Atrial fibrillation in acute myocardial infarction: a prospective study based on data from a consecutive series of patients admitted to the coronary care unit.

Atrial fibrillation (AF) is a common and much-studied arrhythmia in patients with acute myocardial infarction (MI). However, documentation of its occurrence in temporal association with MI has been often neglected in the literature; also, its frequent occurrence with mere advanced age, or in the setting of various cardiac conditions or complications, has prevented the definition of an exact role for AF as a marker or determinant of outcome in patients with MI. The purpose of this study was to evaluate prospectively the frequency of AF (present or occurring subsequently) in a consecutive series of patients with MI admitted to the Coronary Care Unit, and to explore for variables associated with this arrhythmia; the role of AF in determining major clinical outcomes of the patients was also examined. A large data base of baseline, clinical, laboratory, and patient outcome variables was generated and continuously updated to examine correlates of AF and its possible role in determining prognosis. AF was found in 72 of 517 patients, of whom 58 experienced this arrhythmia anew. Univariate analyses detected a positive association of AF with age, pulmonary congestion, left ventricular hypertrophy, high admission Killip class, and a large array of complications including in-hospital mortality. Multivariate analyses showed, however, that AF correlated weakly with age and strongly with left ventricular hypertrophy and occurrence of ventricular tachycardia, but that it was not a determinant of ventricular fibrillation or in-hospital mortality.