Radial vs Femoral Arterial Access for Coronary Angiography and Intervention in Acute Coronary Syndromes
Abstract & Commentary
By Andrew J. Boyle, MBBS, PhD, Assistant Professor of Medicine, Interventional Cardiology, University of California, San Francisco.
Source: Jolly SS, et al. Radial versus femoral access for coronary angiography and intervention in patients with acute coronary syndromes (RIVAL): A randomised, parallel group, multicentre trial. Lancet 2011;377:1409-1420.
Several studies have shown lower rates of arterial access site complications when performing cardiac catheterization via the radial artery compared to the femoral artery, but these have largely been retrospective studies or registries. Jolly and colleagues performed a prospective randomized trial of radial vs femoral access for patients undergoing cardiac catheterization during hospitalization for acute coronary syndromes (ACS). In this large study, more than 7000 patients were enrolled. Initially, this study began as an investigator-initiated substudy within the OASIS-7 trial, which compared high and low doses of aspirin and clopidogrel, but after that study ended they continued the RIVAL trial as a stand-alone clinical trial. The primary endpoint was a composite of death, myocardial infarction (MI), stroke, and non-coronary artery bypass graft (CABG) major bleeding.
Patients presenting with ACS, including unstable angina (UA), non-ST-elevation MI (NSTEMI), and ST-elevation MI (STEMI), who were scheduled to undergo invasive management, were randomized to radial (n = 3507) or femoral (n = 3514) arterial access. The study was performed at high volume radial centers and involved operators facile with either femoral or radial access (≥ 50 radial procedures in the preceding year). There were no differences in the baseline demographics between groups: approximately 74% were male, mean age was 62 ± 12 years, 21% were diabetic, 45% presented with UA, 27% had non-STEMI, and 28% had STEMI.
Of the 7021 who underwent coronary angiography, 66.4% had percutaneous coronary intervention (PCI), 8.5% had CABG, and the remainder received medical therapy alone. Smaller sheath sizes were used more often in the radial cases, but PCI success was 95% in each group. Access site crossover occurred more frequently in the radial group (7.6% vs 2.0%; P < 0.0001). Based on intention-to-treat analysis, the rate of occurrence of the primary endpoint did not differ between groups (3.7% vs 4.0%; P = 0.50); nor did the rate of the individual components of the primary endpoint (death 1.3% vs 1.5%; MI 1.7% vs 1.9%, stroke 0.6% vs 0.4%, non-CABG major bleeding 0.7% vs 0.9% in the radial and femoral groups, respectively). Radial access was associated with a lower rate of major vascular complications (1.4% vs 3.7%; P < 0.0001).
The authors performed subgroup analyses to determine whether patients presenting with STEMI had different outcomes. In those presenting with STEMI, the primary endpoint favored radial access (3.1% vs 5.2%; P = 0.026), as did the rate of death (2.7% vs 4.6%; P < 0.01). In patients at the highest volume radial centers, there also was a significantly better primary outcome (1.6% vs 3.2%; P = 0.015). In all subgroup analyses, the rate of vascular access complications favored radial and the rate of access site crossover favored femoral. The authors conclude that both radial and femoral approaches are safe and effective for PCI. However, the lower rate of local vascular complications may be a reason to use the radial approach.
The RIVAL trial showed no difference between radial and femoral access in the composite primary endpoint of death, MI, stroke, and major non-CABG bleeding, but radial access was associated with a lower rate of vascular access complications. It seems intuitive that the site of access would have little effect on death, stroke, and MI in patients experiencing ACS. But why was there no significant improvement in bleeding outcomes? The authors offer several explanations. First, the rate of major bleeding in the femoral group was unexpectedly low (0.9%), much lower than other contemporary PCI trials in this patient population, so that made it difficult to show a difference between groups. It is important to note that in the RIVAL trial two-thirds of bleeding events occurred remotely from the access site. So the site of access is not likely to make much difference to bleeding outcomes. Second, their definition of major bleeding was very strict and did not include vascular access complications and major hematomas. In fact, they performed an exploratory analysis using a definition of bleeding that included hematoma and vascular access site complications requiring intervention (the ACUITY major bleeding definition) and found that radial access was associated with a lower primary outcome event rate. The authors also note that the rate of vascular closure device use was only 26% in the femoral group, and that those receiving a vascular closure device had a lower rate of bleeding.
The subgroup analyses were interesting. In the highest volume radial centers, and in patients presenting with STEMI, there was a lower incidence of the primary endpoint in the radial group. This suggests that there may be benefit to radial access in the highest bleeding risk patients (STEMI) and in high-volume centers. There is certainly a significant learning curve with using radial access, and in this trial only high-volume radial operators were involved. Even so, there were better outcomes at the highest volume centers within the study, suggesting the learning curve involves the entire institution.
This study confirms that radial and femoral arterial access are acceptable alternatives in patients presenting with ACS who are undergoing invasive treatment. Both result in equivalent efficacy outcomes, although radial access may slightly reduce access site complications. Physician preference and experience should be taken into account when deciding on the access site.