Association between atrial fibrillation and cardiac and cerebrovascular events
Several previous epidemiological studies1-3 have identified AF as a strong risk factor for cardiac/cerebrovascular events and death. In AF, a loss of effective atrial contraction, atrial dilatation, endocardial denudation, abnormal changes in blood constituents, and inflammation occur in the atrium to fulfill Virchow’s triad for thrombogenesis.15 Furthermore, loss of atrial contraction by AF reduces cardiac output by up to 25%, particularly in diastolic dysfunction.16 AF can also lead to arrhythmia-induced left ventricular dysfunction, which is induced by extracellular matrix remodeling, cellular remodeling, and defects in calcium ion handling.17 Based on these clinical and basic observations, maintenance of sinus rhythm can theoretically be expected to reduce the risk of cardiac and cerebrovascular events in patients with AF.
However, in the landmark the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial,18 a rhythm-control therapy using antiarrhythmic drugs failed to show a survival advantage over a rate-control therapy in patients with AF and a high risk for stroke or death. On the other hand, the substudy of the AFFIRM trial found that the presence of sinus rhythm was independently associated with a survival benefit, whereas AAD use was associated with increased mortality.19 These results suggest that an effective method for maintaining sinus rhythm with fewer adverse effects, such as catheter ablation, might improve survival.