The European Society of Cardiology
Recent trials in atrial fibrillation: lessons learned beyond rate and rhythm
Department of Internal Medicine III (Cardiology), University of Freiburg, Hugstetter Str. 55, Freiburg, Germany
* Christoph Bode, Department of Internal Medicine III (Cardiology), University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany. Tel.: +49-761/270-3441; fax: +49-761/270-3200
bode{at}mm31.ukl.uni-freiburg.de
Abstract
Atrial fibrillation (AF) is a common disorder, responsible for the majority of hospitalizations due to arrhythmias. It is well established that AF predisposes patients to the development of thrombi and a markedly increased risk of ischaemic stroke. The prevalence of AF increases dramatically with age, and, as the overall population ages, AF will become an increasingly important cause of morbidity and mortality. Numerous prospective randomized studies have shown that oral anticoagulation is an effective means for primary stroke prevention (risk reduction [RR] 62%) as well as secondary RR. Aspirin is also effective but to a lesser degree than oral anticoagulation. In a meta-analysis of six clinical trials, aspirin reduced the risk of stroke by approximately 20%. The risk reduction with aspirin just achieved statistical significance and there was considerable variability in the effects of aspirin in the individual trials, with only one of the six trials demonstrating a statistically significant reduction in the risk of stroke with aspirin. The balance between efficacy for stroke prevention and safety with regards to bleeding complications is best achieved at a target international normalized ratio of 2.0–3.0. This has been confirmed by several prospective studies and retrospective analyses. Trials evaluating rate control versus rhythm control strategies in AF have reinforced the need for continued anticoagulation. The AFFIRM (Atrial Fibrillation Follow-up of Rhythm Control Management) and RACE (Rate Control Versus Electrical Cardioversion) trials have demonstrated a high rate of stroke even in ‘rhythm-controlled’ patients and have given the medical community reason to reconsider the cessation of anticoagulation in cardioverted patients. However, ultimately, the fear of bleeding complications, specifically intracranial haemorrhage, has resulted in the underuse of anticoagulation despite its proven efficacy. The recent American College of Cardiology/American Heart Association/European Society of Cardiology guidelines for the management of AF recommend an individualized approach based on the estimated risk for stroke and bleeding during anticoagulation. Newer agents with more predictable anticoagulation, and thus expected improvement of the risk/benefit ratio, may not only help clinicians meet the guideline recommendations but also expand the number of patients eligible for highly effective stroke-preventive treatment.
Key Words: Stroke prevention • Oral vitamin K antagonists • Non-valvular atrial fibrillation • Aspirin • Anticoagulation • Haemorrhagic stroke