Switching From Transfemoral to Transradial Access for PCI: A Single-Center Learning Curve Over 5 Years

Abstract: Background. Percutaneous coronary intervention (PCI) via the transradial (TR) route is an increasingly popular alternative to the transfemoral (TF) route. However, there are limiting factors to its adoption. We report the learning curve over 5 years in a high-volume PCI center during the crossover from TF to TR access for PCI. Objective. To evaluate clinical characteristics, radiation doses, screening times, and subsequent clinical outcomes in subjects with femoral and radial access sites for PCI. Design. We retrospectively analyzed our databases for PCI procedures/outcomes of all patients from 2006-2010. Setting. A university teaching hospital PCI center performing cases predominantly femorally at the beginning of the study period, and transitioning to a predominantly radial access center at the end of the study period. Patients. All patients undergoing PCI via either femoral or radial approach over a 5-year period. Results. In year 1, TR access was used in 31.4% of cases; this rate increased to 90.1% in year 5. The switch from TF to TR access was observed among all operators and all groups of patients regardless of presentation, gender, age, and lesion complexity. In year 1, fluoroscopy times and radiation doses were higher in the TR group, but equalized in years 2 and 3 and reversed during years 4 and 5 when the TR rate was >90%. Over 5 years, the rates of vascular complications and major bleeding were higher in the TF cohort and were associated with longer hospital stay. In-hospital mortality was lower in the TR group. Conclusion. The change from TF to TR approach for PCI in a high-volume center is achievable within 5 years, and results in marked clinical benefits. There was an initial learning curve for fluoroscopy time and radiation dose, but this improved once an operator performed >60% of cases radially.

J INVASIVE CARDIOL 2014;26(10):535-541

Key words: radial access, vascular complications, radiation exposure

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While percutaneous coronary intervention (PCI) via the transradial (TR) route has been shown to reduce the length of in-hospital stay,^1-3 risk of periprocedural bleeding⁴ and access-related vascular complications,^1,5-7 it remains underutilized in current clinical practice worldwide when compared to the traditional transfemoral (TF) route.⁸ The main factors limiting its adoption in TF centers have been attributed to the steep learning curves in switching over to TR access, high TR to TF crossover rates, technical aspects of TR-PCI, prolonged procedure times, and increased operator radiation exposure.^9-13 While single-center studies carrying out coronary angiography and/or PCI have reported that transition of TF to TR route is associated with increased fluoroscopy and procedure times,^14,15 there are limited published data available on the time taken to achieve the transition from a TF-PCI center to a TR-PCI center. We hereby report an observational study on the transition in practice in a single high-volume PCI center in the United Kingdom from a majority TF-PCI center to a majority TR-PCI center.

Methods

From January 1st 2006 to December 31st 2010, a total of 6575 patients underwent PCI. TF-PCI was performed using 6 Fr, 7 Fr, or 8 Fr sheaths, while TR-PCI used 5 Fr, 6 Fr, 7 Fr, or 8 Fr sheaths. For TR-PCI procedures, collateral circulation in the hand was confirmed using the Allen’s test or by detection of a normal arterial waveform using pulse oximetry after radial artery occlusion by manual pressure. The decisions to treat native vessel or bypass grafts, choice of stent, use of glycoprotein IIb/IIIa inhibitors, vascular access, use of distal protection devices in vein-graft PCI cases, and the use of diagnostic devices during the procedures were all left to the discretion of the operator. All patients received dual-antiplatelet therapy (aspirin and clopidogrel or aspirin and prasugrel) and an intravenous bolus injection of unfractionated heparin (70 Units/kg body weight) before the procedure regardless of access route. Significant stenosis was defined as any lesion of a major epicardial artery or branch vessel or graft (≥2.0 mm in diameter) that had ≥50% lumen stenosis on angiographic assessment. Procedure success was defined as <50% stenosis in all lesions attempted without the occurrence of any major immediate complications (death, Q-wave myocardial infarction [MI], emergency coronary artery bypass graft [CABG]). Q-wave MI was defined as the development of new Q-waves associated with an elevation of cardiac troponin T after PCI. No/slow reflow was defined as TIMI flow grade of ≤1 that was not due to a dissection or high-grade residual stenosis within the target lesion. Major bleeding (not related to CABG) was defined as intracranial bleeding, access-site bleed resulting in a hematoma ≥5 cm or requiring intervention/surgery, hemoglobin decrease by ≥3 g/dL with an overt source or by ≥4 g/dL without an overt source, any blood product transfusion, or reoperation for bleeding.¹⁶ All complications were blindly adjudicated in house by three individuals. 

Patients undergoing TR-PCI received 100 µg of isosorbide dinitrate and/or 2.5 mg verapamil in the arterial sheath. Following PCI, patients undergoing TR-PCI had the radial sheath removed in the catheterization laboratory where hemostasis was achieved by using a TR band (Terumo Medical Corporation) with an inflated balloon. The balloon was gradually deflated after 1 hour and then every 15 minutes, monitoring for bleeding and access-site complications. The right radial approach was used in >90% of all radial cases; the exceptions were cases where there was a poor right radial pulse in patients having a second radial procedure or performing a saphenous vein graft (SVG) case where accessing the left internal mammary artery (LIMA) graft was part of the procedure. Patients undergoing TF-PCI underwent femoral arteriography, after which a closure device was deployed as per the discretion of the operator. Manual pressure hemostasis was achieved after sheath removal once the activated clotting time was <200 seconds. The TF access site was also monitored for hematoma and vascular complications. Patients undergoing PCI via the transbrachial route (<5 cases/annum) were the only patients excluded in that time period. All data were collected from the University Hospital of Wales internal databases and subsequently cross-referenced with the national British Cardiovascular Intervention Society (BCIS) for long-term mortality tracking. Demographic, clinical, and angiographic data for frequencies and continuous variables are presented as mean values ± standard deviation and categorical variables as frequency (%). Continuous variables were compared using the independent variable t-test and categorical variables using chi-squared statistics. A P-value of <.05 was considered statistically significant and all reported P-values are two tailed. Statistical analysis was performed using SPSS version 16 for Windows (SPSS, Inc).

Results

Patient population. From January 2006 till December 2010, PCI procedures increased from 1026 to 1420 per annum accompanied by a change in access-site practice from TF-PCI to TR-PCI in both males and females. The adoption of the TR approach was slower in females in the first 3 years (Figure 1). Patients undergoing TR-PCI were younger by 2010 as compared to the 2006 cohort. There was no difference in the prevalence of the cardiac risk factors in either cohort over the 5 years, although there was a tendency of patients with renal impairment to undergo PCI via the TF route (Table 1).

Indications and technical aspects of PCI procedure. A significant trend in the transition of TF-PCI to TR-PCI was observed in patients undergoing PCI to native coronary lesions, saphenous vein grafts, and chronic total occlusions (Figure 4). This trend was also observed in the entire population presenting with cardiac ischemia, ie, stable angina, acute coronary syndromes, and those undergoing primary PCI for ST-elevation MI (Figure 3 and Table 2). Glycoprotein IIb/IIIa use was similar in both cohorts in 2006, but was used predominantly in TR-PCI cases by 2010, which reflects the increased adoption of the TR approach. Similarly, bivalirudin was sparingly utilized but was used predominantly in the TR-PCI cohort by 2010 as well. With regard to the technical aspects of the PCI procedure, there was a similar trend seen in cases requiring intravascular ultrasound, fractional flow reserve, and thrombus aspiration. These data reflect the wholesale adoption of the TR approach rather than a specific device-related choice of access route. This was not evident where rotational atherectomy, cutting balloon, or distal protection devices were used (Table 3), where the use of these adjuvant interventional devices increased more slowly in cases done radially.

PCI outcomes. PCI success rates in both cohorts were comparable, with TR-PCI becoming more favored over the 5-year period. There was, however, a significant change in crossover rates in patients undergoing TF-PCI (femoral to radial crossover) as compared to those undergoing TR-PCI (radial to femoral crossover) during the 5-year period. The total radiation dose was initially higher in the TR-PCI cohort in year 1, but this was similar in both cohorts by 2010 (Figure 5). Fluoroscopy time was significantly higher in the TR-PCI group in 2006, but this reversed by 2010, when patients undergoing TF-PCI required longer fluoroscopy times to complete the procedure. There were no differences in coronary complications (coronary dissection, no/slow flow, arrhythmias, shock induced by procedure, Q-wave MI, and cerebrovascular accidents/transient ischemic attacks) in either cohort during the 5-year period. Cumulatively, patients undergoing TF-PCI had significantly higher rates of access-related vascular and bleeding complications. In-hospital mortality rates were comparable in both cohorts initially, although there was a reduction of in-hospital mortality in the TR-PCI cohort over 5 years. The length of in-hospital stay was longer in the TF-PCI cohort whether the patients underwent PCI for stable angina or an acute coronary syndrome (Table 3). 

Discussion

This study reports the learning curve from a high-volume PCI center over 5 years during the switch from TF to TR access site. Although observational, our results confirm the recognized benefits of TR-PCI in reducing vascular complications, bleeding, and in-hospital stay.^1,2,4 Importantly, these data show that a high-volume radial operator decreases fluoroscopy time and radiation dose as experience is gained, and contributes to the existing literature by documenting patterns of practice that can be anticipated in existing TF centers contemplating a change to TR access for PCI. 

Radiation exposure and fluoroscopy times were significantly increased in the TR-PCI cohort in the first year. However, by years 2 and 3, radiation exposure and fluoroscopy times were similar and by year 5, this finding was reversed once an operator performed over 60% of cases radially. These findings support the existing literature reporting increased operator and patient radiation doses in the early part of the TR learning curve, but reveals that this achieves parity and shows reversal with increased TR experience. However, it is possible that the higher screening times and radiation doses in year 5 with the TF approach may indicate a preference for TR operators to undertake complex PCI, chronic total occlusions, and retrograde approaches femorally. Several authors have reported increased radiation dose with TR access, and this has been one of the factors limiting the switch to TR access in established TF operators.¹⁰ There are no published head-to-head data of radiation dose in high-volume TF and TR operators. Our data are unique in that they compare the same operators when they were predominantly using TF to when they were predominantly using TR. Our findings suggest that increased fluoroscopy time and radiation dose are a function of the learning curve in switching to radial access, but this difference is reversed in favor of TR access once an operator is performing >60% of cases radially.

Based on our study population, the transition to TR-PCI over 5 years was both feasible and safe. Transition to TR access was slower in females and most likely reflects operator discretion given the smaller-caliber radial arteries in women.¹⁷ Paradoxically, given the higher access-site bleeding rate in women, the benefits of TR-PCI are more likely to be seen in the female population presenting with acute coronary syndromes,^18,19 and our study reveals that this benefit will only be seen at a later stage of the transition period. Patients undergoing TR-PCI were also found to have a higher body mass index in the first year, but this difference was not seen thereafter, suggesting a possible operator bias when adopting the TR-PCI, given the increased risk of femoral complications in this cohort initially. Similarly, adoption of TR-PCI was more prevalent in a younger age group in the early phase, whereas patients with renal impairment were more like to have PCI performed via the TF route. These trends are similar to the information reported previously by the North American National Cardiovascular Data Registry.⁸ 

Our study also showed that the transition of TF-PCI to TR-PCI in the treatment of native coronary artery lesions was more rapid than in the treatment of SVG lesions. This  finding is explained by operator bias in selecting femoral access in patients with previous CABG.²⁰ However, as TR-PCI to SVG lesions continues to show similar success rates as compared to the TF-PCI route,^21-23 TR-PCI operators are taking on more SVG-PCI lesions via the TR route. A similar trend is also seen in patients undergoing PCI to chronic total occlusions, where operators predominantly undertook these complex cases via the TR route in the later years. Although femoral access has been traditionally used for the retrograde approach,^24-26 some centers are adopting biradial arterial access to attempt PCI via the retrograde route²⁷ and  are reporting comparable success rates. Our study reflects this trend of practice in preferably adopting the TR route to treat both simple and complex lesions. 

We observed a slower transition in adopting the TR-PCI technique for primary PCI in the treatment of ST-elevation MI. This could reflect concerns of a longer procedure time in gaining arterial access by operators early in their learning curves. While rapidly establishing TIMI-3 flow in the infarct-related artery remains the cornerstone treatment of ST-elevation MI,^28-30 several studies have shown that the TR route for primary PCI confers advantages in terms of bleeding risks and vascular complications at the expense of an insignificant longer time to gain TR access.^31-33 Glycoprotein IIb/IIIa inhibitors were increasingly used in the TR-PCI population, reflecting the change in practice where maximal benefits of potent antiplatelet agents can be exploited when patients undergo PCI via the TR route with significantly lower bleeding risk. However, the introduction of bivalirudin led to a reduced use of glycoprotein IIb/IIIa inhibitors in the last 2 years.³⁴ The use of fractional flow reserve wires and intravascular ultrasound was prevalent in TR-PCI cases, supporting the idea that there are no technical difficulties in making use of these devices when PCI is performed by the TR route. The use of thrombus aspiration catheters mirrored that of primary PCI, where cases were performed predominantly via the TR route by year 4. However, we found no significant trend in the use of cutting balloons and rotational atherectomy devices in the TR-PCI cohort. This could be explained by the need for larger guide catheters to accommodate higher-profile cutting balloons or rotablator burrs, as well as to provide for additional guide-catheter support in the treatment of heavily calcified coronary lesions. 

The PCI outcomes showed comparable success rates, slightly favoring the TR-PCI route when the cumulative data over 5 years were analyzed. This discrepancy could be explained by the relatively larger number of TR-PCIs done over the 5 years compared with TF-PCI cases. Operator bias may play a role in favoring the TF route for very complex PCI cases and thereby explain the lower PCI success rates. Included in this potential high-risk case mix for TF cases are cardiogenic shock cases and intra-aortic balloon pump cases, which have the potential to confound length of stay figures in the latter years. We also noticed a significant crossover rate from TR-PCI to TF-PCI in the early stages of the transition, but the rates were significantly reversed the end of the study period, thereby supporting that transitioning from TF-PCI to TR-PCI results in temporarily increased TR to TF crossover rates. This supports the principle that the TR-PCI technique can be indefinitely maintained. 

While periprocedural complications were similarly prevalent in both cohorts, the additional advantage that TR-PCI carries is the reduced risk of vascular and bleeding complications, as well as a reduction in hospital stay. Transitioning from a TF-PCI to a TR-PCI center resulted in reduced in-hospital stay and PCI-related vascular/bleeding complications, and similar success rates. This facilitates the provision of a same-day discharge PCI service for elective PCI via the radial route, with 0.4 days the average length of stay for stable patients after PCI. Finally, cumulative mortality was significantly lower in the radial group compared to the femoral group. This mortality was only demonstrated over the 5 years and is likely to be multifactorial. An improvement in vascular complications and bleeding may play a part; it is also possible that the mortality gain is realized by femoral case selection in years 4 and 5, when the 10% of cases performed by now default radial operators were the highest-risk cases, such as those with cardiogenic shock and the elderly. 

Conclusion

The results of our observational study confirm that the adoption of the TR-PCI technique in a preexisting TF center is both feasible and accrues clinical benefits. With comparable success rates, the adoption of TR-PCI results in a significant reduction of access-related vascular complications, bleeding, and shorter in-hospital stay. Although the initial phase of the transition from TF-PCI to TR-PCI center is associated with increased fluoroscopy times and radiation exposure, this phenomenon is reversed when the majority of PCI cases are done predominantly via the TR route and operators have passed through their learning curve. 

Study limitations. This is a single-center study; therefore, the findings may not be replicated in other centers with lower annual PCI volumes, since the learning curve may be extended further in such centers. Cases done femorally in the latter years (<10% of all cases) seem to integrate some of the patients who were significantly older, more likely to exhibit cardiogenic shock and require complex PCI including rotablation, etc, so radiation doses, fluoroscopy times, and mortality results may be confounded by this in years 4 and 5. However, overall, these results offer important insights into changing from a predominantly TF center to a predominantly TR center, and once again demonstrate the realizable clinical benefits.

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From the ¹University Hospital of Wales, Cardiff, Wales, United Kingdom; and the ²Freeman Hospital, Newcastle, United Kingdom.

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 October 7, 2013, provisional acceptance given December 16, 2013, final version accepted April 21, 2014.

Address for correspondence: Richard A. Anderson, MD, Cardiology Department, University Hospital of Wales, Cardiff, CF4 4XW, United Kingdom. Email: Richard.Anderson@wales.nhs.uk