospital, Gothenburg; (3) Norra Älvborgs Hospital, Trollhättan; (4) Södra Älvsborg Hospital, Borås; and (5) Skaraborg Hospital Skövde, Skövde.
The data about the patient’s characteristics and procedural details for the 5 PCI centers were obtained from the Swedish Coronary Angiography and Angioplasty Registry (SCAAR). Briefly, this registry holds data on consecutive patients from all 30 centers that perform CAG and PCI in Sweden. The registry is sponsored by the Swedish Health Authorities and is independent of commercial funding. The registry was approved by an institutional review committee in Gothenburg. All consecutive patients undergoing CAG or PCI are included. A diagnostic CAG procedure is described by ≈50 variables, whereas a PCI procedure is described with ≈200 variables. The information about clinical and procedural characteristics is entered into the registry immediately after the procedure by the PCI physician after the review of clinical information. Since 2001, the registry has a Web-based case report platform with automatic data surveillance.8 At each hospital, a dedicated person is appointed to verify whether all the procedures performed are entered into the registry. Patient variables included clinical (ie, age, risk factors, sex, and cardiac history), angiographic, and procedural characteristics (ie, number of stent implantation and type of lesion).
More than 4500 PCIs and CAGs are performed at the 5 PCI centers each year, from 4574 in 2004 to 6153 procedures in 2011. The centers are teaching institutions, and procedures are routinely performed by a staff interventional cardiologist alone or together with an interventional fellow-in-training. There were 23 interventional cardiologists working within the units during the entire observation period, with experience in both the radial and femoral approaches. For this analysis, we only included procedures performed by a licensed interventional cardiologist, performing ≥100 CAGs via the radial route during the study period.
Data Assembly
Patients on whom PCI was performed have been classified as such. This rule also applied to patients who went for CAG with the option of PCI in the same procedure. All procedural decisions, including device selection and adjunctive pharmacotherapy, were made at the discretion of the operator. A bifurcated lesion was defined as ≥50% narrowing of the vessel diameter involving both the main and side branches, based on
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visual assessment on the angiogram as assessed by the operator. Chronic total occlusion (CTO) was defined as 100% luminal diameter stenosis and the absence of antegrade flow known or assumed to be ≥12 weeks of duration. In this analysis, access routes were classified according to the first access site, so if first access site was radial but conversion to the femoral route occurred, it was classified as radial based on an intention-to-treat principle. Procedures in which first access site was simultaneously femoral and radial were classified as such in both analyses.
Radiation Measurements and Radiation Protection
The radiation exposure of patients undergoing CAG and PCI was measured using dose– area product (DAP) meters. The DAP is the product of the dose value of the incident radiation and the irradiated field size and is expressed in Gy·cm2. The DAP meters were integrated in the x-ray systems. The x-ray systems provided direct feedback of the radiation exposure on the monitor of the x-ray systems. The radiation exposure from fluoroscopy mode and cine mode, as well as the total radiation exposure (fluoroscope mode and cine mode), was displayed on the monitor of the x-ray systems. Moreover, the fluoroscopy time (in minutes) was displayed on the monitor. The DAP values and the fluoroscopy time were entered into the SCAAR registry.
The procedures were performed in 5 different hospitals, which included 6 catheterization laboratories in total. Four catheterization rooms are equipped with Philips X-ray systems (Philips Medical Systems, Best, The Netherlands), 3 Integris H5000 systems, and an Allura system.
Two catheterization rooms were equipped with Siemens X-ray systems (Siemens, Erlangen, Germany) an Coroscope, and an Axiom Artis. Field of views were of 25, 19, and 15 cm diagonal square. In the cine mode, the number of frames was variable: either 12.5 or 25 frames/s. The interventional cardiologists used lead aprons and thyroid collars of 0.50-mm lead equivalent thickness at 100 kVp. Furthermore, the interventional cardiologists used ceiling-mounted lead glass screens (Pb equivalent, 0.50 mm) and table shield systems (Pb equivalent, 0.50 mm).
STATISTICAl ANAlySES
Continuous variables were expressed as mean and SD, and categorical variables were expressed as count and percentage. We made a prediction model for the natural logarithm of the radiation exposure because the distributions of the DAP values were positively skewed. Predictors of radiation exposure were investigated using multivariable linear regression. The primary observational unit was a procedure. Baseline variables that were significant at P≤0.10 on univariable analysis or variables that were known to be associated with radiation exposure were forced into the model. The database was scrutinized for missing data. Logistic regression showed that several variables predicted a (P<0.05) probability of having missing data, including dyslipidemia (3.0% missing), diabetes mellitus (0.8% missing), history of coronary artery bypass graft surgery (CABG; 0.3% missing), and body mass index (BMI; 10.7% missing). Stata (version 12.1) module for multiple imputation was used to estimate missing data and regression modeling. In addition to the complete case analysis, we applied multiple imputation methods to estimate missing data. The imputation protocol consisted of the chain equation method9 using the same covariates as in the main model with 20 imputed data sets. The imputation procedure and subsequent multivariable regression models were performed according to the Rubin’s protocol under the assumption that missing data are missing at random. In the second analysis, we compared the geometric radiation exposure between femoral access and radial access procedures. We adjusted for differences in clinical and procedural characteristics by means of multivariable regression model. Because of the hierarchical structure of our database with the individuals clustered within PCI operators and the operators clustered within hospitals, we have also analyzed the data using multilevel multivariable linear regression to adjust for clustering effect (primary analysis). This is because of the fact that the observations (procedures) performed on the same patient, procedures performed by the same operator, and procedures performed at the same catheterization laboratory are not independent of each other. This causes violation of the assumption of independency.
Multilevel modeling adjusts for the correlation between clustered observations by introducing random-effect in the model.10 Baseline variables that were significant at P≤0.10 on univariable analysis or variables that were known to be associated with radiation exposure were entered into the model. Then, radial access site was forced into the model. In this analysis, patients were excluded in case of preference for the femoral approach, including (1) patients who had a history of CABG, (2) patients with CTO, and (3) patients who were presented with cardiogenic shock or procedures in which intraortic balloon pump or other assist devices were used. All analyses were performed with SPSS (version 19.0; Chicago, IL) and Stata (version 12.1 StataCorp, College Station, TX) software. Statistical significance was considered at P<0.05.
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RESUlTS
Patients
The total number of procedures included in the present study is 20 669, consisting of 10 819 CAGs and 9850 PCIs. In total, 25 291 CAG and PCI procedures were performed during the study period. We excluded procedures not performed by a licensed interventional cardiologist performing ≥100 CAG via the radial route in the study period (n=4057).
Mean log-transformed DAP in our study population was 3.91±0.84 (Figure). Radiation exposure data were not available for 565 patients. Clinical and angiographic characteristics of patients with missing radiation exposure data were similar to the study population (data not shown). In Table 1, patient and procedure characteristics of the entire study population are shown. The study population consisted of 68% men, 18% patients with diabetes mellitus, and 11% patients with a history of CABG. In 59% of the procedures, access route was radial, and 4.0% of all radial procedures were converted to the femoral access site (n=495).
The results of the multilevel regression analysis for radiation exposure are shown in Table 2. Multivariable predictors of increased radiation exposure were age, male sex, high BMI, diabetes mellitus, dyslipidemia, history of CABG, number of diseased vessels, number of lesions treated, and complex lesion type (type B1, B2, C, bifurcation lesions, and CTO). Also, thrombus aspiration and the use of intraortic balloon pump or
Table 1 Patient and procedural characteristics of the study population
Baseline characteristic N = 20 669
Age (years) 65.9 ± 11.6
Male gender 68% (14,056)
Body mass index (kg/m2) 27.3 ± 5.1
Diabetes mellitus 18% (3,719)
Current cigarette smoking 15% (3,137)
Hypertension 52% (10,835)
Dyslipidemia 53% (10,879)
History of PCI 23% (4,792)
History of CABG 11% (2,268)
Date of CAG or PCI
Jan. 2008 – Dec.2008 27% (5,471)
Jan. 2009 – Dec.2009 24% (4,869)
Jan. 2010 – Dec. 2010 24% (4,955)
Jan. 2011 – Jan. 2012 26% (5,374)
Indication for CAG
STEMI 16% (3,194)
Unstable angina/NSTEMI 37% (7,727)
Stable CAD or other 47% (9,748)
Access site
Femoral 38% (7,822)
Radial 59% (12,153)
Both femoral and radial 0.7% (151)
Radial converted to femoral 2% (495)
Femoral converted to radial 0.1% (22)
Axillary or brachial 0.1% (23) Vessel disease 0 30% (6,138) 1 28% (5,779) 2 19% (3,817) 3 16% (3,339) LM 7% (1,528)
No. of lesions treated per PCI
0 52% (10,819)
1 27% (5,567)
2 13% (2,748)
3 5% (1,011)
≥4 3% (524)
Treated Lesion treated per PCI
LM 2% (418) LAD 23% (4753) RCX 12% (2427) RCA4 16% (3398) Lesion type A 8% (1,640) B1 20% (4,135) B2 17% (3,597) C 11% (2,226) Bifurcation lesion 1 2% (443) ≥2 1% (221)
Chronic total occlusion 2% (439)
Thrombus aspiration 5% (952)
Cardiogenic shock 1% (225)
Use of aorta balloon pump or other assist devices 2% (307)
CABG: coronary artery bypass surgery, CAD: coronary artery disease, CAG; coronair angiogram, LAD; left anterior descending artery, LM: left main artery, NSTEMI; non-ST elevation myocardial infarction, PCI; percutaneous coronary interventions, RCA; right coronary artery, RCX; left circumflex artery, STEMI: ST elevation myocardial infarction
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Table 2 Multivariable analysis of predictors of radiation exposure (LnDAP) in the entire studypopulation (complete case analysis)
N= 20,669 B Confidence Interval P-value
Intercept 5.69 5.26 to 6.17 <0.001
Age (per 11.6 years) 1.07 1.06 to 1.08 <0.001
Male gender 1.45 1.42 to 1.48 <0.001
Body mass index (per 5.1 kg/m2) 1.25 1.24 to 1.26 <0.001
Diabetes mellitus 1.06 1.03 to 1.08 <0.001
Dyslipidemia 1.02 1.01 to 1.04 0.013
History of CABG 1.32 1.28 to 1.35 <0.001
Date of CAG or PCI
Jan. 2009 – Dec.2009 0.92 0.34 to 0.94 <0.001 Jan. 2010 – Dec. 2010 0.87 0.84 to 0.89 <0.001 Jan. 2011 – Jan. 2012 0.78 0.76 to 0.80 <0.001 Access site Radial 1.01 0.99 to 1.03 0.17 Femoral 0.97 0.90 to 1.05 0.36 Axillary or brachial 1.34 1.03 to 1.72 0.03 Vessel disease 0 0.83 0.80 to 0.85 <0.001 1 1.15 1.13 to 1.19 <0.001 2 1.26 1.22 to 1.30 <0.001 3 1.30 1.26 to 1.34 <0.001
No. of lesions treated per PCI
0 0.93 0.87 to 0.99 <0.001 1 1.62 1.57 to 1.68 <0.001 2 1.95 1.84 to 2.03 <0.001 3 2.34 2.16 to 2.53 <0.001 ≥4* 2.83 2.53 to 3.16 <0.001 Treated Lesion Lesion type A 0.94 0.90 to 0.98 0.008 B1 1.03 1.00 to 1.06 <0.001 B2 1.05 1.02 to 1.08 <0.001 C 1.11 1.07 to 1.14 <0.001 CTO lesion 1.39 1.31 to 1.48 <0.001 Bifurcation lesion 1.14 1.06 to 1.21 <0.001 Thrombus aspiration 1.11 1.06 to 1.16 <0.001 Hospital 1 1.02 0.95 to 1.09 0.27 2 0.65 0.62 to 0.69 <0.001 3 1.01 0.71 to 1.31 0.59 4 0.81 0.76 to 0.86 <0.001 5 0.73 0.46 to 1.15 0.18 Operators (1-23) 0.64-1.62 0.63 to 1.67 <0.001
*confidence interval not symmetrical due to rounding issues
B: estimated regression coefficient CABG: coronary artery bypass surgery, CAD: coronary artery disease, CAG; coronair angiogram, CTO; chronic total occlusion, LAD; left anterior descending artery, LM: left main artery, NSTEMI; non-ST elevation myocardial infarction, PCI; percutaneous Coronary Interventions, RCA; right coronary artery, RCX; left circumflex artery, STEMI: ST elevation myocardial infarction
other assist devices were associated with increased radiation exposure. Moreover, there was a wide range of radiation exposure associated with each interventional cardiologist. Among these predictors, BMI (per 5.1 g/m2; β=1.25; confidence interval [CI], 1.24– 1.26; P<0.001); history of CABG (β=1.32; CI, 1.28–1.32; P<0.001); 2, 3, or 4 treated lesions (2 treated lesions: β=1.95; CI, 1.84–2.03; P<0.001; 3 treated lesions; β=2.34; CI, 2.16–2.53; P<0.001; and 4 treated lesions: β=2.83; CI, 2.53–3.16; P<0.001); and chronic total lesions (β=1.39; CI, 1.31–1.48; P<0.001) were associated with the highest radiation exposure. During the study period, radiation exposure decreased with time. After imputation of missing values, the multivariable predictors of radiation exposure did not differ.
In a second analysis, we assessed whether the radial access route is associated with increased radiation exposure. In this analysis, patients with a history of CABG (n=2268), a CTO (n=439), or >2 bifurcated lesions (n=221) and patients who were presented with cardiogenic shock (n=225) or procedures in which intraortic balloon pump or other assist devices were used (n=307) were excluded from the analysis. Two hundred fifty-six procedures had ≥2 of these characteristics, 32 procedures had 3 characteristics, and 2 procedures had 4 exclusion criteria, making a total of 17 535 procedures. Of these 17 535 procedures, 17 procedures were treated using the axillary or brachial access route, 103 with simultaneously femoral and radial access site, and access site of 3 procedures was missing. These procedures were excluded, making a total of 17 412 procedures included in the second analysis.
Median DAP value was 48 (interquartile range [IQR], 28–85) Gy·cm2 for procedures performed via femoral route (n=5742) compared with 44 (26–75) Gy·cm2 for procedures performed via radial route (n=11 670; P<0.001). Median radiation exposures of the patients undergoing a PCI via the femoral route (n=2792) was 79 (51–122) Gy·cm2 compared with 73 (48–112) Gy·cm2 for procedures performed via radial route (n=5056;
P<0.001). The median exposure for CAGs was 31 (21–47) Gy·cm2 and 31 (20–46) Gy·cm2 for procedures performed via femoral route (n=2950) and procedures performed via radial route (n=6614; P=0.18), respectively. After multivariable analysis, radial access route remained not associated with increased radiation exposure (β=0.004; SE=0.001;
P=0.67). Also after imputing missing values, in multilevel analysis, radial access route
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Table 3 Multiple analyses of predictors of radiation exposure (LnDAP) to assess whether radialaccess site (compared to other access site) is associated with increased radiation exposure
B Confidence Interval P-value
Complete case multivariable linear regression 1.00 0.98 to 1.03 0.67
Imputed multivariable linear regression* 1.01 0.99 to 1.05 0.27
Complete case multilevel linear regression 1.00 0.98 to 1.03 0.49
Imputed multilevel linear regression* 1.01 0.99 to 1.05 0.24
B: estimated regression coefficient, *confidence interval not symmetrical due to rounding issues
DISCUSSION
In the largest study population to assess radiation exposure in CAG and PCI, we found that high BMI, history of CABG, number of treated lesions, and CTOs were associated with the highest patient radiation exposure. Radial access site was not associated with higher radiation exposure.
A previous study of 1287 male and 540 female patients undergoing PCI also found that lesion complexity, PCI of left circumflex artery, and number of lesions treated were correlated with increased radiation exposure.11 Other factors that were associated with increased radiation exposure were body mass index, previous CABG, and peripheral vascular disease. However, in that study, exposure in air values (R, type 1) and the air kerma values (Gy, type 2) were measured and were converted to cumulative skin dose. However, estimations of effective doses12 of patients using DAP measurements may be more accurate than using air kerma measurements because DAP allows for variations in field size.13
In this study, we found that high BMI, history of CABG, CTO lesions, and 2, 3, or 4 treated lesions were associated with the highest radiation exposure. Although these factors cannot be directly influenced before conducting the CAG or PCI, it is important to know these factors so that patients can be adequately informed. Also, when treating complex or CTO lesions, especially in patients with high BMI or previous CABG, radiation management can be incorporated into preprocedure planning as well as in defining maximum levels that could guide physicians in decision making during the procedure accordingly. Finally, we and Fetterly et al11 have demonstrated that individual PCI operators have a substantial influence on patient dose. Therefore, all staff and trainee physicians should be well trained in behavioral and technical methods to minimize radiation dose.
Several reports have compared the radiation exposure of patients from procedures performed by the radial route with procedures performed by the femoral route with contradictory results. Sandborg et al2 reported higher exposure of patients from procedures performed by the radial route for both PCIs and CAGs. In their study, the interventional cardiologists were experienced in performing the procedures by the femoral route, whereas the radial route was used as a complementary technique to the femoral route. Lange and von Boetticher3 also reported higher exposure of patients for CAG procedures assessed by the radial route, whereas for PCI procedures, the exposure did not differ between both access routes. The higher exposure for CAGs performed by the radial route was explained by a higher fluoroscopy time because of difficulties in advancing the catheter across the aortic arch. Finally, 2 other studies also reported higher exposure of patients from procedures performed by the radial route.4,5 However, in 1 study, the mean body weight of the group of patients treated by the femoral route was lower compared with the mean body weight of the group of patients who underwent the procedures by the radial route.4 In the other study, the air kerma (in Gy) was used as a measure for radiation exposure.5 The findings from the present study were comparable with the findings reported by Geijer and Persliden6 and Kuipers et al.7 In these studies, radial access site was not associated with increased radiation exposure.
The RadIal Vs femorAL access for coronary intervention (RIVAL) study was a large, randomized trial comparing radial and femoral access for CAG and intervention.14 Duration of fluoroscopy was higher in the radial access group (9.3 [5.8–15] minutes) compared with that in the femoral access group (8.0 [4.5–13] minutes). However, the authors did not directly measure radiation exposure. Moreover, the average annual operator’s volume was relatively low.
Our analysis has several limitations. The radiation dose received by a patient during an interventional procedure is highly variable and is also dependent on many technical factors. This is partly reflected by a substantial variability in radiation exposure observed among the interventional cardiologists in our study population. The technical factors affecting radiation dose are x-ray imaging type and fluoroscopic and acquisition imaging dose rate settings. Unfortunately, in this analysis, we did not take these factors into account. It is likely that the mode of operation contributed to the variation in exposure of the patients. It is also possible that differences in distance to the patients during exposures contributed to the variation in patients’ exposure, for instance, the position of the x-ray tube, the height of the table, and the distance between patient and image intensifier during the procedures. We did not measure these variables and were, therefore, unable to include them in the statistical models. However, we did apply multilevel modeling, which is a recommended statistical approach in the case of clustering of observations.3 Moreover, the radiation exposure of the interventional cardiologists was not measured.
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During interventional procedures performed by the radial route, the interventional cardiologists are usually closer to patients than during procedures performed by the femoral route. Because the intensity of scattered radiation close to patients is higher than the intensity at greater distances, it is possible that the radiation exposure of interventional cardiologists from procedures performed by the radial route is higher compared with exposure from procedures performed by the femoral route. However, in a previous study,15 a linear relation was found between the exposure of 4 weekly measurements measured outside the lead aprons of the interventional cardiologists and the exposure of patients, irrespective of the interventional cardiologists or number of performed radial/femoral procedures.
In conclusion, we found that high BMI, history of CABG, number of treated lesions, and CTOs were associated with the highest patient radiation exposure. Radial access site was not associated with higher radiation exposure when compared with femoral approach.
