It’s Time to Get With The Guidelines: The AHA Scientific Statement in Support of Transradial Artery Access for Coronary Angiography and Percutaneous Coronary Intervention in Acute Coronary Syndromes

Over the past two decades, transradial artery access (TRA) in coronary angiography and percutaneous coronary intervention (PCI) has transformed from a niche concept to an established technique with proven benefits. While early studies of TRA showed promise, they were limited by relatively small sample sizes and lacked bleeding avoidance strategies in the control femoral access arm. These limitations impeded the inclusion of TRA for reducing complications in past American professional society guidelines on PCI and the management of acute coronary syndromes (ACS)[1-4]. However, since the initial introduction of TRA, a comprehensive body of evidence has accrued demonstrating the superiority of TRA with respect to vascular complications, bleeding and mortality [5-9]. Despite these data, the uptake of TRA in the United States still lags behind many other nations, particularly in the setting of ACS. Possible limitations of to the adoption of TRA in ACS, particularly in ST-segment elevation myocardial infarction (STEMI), are the beliefs that transfemoral access (TFA) is associated with faster door-to-balloon times and higher rates of procedural success. To summarize the evidence on these issues and establish an expert consensus on the role of TRA, the American Heart Association working group led by Mason et al conducted a systematic review and meta-analysis, including trials published through June 2017. This document includes 19 randomized clinical trials (RCTs) involving 21,134 patients that compare TRA versus TFA in relationship to 3 major endpoints: bleeding, vascular complications, and mortality. The pooled data demonstrate an advantage of TRA across the measured endpoints, with a greater benefit with TRA in sicker patients and those with a higher risk of bleeding. The AHA Scientific Statement by Mason et al then goes on to articulate a clear set of recommendations and best practices to guide the transition to a radial first strategy in line with current evidence

Observational studies and RCTs have shown that TRA reduces bleeding and vascular complications compared with TFA [5-18]. While the main driver for the reduction in bleeding in some trials was a reduced rate of minor or access site bleeding, other data show that both minor and major bleeding are associated with increased mortality [5, 8, 19, 20]. In the meta-analysis by Mason et al, major bleeding rates were lower in TRA compared with TFA, both in stable ischemic heart disease and ACS. The bleeding rate for TRA was 3.4% and 5.5% for TFA in this meta-analysis, with a NNT of 47 for TRA to prevent one major bleeding event. More striking are the data for reductions in vascular access complications with TRA compared with TFA. The AHA statement shows that the rate of major vascular access complications with TRA was 2.9% versus 7.7% with TFA. This equates to NNT of 21 patients with TRA to prevent one vascular complication.

Reductions in bleeding and vascular complications with TRA are accompanied by a significant reduction in mortality in ACS patients when all the randomized trial data are pooled. Smaller individual trials were not specifically powered for mortality. For example, the STEMI-RADIAL trial enrolled 707 STEMI patients undergoing primary PCI and did not show a difference in mortality between TRA and TFA. However, the RIVAL, MATRIX, and RIFLE-STEACS trials demonstrated a mortality benefit with TRA compared with TFA in ACS, and included over 16,000 patients. The meta-analysis by Mason et al shows that mortality was not different between TRA and TFA when patients with both stable ischemic heart disease and ACS were combined. However, when focused on the pooled ACS patient population alone, mortality was significantly lower in patients assigned to TRA.

A common argument against the routine use of TRA for primary PCI is that radial access and transradial PCI take longer than transfemoral PCI, potentially prolonging door-to-balloon time. While this may be true for novice TRA operators, the available data show there is no significant difference between door-to-balloon times, nor a difference in procedural success between TRA and TFA in the setting of ACS [5-7, 11, 21, 22], with the caveat that the operators included in these studies were likely very experienced with TRA. An observational study from the ACC-NCDR registry study showed that TRA was associated with a four minute mean increase in procedure time compared with TFA in STEMI cases, but clinical outcomes still favored radial access [23]. Additionally, a decision analytic modeling study using pooled mortality data from the RIVAL and RIFLE-STEACS trials showed that a substantial delay in reperfusion times, between 20-80 minutes beyond the 90 minute benchmark, was required to offset the mortality benefit of TRA access in PCI [24].

The economic impact of arterial access sites in coronary angiography and PCI is a topic of ongoing research. Current data suggests a cost savings associated with TRA compared to TFA, driven by reductions in bleeding and vascular complications, and the resultant decrease in length of ICU and hospital stays. The cost reductions afforded by TRA become more apparent in higher bleeding risk patients, such as patients with ACS and particularly patients with STEMI.

Given the data favoring TRA, Mason et al sketch out a set of best practice recommendations in TRA for treatment of ACS. One important point outlined in the document is that operators and cath lab teams should become proficient in TRA in non-emergent cases prior to deploying a radial first strategy in ACS. Requisite case volumes to achieve and maintain proficiency have been suggested to overcome the learning curve associated with TRA PCI. Approximately 30-50 cases are needed to overcome this learning curve and see reductions in contrast use and radiation exposure [25]. Importantly, mortality, bleeding and vascular complications remain low across TRA volumes, suggesting patient safety is not compromised during this period [25]. Additionally, the relationship between case volume and procedural success does not appear to have a threshold [25, 26]. Other important concepts addressed in the document include the role of collateral testing of hand circulation to triage for radial artery access, use of ultrasound guidance, and maintaining proficiency in femoral artery access. The RADAR study has demonstrated that conventional wisdom surrounding collateral circulation is not accurate in predicting TRA safety [27]. Additionally, use of ultrasound in access increases procedural success. Transitioning to a radial first strategy should not limit centers or operators understanding and maintenance of femoral artery access techniques and best practices as TFA is employed in many other procedures such as percutaneous ventricular assist devices, structural heart cases, and peripheral vascular interventions.

The current AHA Scientific Statement provides an important summary of the data on TRA, particularly in the setting of ACS. The available data support the role of TRA as the preferred route of access in ACS patients due to its superior safety profile. Not only does TRA PCI reduce major bleeding events and vascular access site complications, it also has a mortality benefit in ACS. In addition to its favorable patient outcomes, data suggest it is preferred by patients and leads to reductions in costs to the healthcare system. As such, the data support the conclusion by Mason et al that a shift to a radial first strategy in ACS is recommended. The AHA Scientific Statement goes on to establish recommendations for the application of TRA, giving welcome guidance to physicians and health systems seeking to implement best practices in TRA.