OAC-ALONE Studies Antithrombotic Therapy Beyond 1-Year for Stent Patients With Atrial Fibrillation
September 24, 2018—The Cardiovascular Research Foundation (CRF) announced that findings from the first randomized trial of its kind was unable to establish noninferiority of oral anticoagulation (OAC) alone to combined OAC and a single antiplatelet agent (APT) in patients with atrial fibrillation (AF) and stable coronary artery disease beyond 1 year after stent implantation.
The findings of the OAC-ALONE study were reported at TCT 2018, the 30th annual Transcatheter Cardiovascular Therapeutics scientific symposium, which is sponsored by CRF and held September 21–25 in San Diego, California. The study was also published simultaneously in Yukiko Matsumura-Nakano, MD, et al in Circulation.
Dr. Nakano, who is with the Kyoto University Graduate School of Medicine in Kyoto, Japan, commented in the CRF press release, “In patients with concomitant atrial fibrillation and stable coronary artery disease beyond 1 year after coronary stent implantation, the ESC guidelines have consistently recommended oral anticoagulation without antiplatelet therapy. In clinical practice, however, antiplatelet therapy is often used on top of oral anticoagulation beyond 1 year after coronary stenting. Importantly, no randomized controlled trials have evaluated OAC monotherapy in this patient subset.”
The trial was designed to enroll 2,000 patients for 12 months. However, enrollment was prematurely terminated after enrolling 696 patients in 38 months. Dr. Nakano advised, “Because the patient enrollment was prematurely terminated, the study was underpowered and inconclusive. Larger adequately powered randomized trials are required to establish the optimal antithrombotic regimen in this population.”
As summarized by CRF, the 696 patients were enrolled at 111 participating centers from November 2013 to December 2016. Patients were randomized 1:1 to OAC alone (n = 344) or combined OAC and APT (n = 346). The patients' mean age was 75.0 ± 7.6 years, and 85.2% were men. OAC was warfarin in 75.2% and direct oral anticoagulants in 24.8% of patients. The baseline clinical characteristics were similar in both groups.
The primary endpoint was a composite of all-cause death, myocardial infarction (MI), stroke, or systemic embolism, while the major secondary endpoint was a composite of the primary endpoint or major bleeding according to the International Society on Thrombosis and Hemostasis classification.
The investigators found that during a median follow-up interval of 2.5 years, the primary endpoint occurred in 54 patients (15.7%) in the OAC alone group and in 47 patients (13.6%) in the combined OAC and APT group (hazard ratio [HR], 1.16; 95% confidence interval [CI], 0.79 to 1.72; Pnoninferiority = .2; Psuperiority = .45).
The major secondary endpoint occurred in 67 patients (19.5%) in the OAC alone group and in 67 patients (19.4%) in the combined OAC and APT group (HR, 0.99; 95% CI, 0.71 to 1.39; Pnoninferiority = .016; Psuperiority = .96). MI occurred in eight (2.3%) and four (1.2%) patients; stroke or systemic embolism occurred in 13 (3.8%) and 19 (5.5%) patients; and major bleeding occurred in 27 (7.8%) and 36 (10.4%) patients, reported the CRF in its press release.