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.