The OAC-ALONE trial presented Sept. 24 at TCT 2018 and simultaneously published in Circulation attempted to be the first randomized controlled trial evaluating oral anticoagulation (OAC) alone without antiplatelet therapy (APT) in patients with atrial fibrillation (AFib) and stable coronary artery disease (CAD) beyond one year after coronary stenting. Unfortunately, the trial was terminated due to low patient enrollment, leaving the jury still out on the optimal antithrombotic regimen for this patient group, despite some guideline recommendations for OAC alone.

The prospective, multicenter, open-label, non-inferiority trial aimed to randomize 2,000 patients over 12 months to either OAC alone or combined OAC and single APT. The primary endpoint was a composite of all-cause death, myocardial infarction (MI), stroke or systemic embolism. The secondary endpoint was a composite of primary endpoint or major bleeding according to the International Society on Thrombosis and Haemostasis classification. The study was prematurely terminated after only enrolling 696 patients in 38 months.

While non-inferiority of OAC alone compared with combined OAC and APT was not established, of those patients enrolled the primary endpoint occurred in 54 patients (15.7 percent) in the OAC alone group and in 47 patients (13.6 percent) in the combined OAC and APT group. The major secondary endpoint occurred in 67 patients (19.5 percent) in the OAC alone group and in 67 patients (19.4 percent) in the combined OAC and APT group. Broken down by event, MI occurred in eight patients in the OAC group, compared with four patients in the OAC and APT group, while stroke or systemic embolism occurred in 13 patients in the OAC group and 19 patients in the OAC and APT group. Major bleeding was higher in the OAC and APT group (36 patients) compared with the OAC group (27 patients).

"Because patient enrollment was prematurely terminated, the study was underpowered and inconclusive," the authors said. "Future larger studies are required to establish the optimal antithrombotic regimen in this population."

In a related editorial comment, Gilles Lemesle, MD, PhD, writes that despite the "tantalizing observations" from OAC-ALONE, the issue of which strategy should be considered as default in clinical practice (and for which patients)" is still not settled. However, she notes the findings "will be useful in planning future trials."

Keywords: TCT18, Transcatheter Cardiovascular Therapeutics, Angiography, Percutaneous Coronary Intervention, Drug-Eluting Stents, Atrial Fibrillation, Blood Coagulation

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