Stroke prevention in atrial fibrillation: evidence from real-life studies

Atrial fibrillation (AF) is an increasing public health issue, especially owing to an accompanying five-fold increased risk of stroke. Anticoagulants are the cornerstone of therapy for stroke prevention in AF. The clinical benefits of vitamin K antagonists (VKAs; namely warfarin) shown in randomized controlled trials (RCTs) have been challenged when used in clinical practice by issues including the need for international normalized ratio (INR) monitoring, food and drug interactions, low time in the therapeutic range in substantial numbers of patients, and serious bleeding events. Combined, these have led to both an under-initiation of VKAs and high rates of VKA discontinuation. Non-VKA oral anticoagulants (NOACs), including the oral, direct factor Xa inhibitors apixaban and rivaroxaban and the oral, direct thrombin inhibitor dabigatran, are transforming the anticoagulation landscape. These agents have shown favourable outcomes in Phase III RCTs and are licensed for the use in Europe and many other regions around the world for stroke prevention in AF. However, the safety and effectiveness of NOACs in real-world patients with AF outside RCTs is not well understood. Non-interventional studies and registries are becoming ever more important in understanding the real-life benefit-risk profile of NOACs. This review will evaluate questions that remain unanswered despite the wealth of RCT data available, and will describe a number of pivotal real-life studies that have been completed or are ongoing in the area of stroke prevention in AF, in an effort to extend our understanding of NOAC use to routine clinical practice and optimise patient care.