Comparative Analysis of Radial Versus Femoral Diagnostic Cardiac Catheterization Procedures in a Cardiology Training Program

Abstract: Objectives. This study was conducted to evaluate the differences in the procedural variables between transradial and transfemoral access for coronary angiography, with cardiology fellows as the primary operators. Methods. This was a retrospective study of 163 radial and 180 femoral access diagnostic cardiac catheterization procedures, and involved cardiology fellowship trainees as primary operators. Results. The radial approach was associated with significantly higher fluoroscopy time (8.0 ± 6.97 min vs 4.25 ± 3.01 min; P<.001), dose area product (10775 ± 6724 µGy/m² vs 7952 ± 4236 µGy/m²; P<.001), procedure time (38.31 ± 12.25 min vs 27 ± 17.56 min; P<.001), procedure start to vascular access time (8.24 ± 6.31 min vs 5.31 ± 4.59 min; P<.001), and vascular access to procedure end time (30 ± 15.34 min vs 21.2 ± 9.57 min; P<.001). These differences persisted after adjusting for patients with bypass grafts and additional imaging (P<.001). The contrast amount was not significantly different between the two groups (P=.12). Procedure start to vascular access time improved significantly with fellowship training year in both the radial (9.57 ± 6.96 min vs 8.23 ± 6.08 min vs 5.57 ± 4.82 min) and femoral groups (6.17 ± 5.07 min vs 5.47 ± 4.75 min vs 4.01 ± 3.31 min). Fluoroscopy time showed significant difference in only the femoral access group (P=.01). Dose area product did not improve with training in either access group. Conclusion. Radial procedures were associated with higher radiation dose and longer procedure time. Despite decrease in total procedural time for radial cases with the level of training, total radiation dose did not decrease. 

J INVASIVE CARDIOL 2016;28(6):254-257. Epub 2016 May 15.

Key words: fellowship training, cardiac catheterization, transfemoral, transradial

Transradial coronary angiography was first reported by Campeau in 1989.¹ Although initially used as a backup to transfemoral access, the use of transradial access as a primary access site has gained worldwide momentum over the last two decades and is being used increasingly for diagnostic as well as interventional coronary procedures.^2,3 Some European countries have reported high use of radial access of up to 71% for coronary angiography.⁴ Benefits related to transradial percutaneous coronary intervention include reduced bleeding risk, reduced length of stay and costs, early ambulation, and improved patient comfort and possible same-day discharge. Disadvantages of the transradial technique include a steep learning curve, limitations in the guide-catheter size and that transradial approach is not routinely taught in fellowship programs.^5,6 The current published data comparing transradial with transfemoral access for coronary angiography and angioplasty are largely based on studies, analyzing procedures performed by experienced operators. Data comparing procedural variables between transradial and transfemoral approach at the level of general cardiology fellows are scarce. Our study compares the procedural efficiency and radiation exposures between radial and femoral access techniques in diagnostic coronary angiograms performed by cardiology fellowship trainees as primary operators.

Methods

Study design, data source, and patients. This study was organized at a major metropolitan city in the United States. Rush University Medical Center in Chicago, Illinois supports a cardiology fellowship training program comprised of six general cardiology fellows admitted annually. Cardiology fellows at this center rotate at cardiac catheterization laboratories in Rush University Medical Center, Rush Oak Park Hospital, and John H. Stroger Jr. Hospital of Cook County; within these facilities, fellowship trainees are regularly exposed to both transradial and transfemoral procedures. For a large majority of cases, a general cardiology fellow is designated as the primary operator for the diagnostic cardiac catheterization case he or she participates in while the supervising interventional cardiology attending is designated as the secondary operator. If the primary operator fails to obtain arterial access after 2 or 3 attempts, the secondary operator obtains access. Similarly, if the primary operator fails to engage the coronary arteries or bypass grafts after a few attempts, the secondary operator continues the procedure. 

The data for this study are derived only from the cardiac catheterization laboratory of Rush University Medical Center. We conducted a retrospective cohort study of 343 diagnostic cardiac catheterization procedures (180 femoral, 163 radial) from January 2012 to September 2014 performed by cardiology fellowship trainees. Inclusion criteria for our study required a general cardiology fellow (PGY-4, PGY-5, or PGY-6) to be the primary operator for a diagnostic cardiac catheterization procedure. Exclusion criteria consisted of incomplete data for analyzing data points, and any additional procedures such as right heart catheterization, percutaneous coronary interventions, and peripheral vascular angiogram. The choices of access site and sheath size were made at the discretion of the operator. Patients were included in groups based on the first attempted access site. This study was approved by the Rush Institutional Review Board and was deemed not to require informed consent.

Variables and definitions. Recorded variables included level (year) of training, total procedure time (time duration between administration of local anesthetic and procedure end), procedure start to vascular access time (time duration between administration of local anesthetic and insertion of sheath), fluoroscopy time, dose area product (measured in µGy/m²), number of catheters used, milliliters of contrast volume used, need for change of access site, comorbid conditions, and reported complications. Any additional procedures (such as left ventriculography, aortography, and coronary artery bypass graft angiography) performed were recorded.

Statistical analysis. The R statistical program was used to perform data analysis. For demographics, Pearson Chi-square test was used for the dichotomous variables, and Student’s t-test for the continuous variables (except for body mass index, because that distribution did not fulfill the assumptions of the Student’s t-test). Mann-Whitney test was used to compare the two access groups, and rank analysis of variance was used to compare the three groups of fellows. Both tests dealt with ordinal continuous variables.

Results

Baseline characteristics. Out of 343 diagnostic coronary angiograms studied, a total of 163 cases were performed via transradial access. Baseline characteristics including age, sex, diabetes mellitus, hypertension, history of smoking, body mass index, dyslipidemia, and history of prior coronary artery bypass graft surgery are shown in Table 1. Hypertension and dyslipidemia were significantly lower in the radial group. The number of patients with coronary artery bypass grafts was strikingly greater in the femoral groups (13.9% vs 3.6%; P=.01). Body mass index and number of smokers were higher in the radial group, but the differences were statistically insignificant.

Procedural variables. The radial approach was associated with significantly higher fluoroscopy time (8.0 ± 6.97 min vs 4.25 ± 3.01 min; P<.001), dose area product (10775 ± 6724 µGy/m² vs 7952 ± 4236 µGy/m²; P<.001), procedure time (38.31 ± 12.25 min vs 27 ± 17.56 min; P<.001), procedure start to vascular access time (8.24 ± 6.31 min vs 5.31 ± 4.59 min; P<.001), and vascular access to procedure end time (30 ± 15.34 min vs 21.2 ± 9.57 min; P<.001). Contrast amount was not significantly different between the two groups (Table 2). 

Statistical analysis was repeated after adjusting for additional procedures including coronary artery bypass angiography, left ventriculography, and aortography. These results showed that radial procedures were associated with significantly higher fluoroscopy time (7.44 ± 5.86 min vs 3.51 ± 1.9 min; P<.001), dose area product (10,411 ± 6465 µGy/m² vs 7009 ± 3322 µGy/m²; P<.001), procedure time (35.78 ± 13.85 min vs 25.01 ± 9.95 min; P<.001), procedure start to vascular access time (7.84 ± 6.14 min vs 5.12 ± 4.17 min; P<.001), and vascular access to procedure end time (27.62 ± 12.28 min vs 19.32 ± 7.11 min; P<.001). Contrast amount was not significantly different between the two groups after adjustment (Table 3). 

Changes in procedural variables were compared through successive years of fellowship training. Total procedure time improved significantly in the radial group from 41.67 ± 21.47 min among first year trainees, to 38.01 ± 14.55 min among second year trainees and 32.18 ± 14.35 min among third year trainees (P=.01) (Figure 1). Procedure start to vascular access time improved significantly with successive levels of fellowship training (Figure 2) in both the radial (9.57 ± 6.96 min vs 8.23 ± 6.08 min vs 5.57 ± 4.82 min in the first, second, and third years, respectively) and femoral groups (6.17 ± 5.07 min vs 5.47 ± 4.75 min vs 4.01 ± 3.31 min in the first, second, and third years, respectively). Vascular access to procedure end time improved significantly only in the femoral group (24.15 ± 11.54 min vs 20.53 ± 8.68 min vs 18.99 ± 7.72 min in the first, second, and third years, respectively) (Figure 3). Fluoroscopy time showed significant change only in the femoral access group (P=.01). Dose area product did not improve with training in either access group.

Discussion

Cardiology fellowship trainees contribute toward patient care in academic medical centers in a major way. This includes performance of invasive procedures in the cardiac catheterization laboratory. Major studies that have compared radial versus femoral access techniques have focused on data obtained from skilled, experienced operators; similar data with cardiology fellows as primary operators are limited. The RIVAL trial⁶ randomized patients with acute coronary syndrome to radial and femoral access groups and investigated the efficacy and bleeding outcomes between the two vascular access techniques. Radial artery access reduced the primary outcome (death, myocardial infarction, stroke, non-coronary artery bypass graft related major bleeding) in patients with ST-elevation myocardial infarction; however, this benefit was not observed in patients with non-ST elevation myocardial infarction. In this trial, mean fluoroscopy time in cases of ST-elevation myocardial infarction was 9.3 min (range, 6.0-15.0 min) using transradial access compared with 8.0 min (range, 5.0-13.0 min) using transfemoral access. Volume of contrast used (180 mL) was unchanged between the two groups. The above-stated numbers are from experienced operators and we do not know the degree of fellowship trainee involvement.

The fellowship training period is a unique time to compare procedural variables, as both access techniques are new to fellowship trainees. This could reduce inherent bias that may be present with more experienced operators who may have developed a personal preference in using one access technique over the other. This retrospective study was designed to compare procedural variables between these two approaches, because this has bearing on cardiology fellowship training and is representative of the clinical care that is provided at academic medical centers. Major findings from our study include the following: (1) When fellows are primary operators, transradial procedures were associated with significantly higher radiation doses and procedural times; (2) Time to gain vascular access improved with level of fellow training; (3) Vascular access to procedure end time showed a significant decrease in the femoral group only; and (4) Despite significant improvement in total procedural time in transradial cases with increased training, radiation dose did not decrease. 

Our findings that transradial procedures take longer total time and are associated with higher radiation dose is consistent with the finding of Brueck et al and Balwanz et al.^7,8 Michael et al reported similar findings while studying radial access for coronary artery bypass graft patients.⁹ The above-stated differences persisted even after adjusting for additional procedures. This is likely due to the increased technical difficulty of cannulating coronary arteries and bypass grafts due to anatomical and equipment-related factors.

Vascular access time showed improvement in both transradial and transfemoral groups. This could have contributed to improvement in total procedure time in the transradial group, despite the transradial group showing no significant improvement in vascular access to procedure end time. 

Higher radiation dose associated with radial diagnostic coronary angiograms has been shown for experienced operators.¹⁰ This goes along with no significant change in radiation dose with training as measured by dose area product in our study. With increasing level of training, although most of the procedural parameters showed improvement, not all reached statistical significance.

Study limitations. This work is constrained by the limitations inherent in a retrospective study. Our sample is from a single center and limited to a relatively short time frame. In addition, variables such as patient satisfaction and comfort were not included due to design of this study. Clinical variables like complications rates were not included in this analysis due to a very small complication rate in both groups. This finding could have been a result of the suitable selection of patients by attending physicians for fellowship trainees to gain vascular access. Despite these limitations, our study has potential implications in guiding fellowship training curriculum by demonstrating that transradial access poses a steeper learning curve for cardiology fellows compared with the transfemoral approach. 

Conclusion

This study is unique because it provides a real-world comparison of procedural variables in a training program. It shows that radiation exposure levels and procedure times are higher in the transradial group. Training fellows in transradial coronary angiograms improved procedure time but did not translate into a decrease in dose area product.

References

1.    Campeau L. Percutaneous radial artery approach for coronary angiography. Cathet Cardiovasc Diagn. 1989;16:3-7.

2.    Feldman DN, Swaminathan RV, Kaltenbach LA, et al. Adoption of radial access and comparison of outcomes to femoral access in percutaneous coronary intervention: an updated report from the national cardiovascular data registry (2007-2012). Circulation. 2013;127:2295-2306.

3.    Bertrand OF, Rao SV, Pancholy S, et al. Transradial approach for coronary angiography and interventions: results of the first international transradial practice survey. JACC Cardiovasc Interv. 2010;3:1022-1031. 

4.    García del Blanco B, Hernández Hernández F, Rumoroso Cuevas JR, Trillo Nouche R. Spanish cardiac catheterization and coronary intervention registry. 23rd official report of the Spanish Society of Cardiology Working Group on Cardiac Catheterization and Interventional Cardiology (1990-2013). Rev Esp Cardiol (Engl Ed). 2014;67:1013-1023.

5.    Jolly SS, Amlani S, Hamon M, Yusuf S, Mehta SR. Radial versus femoral access for coronary angiography or intervention and the impact on major bleeding and ischemic events: a systematic review and meta-analysis of randomized trials. Am Heart J. 2009;157:132-140. 

6.    Mehta S, Jolly S, Cairns J, et al. Effect of radial versus femoral artery access in patients with coronary syndromes with or without ST-segment elevation. J Am Coll Cardiol. 2014;63:954-963. Epub 2013 Nov 21.

7.    Cooper CJ, El-Shiekh RA, Cohen DJ, et al. Effect of transradial access on quality of life and cost of cardiac catheterization: a randomized comparison. Am Heart J. 1999;138:430-436.

8.    Brueck M, Bandorski D, Kramer W, Wieczorek M, Höltgen R, Tillmanns H. A randomized comparison of transradial versus transfemoral approach for coronary angiography and angioplasty. JACC Cardiovasc Interv. 2009;2:1047-1054. 

9.    Balwanz CR, Javed U, Singh GD, et al. Transradial and transfemoral coronary angiography and interventions: 1-year outcomes after initiating the transradial approach in a cardiology training program. Am Heart J. 2013;165:310-316.

10.    Michael TT, Alomar M, Papayannis A, et al. A randomized comparison of the transradial and transfemoral approaches for coronary artery bypass graft angiography and intervention: the RADIAL-CABG Trial (RADIAL Versus Femoral Access for Coronary Artery Bypass Graft Angiography and Intervention). JACC Cardiovasc Interv. 2013;6:1138-1144. 

11.    Shah B, Bangalore S, Feit F, et al. Radiation exposure during coronary angiography via transradial or transfemoral approaches when performed by experienced operators. Am Heart J. 2013;165:286-292.

From the Division of Cardiology, Rush University Medical Center Chicago, Illinois.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted March 21, 2016, provisional acceptance given March 24, 2016, final version accepted April 1, 2016.

Address for correspondence: Neeraj Jolly, MD, 1717 W. Congress Parkway, 317 Kellogg, Chicago, IL 60612. Email: neeraj_jolly@rush.edu