A large, randomized multicenter trial has shown that radial access for coronary angiography with possible percutaneous coronary intervention (PCI) is not superior to femoral access. In secondary and exploratory analyses, the study observed that radial access was associated with a reduction in major vascular access site complications, was superior for the primary outcome when performed at high-volume radial centers, and was associated with better outcomes for patients with ST-segment elevation myocardial infarction (STEMI). Sanjit S. Jolly, MD, McMaster University, Hamilton, Ontario, Canada, presented the findings of the study.

The Radial versus Femoral Access for Coronary Intervention (RIVAL; NCT01014273) trial was designed to provide randomized controlled trial data to test the hypothesis that radial access is superior to femoral access in patients with acute coronary syndrome (ACS) who are undergoing PCI. This hypothesis was generated by a meta-analysis that showed a significant reduction in bleeding events with radial access, with a trend toward fewer ischemic events, among patients with ACS [Jolly SS. Am Heart J 2009].

The RIVAL trial first enrolled patients as part of the ACS trial CURRENT-OASIS 7 [CURRENT–OASIS 7 Investigators. N Engl J Med 2010]. Patients were included in RIVAL if an invasive approach was planned and if the interventional cardiologist was willing to proceed with either radial or femoral access and had expertise for both (at least 50 radial procedures for coronary angiography or intervention within the previous year). The original sample size of 4000 was increased to 7000 by the RIVAL steering committee during the trial due to a lower-than-expected overall event rate for the primary outcome and because a sample size of 7000 would provide 80% power to detect a 25% relative risk reduction with a control event rate of 6% and a 30% relative risk reduction with a control event rate of 4% to 5%.

RIVAL enrolled 7021 patients at 158 hospitals in 32 countries. The patients were randomly assigned to radial access (n=3507) or femoral access (n=3514). The primary outcome was a composite of death, myocardial infarction (MI), stroke, or noncoronary artery bypass graft (non-CABG)-related major bleeding at 30 days. Secondary outcomes included death, MI, or stroke at 30 days; non-CABG-related major bleeding at 30 days; and major vascular access site complications.

There were no significant differences between the two groups with respect to either the primary or secondary outcomes that were related to death, MI, stroke, or non-CABG-related bleeding. The primary outcome occurred in 3.7% of the patients in the radial group and 4.0% of the patients in the femoral group (HR, 0.92; 95% CI, 0.72 to 1.17; p=0.50). There was, however, a difference in the rate of major vascular site complications, with fewer complications that were associated with radial access (1.4% vs 3.7%; HR, 0.37; 95% CI, 0.27 to 0.52; p < 0.0001).

The researchers compared the two approaches in six prespecified subgroups: age (< 75 and ≥75 years), gender, body mass index, PCI volume by operator, radial access volume by center, and diagnosis at presentation (non-STEMI and STEMI). The results were similar in all subgroups with two exceptions: a significant difference was observed in favor of radial access when performed at centers with the highest volume of radial access procedures (HR, 0.49; 95% CI, 0.28 to 0.87; p=0.015) and in patients with STEMI (HR, 0.60; 95% CI, 0.38 to 0.94; p=0.026).

Overall, RIVAL showed no significant benefit for radial access compared with femoral access in patients who presented with ACS. Reasons for this neutral result may include inadequate power to detect a difference of the magnitude that was observed. In the associated manuscript, the authors state, “RIVAL was underpowered to conclusively rule out moderate but important differences in the primary outcome. On the basis of the reported event rate of 4%, a sample of size of 17,000 patients would be needed to have 80% power to detect a 20% relative risk reduction in the primary outcome.” Although the findings are neutral overall, clinicians may find the observations that radial access was associated with reduced rates of major vascular complications compared with femoral access and that the effectiveness of radial access appeared to be associated with expertise and volume to be helpful in clinical decision-making.

Further Reading: Jolly SS et al. Lancet 2011.