Transient atrial fibrillation complicating acute inferior myocardial infarction: implications for future risk of ischemic stroke.

BACKGROUND: Atrial fibrillation (AF) that occurs as a frequent complication of myocardial infarction (MI) is associated with a poor clinical outcome. It nonetheless remains uncertain whether AF that occurs transiently during MI is associated with a subsequent increased risk of the development of AF and ischemic stroke.
METHODS: We retrospectively studied the impact of transient AF on the long-term risk of the occurrence of AF, ischemic stroke, and mortality in 431 consecutive patients (mean [+/- SEM] age, 64 +/- 1 years; 75% men). All patients had experienced an acute inferior ST-segment-elevation MI and had preserved left ventricular ejection fraction (LVEF) [> 45%].
RESULTS: All patients were in sinus rhythm on hospital admission, and transient AF was observed in 59 patients (13.7%) during their hospitalization for MI. On hospital discharge, all patients were in sinus rhythm and had been prescribed antiplatelet agents alone as antithrombotic therapy. Patients in whom transient AF developed during MI were older (mean age, 70 +/- 1.4 vs 64 +/- 0.7 years, respectively; p < 0.01) and more likely to be women (37% vs 23%, respectively; p < 0.02) compared with those without AF. At 1-year follow-up, the incidence of AF (22.0% vs 1.3%, respectively; p < 0.01) and ischemic stroke (10.2% vs 1.8%, respectively; p < 0.01) was higher in patients with transient AF than in those without transient AF. The total mortality rate was nonetheless similar (5.6% vs 6.8%, respectively; p = 0.73); Cox regression analysis demonstrated that age > 65 years and transient AF during MI were independent predictors of the subsequent occurrence of AF and the development of ischemic stroke.
CONCLUSION: Transient AF complicating acute inferior MI is associated with an increased future risk of AF occurrence and ischemic stroke in patients with preserved LVEF, despite the use of antiplatelet therapy.