Safety and Efficacy of Transradial Access in Coronary Angiography: 8-Year Experience

Abstract: Aims. The transradial approach (TRA) in coronary angiography is used less frequently than the transfemoral approach; the learning curve and transradial failure (TRF) have slowed its widespread use. We evaluate the incidence, causes, and predictors of TRF in TRA coronary angiographies in an unselected population. Methods and Results. All elective coronary angiographies using TRA from January 2002 to December 2009 were analyzed in this single-center, prospective, observational study. TRF occurred in 465/8463 procedures (5.5%). The main causes of TRF were puncture failure in 48.3% and tortuous brachiocephalic arteries in 22.8% of cases. The annual TRF percentage decreased from 9.1% in 2002 to 4.1% in 2009 (P<.001). In a multivariable regression model, the independent factors associated with TRF included use of >3 catheters (odds ratio [OR], 3.973; confidence interval [CI], 3.198-4.937), abnormal Allen test (OR, 3.231; CI, 1.839-5.676), radial spasm (OR, 3.896; CI, 2.903-5.229), peripheral vascular disease (OR, 1.900; CI, 1.426-2.532), female sex (OR, 1.451; CI, 1.094-1.925), and age >80 years (OR, 1.441; CI, 1.020-2.036). Intra-arterial administration of verapamil (OR, 0.137; CI, 0.098-0.190) and nitroglycerin (OR, 0.455; CI, 0.317-0.653), and height (OR, 0.974; CI, 0.959-0.990) reduced the risk of TRF. Conclusions. Experience with TRA was associated with a low incidence of TRF. Independent factors associated with TRF were identified. 

J INVASIVE CARDIOL 2012;24(7):346-351

Key words: coronary angiography, transradial failure, learning curve

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The transradial approach (TRA) in percutaneous coronary diagnosis and intervention has become an attractive alternative to the traditional transfemoral approach. Recently, numerous studies have compared these two vascular approaches in various coronary interventions,^1-4 and patient subgroups.^5-7 Similar success rates have been reported for the two approaches, with a >70% reduction in bleeding complications^8,9 and a significant reduction in 30-day and 1-year mortality¹⁰ observed with TRA.

Despite its obvious advantages, TRA is still infrequently used in routine practice; the use of TRA in coronary interventions in the United States was only 1.32% between 2004 and 2007.⁸ Main disadvantages of TRA compared with transfemoral approach include the necessary learning curve^11-13 and a variable rate of transradial failure (TRF) due to specific problems related to this arterial access.

This single-center, prospective, transversal study was designed to evaluate the incidence and causes of TRF in coronary angiographies performed in an unselected population.

Methods

Our center is a university hospital in the Barcelona metropolitan area with a reference population of ~800,000 inhabitants. All coronary angiographies using TRA performed at the center between January 2002 and December 2009 were analyzed, excluding procedures using more than one access route (requiring bilateral injection or concomitant right catheterization) and emergency procedures. This study complies with the Helsinki Declaration and signed informed consent was obtained from all patients. Clinical variables and information about the procedure were prospectively collected. Procedures that could not be completed using the chosen access route were prospectively noted, as were the complications associated with the procedure.

An Allen test was performed on both hands prior to TRA; in uncertain cases, the permeability of the palmar arch was evaluated using plethysmography (presence of arterial blood saturation with pulse wave by occluding the radial artery). Between 2002 and 2005, TRA was only used if the Allen test was normal and the patient had a good radial pulse. After 2006, as experience accumulated, the use of TRA was extended to patients with suboptimal pulse and those with abnormal Allen tests, but plethysmography showing integrity of the palmar arch.

The procedure was initiated preferentially using the right radial artery (left radial artery was used in case of previous mammary artery graft or poor right radial pulse). After local subcutaneous anesthesia, the radial artery was punctured with a 20-gauge needle (anterior puncture method), a 0.025˝ straight-tip guidewire was inserted, a hydrophilic short sheath (10 cm) was inserted to the guidewire, followed by intra-arterial administration of 5.000 IU unfractioned heparin, 2.5 mg verapamil, and 0.2 mg nitroglycerin at the physician’s discretion. Normally, 5 Fr diagnostic catheters were used in the procedure, and the choice of catheter and size was left to the physician in charge (normally, JL 3.5 or 4, JR 4, and pigtail for ventricular angiography). Sheath was removed immediately after the procedure.

Definitions. Coronary angiography was considered successful when the angiographic images for both the right and left coronary arteries (selective or non-selective) were accurate enough to determine the presence and severity of all lesions, without requiring an alternative approach to complete the procedure.

TRF occurred when (according to operator discretion) it was impossible to complete the diagnostic study using the chosen approach, requiring a crossover to an alternate vascular approach. The final approach employed was considered the successful access for completing the procedure.

The following causes of TRF were analyzed (definitions provided in Table 1): puncture failure, tortuous brachiocephalic arteries, radial loop, radial hypoplasia or aberrant radial artery, vascular occlusion or stenosis, technical difficulty, impassable radial spasm, and vascular complications.

Other complications registered were vagal response, significant hematoma, and radial spasm. Significant hematoma was defined as a diameter >5 cm in the subcutaneous tissue, and severe hematoma in the cases that needed transfusion or surgical intervention. Radial spasm was defined as difficulty for adequate movement of the catheters and/or pain in the forearm outside of the puncture zone and/or requiring the administration of new intra-radial vasodilator medication.

Statistical analysis. Continuous variables are presented as mean ± standard deviation or median and interquartile range; categorical variables are presented as percentages.  Inter-group differences (TRF and no TRF) were examined using Student’s t-test for continuous variables, the Mann-Whitney U test was used when required, and the chi-square test for dichotomous variables. Fisher’s exact test was used when required.  Multivariate analysis using backward stepwise regression was performed for variables with a P-value <.10 in the univariate analysis. The associations of interest were summarized via odds ratio (OR) and 95% confidence intervals (CI). Statistical analyses were carried out with SPSS version 15 (SPSS Inc). Statistical significance was attained when P-values were less than .05.

Results

During the study period, a total of 11,982 diagnostic coronary angiographies were carried out; 9404 (78.5%) used TRA. Of these, 12 procedures using biradial puncture and 929 emergency procedures were excluded. The final study sample included 8463 elective diagnostic procedures using TRA (Figure 1).

Baseline characteristics and procedures were recorded for the patients included in the analysis (Table 2). As shown in Table 2, TRF routines were longer (procedure duration, 45 min vs 22 min), with longer X-ray exposure (fluoroscopy time 6.9 min vs 4.4 min) and increased contrast use (146.1 mL vs 124.7 mL). Thirty-two percent of cases had an ad hoc intervention after the diagnostic procedure and 24.7% had previous angiography using TRA, without differences in both groups. The complications associated with TRA included 41 patients (0.4%) with a significant hematoma in the puncture zone, of which only 3 required transfusion (without compartment syndrome), and 1 case of radial pseudoaneurysm that was treated with compression. Complications not associated with vascular access included 7 patients (0.1%) with a stroke, 83 patients (1%) with a vagal response, and 392 patients (4.6%) with radial spasm. None of the patients had symptoms of radial artery occlusion (RAO).

Transradial failure occurred in 465 cases (5.5%); crossover was required in 264 cases (56.8%) to transfemoral aproach, in 179 cases (38.5%) to the contralateral TRA, in 12 cases (2.6%) to the ulnar artery, and 10 cases (2.1%) required other approaches (mainly the brachial artery) (Figure 1). The causes of TRF are delineated in Table 3. The main cause was puncture failure, which happened in 48.3% of the cases. The second most frequent cause of TRF was arterial tortuosity at the subclavian artery or brachiocephalic trunk (22.8%). The remaining causes occurred at a much lower frequency.

The increase in the percentage of TRA procedures performed annually, from 43.6% in 2002 to 97% in 2009, together with the experience and skills acquired by physicians over time had a positive impact on TRF. Indeed, we observed a significant decrease in the occurrence of TRF from 9.1% in 2002 to 4.1% in 2009 (P<.001; Figure 2).

The results of the univariate analysis of the factors associated with TRF are given in Table 2. TRF occurred predominantly in women and in patients with a medical history of arterial hypertension, peripheral vascular disease, or previous coronary surgery. Procedures using the left TRA or more than 3 catheters also resulted in higher TRF rates. Intra-arterial spasmolytic medications such as nitroglycerin and verapamil were used less frequently in procedures resulting in TRF, and radial spasm was more prevalent. Procedures that required a crossover to an alternative approach were significantly longer, with a longer fluoroscopy time and greater utilization of contrast agents. We recorded a greater TRF incidence in older patients, with a significant increase from 4.2% in those under the age of 61 to 8.3% in patients >80 years of age (P<.001; Figure 3).

Multivariate analysis identified as independent factors for TRF the use of >3 diagnostic catheters, radial spasm associated with the procedure, abnormal Allen test, peripheral vascular disease, female sex, and older age (>80 years). By contrast, use of intra-radial vasodilators, such as verapamil and nitroglycerin, and height reduced the risk of TRF (Table 4).

Discussion

Our data showed that failure and complications associated with TRA in coronary angiography are low, and more importantly, we found that as experience accumulated over time TRF rates went down. The advantageous use of radial access in this unselected population has reduced the procedures performed via femoral access from over 55% in the year 2002 to a mere 3% in 2009.

Transradial failure is, without doubt, center- and volume-dependent. In our experience, the failure rate with TRA improved over time; it was over 9.1% at the initiation of the TRA program in 2002 (only 43.6% of all procedures were TRA) and was cut by half when the global percentage of TRA procedures exceeded 85%. This observation exemplifies the learning curve inherent when initiating TRA programs and the need to make TRA the elective arterial access even in unselected populations. Studies in Europe previously demonstrated this learning curve for TRA,^11-13 with decreased failure rates as centers familiarized themselves with the TRA procedure. In the United States, only 7 centers in 2007 had a volume of over 40% in TRA procedures,⁸ limiting the acquisition of experience and skilled interventionalists. The TRF rate of 5.5% in our unselected population was not greater than that observed in randomized studies. In more homogeneous populations, TRF varied between 0% and 23%, with an average of 4%-5%,^9,14 again illustrating the variations among centers and staff performing the procedure.

In this cohort, puncture failure (inability to cannulize the radial artery) was the cause of almost 50% of TRF, occurring in 224/8463 procedures (2.6%). This is a small number of the total procedures, similar to other studies with unselected patients,¹⁵ but still higher than that found in other nonrandomized studies.¹⁶ This may be due to the widespread use of radial access and the inclusion after 2006 of patients with suboptimal pulse and those with abnormal Allen tests but good radial pulse. Nonetheless, radial access in these suboptimal patients did not result in complications if the patient had a hand vascular arch integrity evaluated with plethysmography.¹⁷ In this study, unfractioned heparin was used to prevent RAO, yet we did not perform an objective assessment of RAO,^18-22 although none of our patients had signs of ischemia in the treated arm. In sum, the percentage of severe vascular complications using radial access is low and compares very favorably with femoral access.^8,9

A second group of TRF causes consisted of inability to use either radial artery as a result of anatomical anomalies of the arm and forearm, such as severe tortuosity or aberrant subclavian arteries, radial and humeral artery loops, and small radial arteries. Anatomic variations that complicate TRA previously reported^23-29 are in agreement with our findings. Although experience with TRA can, on many occasions, resolve anatomical complications through the use of specific techniques,^26,27,30 these anomalies often inevitably lead to TRF.²⁶ The most difficult anatomical variations for TRA are the radioulnar loop and the presence of a lusoria subclavian artery.²³

Factors associated with TRF. TRF occurred more frequently in older patients, as previously reported.^5,16,31 TRF increased with age, reaching 8.3% in patients over the age of 80 years, similar to other studies reporting TRF rates in these age strata between 9% and 11%.^5,30

Older, female, and shorter patients more often exhibit anatomic anomalies in the arms,²² as well as tortuous brachiocephalic arteries,³⁰ small radial arteries,²² and radial spasm.^32,33 Despite these factors, these patients benefit most from radial access because vascular complications using the femoral access are even more frequent³⁴ — up to 26% — and TRA has been shown to be an independent protection factor for these complications.⁵

Radial access permits working with smaller and unfavorable arteries with a vasoreactive component³⁵ that can further decrease the artery size. We identified radial spasm as an independent factor for TRF, and the extreme setting of impassable radial spasm was the main cause for crossover in 7.5% of TRF patients. The incidence of radial spasm found in our study was lower (4.6%) than that observed in other studies where radial spasm was defined using an automatic pullback device that calculated the force required for sheath removal (~8%)^36-38 or using a spasm score (~20%).^39,40 By contrast, similar incidences were reported in studies that used the same definition of radial spasm applied here.^41,42 The administration of intra-arterial vasodilators such as nitroglycerin and verapamil increases the radial artery size⁴³ and decreases radial spasm,^36,41,42 resulting in a beneficial effect on TRF.

Study limitations. There are limitations to this study; it is a single-center study, and emergent cases (ie, primary angioplasty) were not included. We must acknowledge that some of the variables correlating with an increased risk of TRF were simple correlates of failure, such as procedure time, contrast volume, and fluoroscopy time. Radial spasm was not assessed using more objective measures such as mechanical devices or a more complex spasm score. However, the study protocol reflects the daily practice⁴⁴ in our catheterization laboratory and the results easily extrapolate to other centers with a high volume of TRA in non-emergent percutaneous coronary diagnosis and intervention.

Conclusion

In summary, the rate of successful TRA was high in a center highly experienced with the procedure after a learning curve. The main causes of TRF included puncture failure and tortuous brachiocephalic arteries. The factors associated with TRF were peripheral vascular disease, female sex, radial spasm, and the use of multiple catheters, while intra-radial spasmolytic drugs were predictors of success in TRA procedures. TRA can and should be widely used when performing coronary angiographies because it is appreciated by the patient over femoral access, is convenient for the interventionalist and, eventually, it may be cost-effective for the institution by reducing hospital stays.^45,46 Further in-depth analysis will have to address these issues.

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From the ¹Cardiology Service, Hospital Universitari Germans Trias i Pujol, Badalona, Spain, ²Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, and ³Research Foundation Germans Trias i Pujol, Badalona, Spain.
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 December 28, 2011, provisional acceptance given February 14, 2012, final version accepted March 12, 2012.
Address for correspondence:  Xavier Carrillo, MD, Cardiology Service, Hospital Universitari Germans Trias i Pujol, Carretera de Canyet s/n 08916, Badalona (Barcelona). Email: xcarrillosuarez@gmail.com