Operator and Institutional Experience Reduces Room-to-Balloon Times for Transradial Primary Percutaneous Coronary Intervention

Abstract: Background. Transradial (TR) access for primary percutaneous coronary intervention (PCI) is becoming accepted as the preferred approach but has not gained widespread adoption due to technical challenges that may limit procedural success and delay time to revascularization, particularly among patients treated by inexperienced operators. We report our experience over the first 2 years of our TR primary PCI program and determined the impact of TR access on clinical and procedural outcomes. Methods. Clinical characteristics and procedural outcomes were collected prospectively from 488 patients presenting with ST-segment elevation myocardial infarction and compared according to whether patients underwent primary PCI via the TR or transfemoral (TF) approach. Results. Hospital mortality was very low in both groups (1.1% [TR] vs 2.6% [TF]; P=.23). Access-site intended procedural success for primary PCI was equivalent (98.4% for TR vs 98.6% for TF; P=.85). Catheterization room-to-balloon (RTB) times were significantly lower among patients undergoing TR primary PCI as compared with those in the TF group (20:33 ± 06:41 [TR] vs 25:11 ± 08:22 [TF]; P<.001). TR patients treated by operators who had performed >50 TR PCIs had lower RTB times (20:03 ± 06:12 vs 24:26 ± 10:01; P<.06) and lower doses of radiation exposure (1812 ± 1007 mGy vs 2827 ± 954 mGy; P<.01) than patients treated by less experienced operators. Dual-purpose guide catheter usage was also associated with lower RTB times (18:38 ± 5:42 vs 25:15 ± 8:20; P<.001) and radiation exposure (1824 ± 6205 mGy vs 2407 ± 1389 mGy; P<.01). Conclusions. TR primary PCI may be performed rapidly and successfully despite only modest operator and institutional experience.

J INVASIVE CARDIOL 2014;26(2):80-86

Key words: : primary angioplasty, acute MI, radial artery intervention, vascular access 

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The transradial (TR) approach for coronary angiography and revascularization is gaining broader acceptance due to improved outcomes, including reductions in vascular access-site complications and bleeding as compared with transfemoral (TF) procedures.^1-5 These advantages are greatest among patients presenting with ST-segment elevation myocardial infarction (STEMI), wherein the TR approach may also confer a mortality advantage.^6,7 However, the adoption rate for this technique has remained low, particularly in the United States, due to operator inexperience as well as disappointing rates of procedural failure and access-site crossover even among operators with extensive experience.^6,8-11 Inexperienced operators may therefore be reluctant to convert to the TR approach for time-sensitive procedures out of concern for procedural failure or delays.   

Our objectives were to institute a TR-STEMI program despite having only modest urgent and elective TR experience and to evaluate procedural success, complication rates, and revascularization times over the course of 2 years. In order to optimize success, we implemented specific measures to overcome challenges related to vascular access, radial arterial spasm, and coronary intubation and support.¹² Importantly, we started our program despite only modest institutional and operator experience, and we report our outcomes including catheterization suite room-to-balloon (RTB) times in patients undergoing both TR and transfemoral (TF) primary PCI.

Methods

Study population and definitions. The study population consisted of 488 consecutive patients presenting or transferred to UMass Memorial Health Center within 12 hours of STEMI onset who underwent primary PCI from November 1, 2009, through October 31, 2011. Two patients were excluded due to presentation in a comatose state, 1 patient was excluded due to prolonged and ongoing cardiopulmonary resuscitation, and 6 patients were excluded due to an inability to clearly identify the culprit artery. For the purposes of comparing RTB times, 19 patients (2 TR and 17 TF) were excluded due to non-PCI related delays, including the need for temporary transvenous pacing, aortic counterpulsation, resuscitation, or intubation.

Clinical and procedural data and outcomes were collected until the time of hospital discharge. Patients were divided into TR and TF groups according to the initially intended access site, and clinical and procedural outcomes were compared. Cardiogenic shock was defined as a condition of end-organ hypoperfusion with a systolic blood pressure below 90 mm Hg requiring vasopressors or aortic counterpulsation and was adjudicated by the Massachusetts Data Analysis Center PCI Data Adjudication Committee (https://www.massdac.org/CommPCIAdjudication). The study was approved by the University of Massachusetts Medical School Committee for the Protection of Human Subjects in Research.

Primary PCI procedure. First responders and physicians from either referring or UMass Memorial Emergency Departments were enabled to activate the STEMI system and to consult the interventionalist for further direction of care. Patients received 325 mg aspirin and either 600 mg clopidogrel or 60 mg prasugrel, along with 5000 units unfractionated heparin prior to entry into the catheterization suite. The use of glycoprotein IIb/IIIa inhibitors, direct thrombin inhibitors, and additional antithrombin agents was at the discretion of the operator. All procedures utilized standard techniques and were accomplished with 6 Fr diagnostic catheters or guide catheters. Ventriculography was performed at the operator’s discretion.  

Patients undergoing TR procedures were required to have a Barbeau grade A-C for the access site selected.¹³ Transradial access was obtained with a 22 gauge needle and 0.22˝ straight guidewire, whereupon a 250 mm hydrophilic sheath (Terumo Corporation) was inserted. Nitroglycerin (100-200 µg) was infused intraarterially if vasospasm was encountered, but was not administered routinely. Upon completion of the procedure, a TR band (Terumo Corporation) was applied to achieve patent hemostasis. The air bladder was deflated according to an activated clotting time (ACT)-based algorithm beginning at 1 hour for ACT ≥225 seconds and at 45 minutes for ACT <225 seconds. Standard techniques were employed for transfemoral procedures. Hemostasis was achieved either manually or with Perclose (Abbott Vascular) or Angio-Seal (St Jude Medical) devices. 

Catheters employed for angiography and PCI of the left coronary artery from the right TR approach included Jacky Radial, TIG (Terumo Corporation); Judkins left (JL), JCL, JCL Radial, Extra Backup (EBU), Amplatz left (AL), and MAC (Medtronic). Catheters used for engaging the right coronary artery from the right TR approach included Jacky Radial, TIG; Judkins right (JR), Amplatz right (AR), AL, and MAC. Standard catheters were used for TR procedures performed from the left radial artery and for procedures from the femoral approach.

Selection of the arterial access site was obtained at the operator’s discretion. The five interventionalists performing the TR and TF procedures are high-volume operators with volumes ranging from 200-400 PCIs annually. Five months prior to commencement of our TR-STEMI program on November 1, 2009, a concerted effort was undertaken to increase institutional elective and urgent TR volume. Operators were encouraged to transition to TR access for primary PCI after commencement of the TR-STEMI program on November 1, 2009.  

To determine whether institutional experience impacted TR time to revascularization, RTB times were plotted at 3-month intervals. The steep portion of the learning curve was identified and patients were then divided into early and established groups for further comparisons. For purposes of comparing outcomes according to procedural volume during the established phase, operators were divided into those having performed 51-100 TR PCIs (n = 2) prior to transitioning to TR primary PCI and those who had performed 50 or fewer TR PCIs (n = 3).

Outcomes. The primary outcomes of the study were catheterization RTB times, procedural success, and access-site intended procedural success. Room-to-balloon was defined as the difference between entry into the catheterization suite and the time to delivery of the first interventional device. RTB times were further divided into room-to-arterial access (RTA) and arterial access-to-balloon (ATB) times. Procedural success for PCI was defined as successful reperfusion of the infarct-related artery with TIMI-3 flow and <30% residual stenosis. Catheter-specific procedural success was defined as success with PCI and/or completion of angiography with the chosen catheter. Catheter types utilized for fewer than 5 procedures were not included in the analysis pertaining to catheter-specific procedural success.  

Clinical outcomes included vascular complications requiring intervention, loss of access-site pulse, access-site and non-access site severe bleeding (defined as a decline in Hgb ≥3 g/dL or need for transfusion), stroke including intracranial hemorrhage (ICH), radiation exposure, contrast volume, catheter-induced coronary artery dissection, and death.  

Statistical analysis. Continuous variables are reported as the mean ± standard deviation (SD) and time intervals as the median ± SD. Comparisons were conducted using ANOVA (P<.01) and Student’s t-test with Bonferroni correction when comparing multiple groups. Categorical variables are reported as absolute values with percentages and compared with Chi-square analysis. A P<.05 was considered significant.

Results

Study population. Table 1 summarizes the clinical characteristics of the 488 patients who presented with STEMI and underwent primary PCI. Patients undergoing TR primary PCI were more frequently male and were less likely to have had a prior history of coronary artery disease (CAD). Fewer TR patients required aortic counterpulsation or presented in cardiogenic shock. Angiographic characteristics were the same between the groups with the exception that more patients in the TR group underwent primary PCI for stent thrombosis (Table 2). The differences between the TF and TR groups persisted after excluding patients with non-PCI related procedural delays.

Hospital mortality was very low in both groups. One patient in the TR group died as a result of an intracranial hemorrhage (ICH) due to profound thrombocytopenia related to chronic liver disease; the other patient declined surgery for a contained left ventricular rupture. One patient in the TF group died intraoperatively during emergent coronary artery bypass surgery performed for incomplete percutaneous revascularization. Care was withdrawn in a second patient after declining surgical intervention for access-site bleeding related to aortic counterpulsation. The remaining patients in the TF group died due to persistent left ventricular dysfunction or ventilator-associated pneumonia. 

Vascular complications were very low and equivalent between the two groups. A trend toward fewer access-site bleeding events appeared within the TR group (Table 1). One patient in the TR group experienced an ICH as previously noted, and 1 patient in the TF group required surgical intervention for loss of pulse.   

Effect of access on procedural metrics. Within the TR group, the right rather than left radial artery was selected for access in 173 patients (94%). Contrast volume, radiation exposure, PCI procedural success, and access-site intended PCI procedural success were equivalent between the TR and TF groups. Only 2 patients (1.1%) crossed over from TR to TF access, neither of them as a result of subclavian tortuosity or inadequate guide catheter support. TR access could not be obtained in 1 of these 2 patients and resulted in a 15-minute procedural delay. Severe brachial artery spasm prevented trafficking of the coronary catheter beyond the upper arm in the second patient, resulting in a 4-minute delay. Both procedures were completed successfully from a TF approach. One patient (0.4%) crossed over from TF to a transbrachial approach due to occlusion of the left common iliac artery, resulting in a 38-minute delay.

Room-to-balloon times were significantly lower among patients undergoing TR primary PCI compared to the TF group (21:10 ± 07:02 vs 24:51 ± 08:30; P<.001; Table 2). While RTA times were equivalent (10:40 ± 04:15 vs 11:03 ± 04:02; P=.32), ATB times were significantly lower in the TR group (09:52 ± 05:40 vs 13:15 ± 08:06; P<.001).  

Effect of institutional experience on procedural metrics. To determine whether institutional experience impacted TR revascularization times, RTB times were plotted and revealed a steep decline over the first 8 months of the program, corresponding to the first 35-40 procedures. A relatively low proportion of patients underwent TR PCI during this early phase (Figure 1). Data from the early period revealed that RTB times were equivalent between the TR and TF groups (23:41 ± 07:58 vs 24:35 ± 08:37; P=.55). We further analyzed data from this early period and determined that RTB times were significantly lower when non-culprit (NC) vessel angiography was deferred until after completion of TR primary PCI (24:35 ± 08:37 [TF] vs 25:44 ± 08:22 [TR NC immediate] vs 18:19 ± 02:50 [TR NC deferred]; P<.01; Figure 2). This difference in RTB time was due entirely to lower ATB times favoring deferred NC vessel angiography (13:26 ± 08:11 [TF] vs 14:46 ± 06:04 [TR NC immediate] vs 9:12 ± 03:03 [TR NC deferred]; P<.01), as RTA times between the groups were equivalent (P=.37).  

RTB times in the TR group decreased after the early phase of the program, such that RTB times during the established phase were significantly lower in the TR group compared to the TF group (20:33 ± 06:41 vs 25:11 ± 08:22; P<.001; Figure 2). This decline in TR RTB times was in part due to a decrease in the proportion of patients undergoing NC vessel angiography prior to PCI (72% vs 38%; Chi²<0.001). Although lower RTB times were associated with fewer patients undergoing early NC vessel angiography, the decline in RTB times was also associated with a decrease in catheter manipulation times in patients undergoing NC vessel angiography immediately prior to PCI (25:11 ± 08:22 [TF] vs 21:15 ± 07:36 [TR NC immediate] vs 20:08 ± 06:04 [TR NC deferred]; P<.01; Figure 2). Likewise, ATB times were lower in both TR groups as compared with TF patients (13:01 ± 08:02 [TF] vs 10:46 ± 06:32 [TR NC immediate] vs 07:54 ± 04:09 [TR NC deferred]; P<.01).  

Effect of operator experience on procedural metrics. To determine the impact of operator volume on procedural metrics, patient outcomes were compared during the established phase according to whether the operator had performed greater than or fewer than 50 TR PCIs prior to transitioning to the TR approach for primary PCI. Time intervals were equivalent between the more and less experienced operators when NC vessel angiography was deferred until after completion of the PCI (Table 3). In contrast, patients undergoing NC vessel angiography prior to PCI by the more experienced operators had lower ATB times (9:52 ± 4:50 vs 13:48 ± 9:00; P=.04), whereas RTA times were similar (9:48 ± 2:35 vs 10:04 ± 2:36; P=.73). Contrast volume and radiation exposure were significantly lower in patients treated by the more experienced operators, particularly in patients undergoing immediate NC vessel angiography. These findings were associated with more frequent use of dual-purpose guide catheters by the more experienced operators (73% vs 33%; Chi²<0.01).

Effect of catheter selection on procedural metrics. We investigated the impact of selective and dual-purpose coronary catheter usage on RTB times and procedural outcomes over the 2-year study period. For the left coronary artery, the JCL and JCL Radial catheters were highly successful for both angiography and PCI (Figure 3A). For the right coronary artery, the JR and AR catheters were most successful for both angiography and PCI (Figure 3B).

Operators performed angiography and PCI in 45 patients with the intention of completing the entire procedure with a single guide catheter (MAC [n = 8]; Kimny [n = 1]; JCL Radial [n = 34]; and AL [n = 2]) and were successful in 29 patients (64%). When comparing patients undergoing immediate imaging of the NC vessel, RTB (18:38 ± 05:42 vs 25:15 ± 08:20; P<.001) and ATB times (8:46 ± 04:50 vs 14:11 ± 06:38; P<.001) were significantly lower when a single catheter strategy was employed. Likewise, radiation exposure as determined by dose area product (13908 ± 6205 cGycm² vs 18575 ± 9998 cGycm²; P<.05) and total exam dose (1824 ± 6205 mGy vs 2407 ± 1389 mGy; P<.01) were also significantly lower with the use of a single catheter.

Discussion

This is the first study to report very low crossover rates with lower times to revascularization in patients undergoing primary PCI via TR as compared with TF access despite only modest institutional and operator experience. By utilizing long sheaths and contemporary coronary catheters, operators at our institution were able to limit the impact of radial artery spasm, subclavian tortuosity, and difficulty with catheter manipulation on successful and rapid coronary reperfusion.  

The TR approach for coronary catheterization and percutaneous revascularization is becoming preferred due to reductions in bleeding and vascular complications as compared with TF procedures.^1-5 These advantages are particularly important for patients presenting with STEMI, and recent studies have suggested a mortality advantage with TR PCI in these high-risk patients.⁷ Widespread adoption of this technique has been limited due to technical challenges and lack of experience among most interventionalists. However, refinements in sheath and catheter design have aided in overcoming many of the technical challenges and disadvantages associated with TR procedures.¹⁰  

We report findings from our 2-year experience with TR primary PCI. Importantly, none of the five operators had performed more than 100 TR-PCIs prior to commencement of our TR-STEMI program. Our study shows that TR-PCI may be performed with a high rate of success, a very low crossover rate, and rapid RTB times despite only a modest level of operator experience. Additionally, RTB times may be accelerated and contrast volume and radiation exposure reduced once operators become facile with employing dual-purpose coronary guide catheters.  

Transradial primary PCI and its impact on time to revascularization have been reported previously. Hetherington and Arzamendi independently found that patients undergoing TR primary PCI had equivalent needle-to-balloon times as compared with TF primary PCI patients; however, TR patients had significantly higher crossover rates.^8,11 Similarly, Weaver demonstrated more favorable revascularization times, but a higher crossover rate with TR procedures.¹⁰ More recently, Larsen reported RTB times that were similar to their prior TF experience (30 minutes) and a favorable TR primary PCI crossover rate (1.2%).¹⁴ Our findings contrast with prior studies by showing that both crossover rates and revascularization times may be very low with TR primary PCI despite only modest operator experience.  

Our low crossover and high procedural success rates likely are the result of many factors. Vasospasm was responsible for crossover in only 1 patient, whereas the other patient crossed over prior to successful radial artery cannulation. This low rate of vasospasm likely relates both to our use of long sheaths as well as patient selection prior to catheterization suite entry.^15,16 Patients more prone to spasm, including smaller women, may have been declined TR primary PCI due to poor radial pulses. Interestingly, subclavian tortuosity was not a factor in limiting procedural success. This finding is not merely related to the relatively young patient population presenting to our institution with STEMI, but rather is also due to our use of contemporary equipment designed for ease of coronary intubation and support for PCI.    

We found that institutional experience was important early in our program and related primarily to a collective understanding of catheter selection and timing of NC vessel angiography. During the early period of our program, operators were concerned that TR RTB times were relatively prolonged due to delays related to imaging the NC vessel prior to PCI. In order to accelerate time to reperfusion during the established phase, operators adopted strategies of either deferring NC vessel angiography until after revascularization or performed immediate NC vessel angiography more expeditiously by utilizing dual-purpose coronary guide catheters. More experienced operators were more likely to employ dual-purpose coronary catheters, explaining at least in part why radiation exposure was inversely related to operator experience as has been seen in other studies.¹⁷ Importantly, RTB time was not delayed in TR patients treated by the less experienced operators relative to TF patients.

Delaying NC vessel angiography until after culprit vessel revascularization is controversial. Identification of the culprit vessel may require acquisition of complete angiographic data, and the presence of surgical disease may influence decisions related to the index PCI, such as stent type or use. Importantly, patient care in our study was not altered as a result of delayed angiography of the NC vessel, findings that are consistent with a prior study showing that RTB times may be accelerated without compromising patient care by deferring NC vessel angiography.¹⁸ The small but measurable decrease in time to revascularization obtained by delaying NC vessel angiography likely does not outweigh the value of the information gained with immediate NC angiography. As operators gain experience and transition to using dual-purpose guide catheters, angiography of the NC vessel may be performed prior to PCI without sacrificing RTB time.  

Few patients, particularly in the United States, undergo TR primary PCI despite accumulating evidence showing advantages over the TF approach. Inexperienced operators remain reluctant to transition to the TR approach due to concerns related to a reduction in procedural success from inherent challenges related to arterial access, subclavian tortuosity, and guide catheter seating and support. Although none of our operators had performed over 100 TR PCIs, our program has been successful due to our ability to address technical complexities through the use of contemporary equipment. Most catheters used via the TR approach in this study may also be employed for TF procedures, enabling operators to become accustomed to catheter manipulation technique before transitioning to the TR approach. Additional catheter refinements or the use of other currently available guides may further enhance technical success and shorten the expected learning curve for operators with limited TR experience.

Patients undergoing TR procedures shared characteristics similar to those in other TR primary PCI studies, namely, a higher proportion of men and fewer patients presenting with cardiogenic shock requiring aortic counterpulsation.^5,7,10 We attribute the relatively low use of stents in our study to the significant proportion of patients presenting either with stent thrombosis or with concomitant multivessel or left main coronary artery disease requiring subsequent surgical revascularization. Our study was unable to detect a difference in mortality due in part to an observed mortality rate that was low as compared with our expected mortality.¹⁹ We attribute our low observed mortality to strict adherence to published guidelines, accelerated times to reperfusion, and advanced care following completion of the primary PCI. 

Study limitations. As with any non-randomized study, bias related to patient selection for the TR and TF groups may have been introduced. It is likely that some patients with poor radial pulses, including patients presenting with cardiogenic shock or smaller women, were more likely to undergo TF PCI. When transitioning from the TF to the TR approach, operators are encouraged to select lower-risk patients for TR primary PCI until adequate experience is attained. We report our real-world experience demonstrating successful and rapid reperfusion from the TR approach but maintain that the TF approach may be more appropriate for complicated or hemodynamically unstable patients, particularly at institutions with limited TR experience. Clinical pulse assessment rather than ultrasound was utilized for the purpose of detecting flow within the radial artery until hospital discharge. It is possible that radial artery occlusion reporting rates would have been higher had ultrasound been employed.

Conclusion

Our study demonstrates that TR primary PCI may be achieved rapidly and with a high rate of success in selected patients, despite only modest operator and institutional experience. Use of contemporary TR equipment may accelerate the learning curve, enabling more widespread adoption of this important technique.

References

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From the University of Massachusetts Medical School, Cardiovascular Division, Worcester, Massachusetts.

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 August 1, 2013, provisional acceptance given September 9, 2013, final version accepted October 7, 2013.

Address for correspondence: Kurt G. Barringhaus, MD, FSCAI, Cardiovascular Division, University of Massachusetts Medical School, S3-853, 55 Lake Avenue North, Worcester, MA 01655. Email: Barringk@ummhc.org