Anticoagulation appeared to be beneficial in a subgroup with past strokes or transient ischaemic attacks.

In the international ARTESiA trial, 4000 patients with CHA₂DS₂-VASc scores of three or higher and episodes of subclinical atrial fibrillation (AF; detected by implanted pacemaker, defibrillator or cardiac monitor, and lasting six minutes or longer but less than 24 hours) were randomised to apixaban or aspirin. Apixaban recipients had fewer strokes and more major bleeding events than did aspirin recipients, but the absolute difference for both outcomes was less than one per 100 patient-years. With these low event rates, there was no decisive advantage for anticoagulation (NEJM JW Gen Med Dec 15 2023 and N Engl J Med 2024; 390: 107-117).

Now, in a secondary analysis, the researchers have examined outcomes in an important subgroup – the 9% of participants who had previous strokes or transient ischaemic attacks (TIAs) before enrolment in the trial; most of those prior strokes and TIAs occurred longer than one year prior to enrolment. During mean follow up of 3.5 years, outcomes in this subgroup were as follows:

• incidence of stroke or systemic embolism was about seven percentage points lower with apixaban than with aspirin
• incidence of major bleeding was about three percentage points higher with apixaban than with aspirin.

Comment: In this subgroup of patients with histories of stroke or TIA and later detection of subclinical AF, the potential benefit of anticoagulation appeared to outweigh the potential harm. This report does not provide information on the presumed causes of the previous strokes, but one might expect that many were embolic strokes of undetermined source.

Allan S. Brett, MD, Clinical Professor of Medicine, University of Colorado School of Medicine, Aurora, USA.

Shoamanesh A, et al. Apixaban versus aspirin for stroke prevention in people with subclinical atrial fibrillation and a history of stroke or transient ischaemic attack: subgroup analysis of the ARTESiA randomised controlled trial. Lancet Neurol 2025; 24: 140-151.

This summary is taken from the following Journal Watch titles: General Medicine, Ambulatory Medicine, Hospital Medicine, Neurology.