Cardiac care unit admission criteria for suspected acute myocardial infarction in new-onset atrial fibrillation.

Management of new-onset atrial fibrillation (AF) varies between institutions and individual physicians. Because AF often occurs in elderly patients and is associated with coronary artery disease, patients presenting for the first time are often selected for admission to the coronary care unit to exclude the possibility of acute myocardial infarction (AMI). A review of 245 patients with AF admitted to an intensive care unit revealed 45 cases that were of new onset. AMI was diagnosed in 5 (11%) on the basis of elevated serum creatine kinase-MB levels. Evaluation of 56 clinical variables available during initial assessment indicated that infarction patients could be distinguished from others by the presence of left ventricular hypertrophy (p less than 0.01), electrocardiographic evidence of old myocardial infarction (p less than 0.01), typical cardiac chest pain (p less than 0.01), and duration of cardiac symptoms less than 4 hours (p less than 0.05). The presence of 2 or more of these features identified all AMI patients and 7 others at high risk for serious cardiac complications. The findings indicate that new-onset AF in the absence of clinical predictors suggesting myocardial ischemia or AMI does not warrant routine admission to the coronary care unit.