Subclinical atrial fibrillation: Who benefits from oral anticoagulation?

Abstract

The value of anticoagulation to prevent embolic strokes in subclinical atrial fibrillation detected by implantable cardiac devices has not been established. Recently, two randomized controlled studies scrutinized whether such patients benefit from oral anticoagulation to prevent embolic strokes. These two studies were the NOAH-AFNET-6 (Anticoagulation with Edoxaban in patients with atrial high-rate episodes) trial and the ARTESIA (Apixaban for stroke prevention in subclinical atrial fibrillation) study but separately came to different conclusions using different primary endpoints. While the investigators of NOAH-AFNET-6, based on a composite primary endpoint, concluded that no patient with device-detected AF should be anticoagulated, the ARTESIA investigators demonstrated overall value of anticoagulation based on stroke/systemic embolism as sole endpoint. However, the main question for subclinical atrial fibrillation patients is to which extent stroke and thromboembolism can be prevented by anticoagulation and weighing such a benefit to the risk of major bleeding. After initial confusion a meta-analysis of both studies focusing on the endpoint "ischemic stroke" and "all-cause stroke" revealed an overall superiority of anticoagulation against placebo/aspirin therapy. The combined evidence did in the end inform the cardiovascular community of the superiority of anticoagulation but confined to those with high risk i.e. CHA₂DS₂-VASc score >4, particularly in those with any type of vascular disease. The meta-analysis also revealed that no anticoagulation is indicated in patients with CHA₂DS₂-VASc score <4, and with shared decision making recommended for those with CHA₂DS₂-VASc score of = 4. It is reassuring that despite a first impression of diverging results of the major two trials, a meta-analysis helped to clarify the uniformity and consistency of the results across the studies, which will help physicians and nurses in their daily care of patients with implantable devices.