Electrocardiographic differentiation of atrial flutter from atrial fibrillation by physicians.

The purpose of this study was to determine the ability of physicians to differentiate atrial flutter from atrial fibrillation on a surface electrocardiogram (ECG). A questionnaire containing three 12-lead ECGs was mailed to 689 physicians, with multiple-choice questions asking whether the rhythm on each ECG was atrial flutter or atrial fibrillation. ECG 1 showed atrial fibrillation with prominent atrial activity (>0.2 mV) in lead V1; ECG 2 displayed atrial fibrillation with prominent atrial activity (>0.2 mV) in leads III and V1; and ECG 3 displayed atrial flutter. Overall, ECG1 was correctly identified as atrial fibrillation by 79% of physicians, ECG 2 was correctly identified as atrial fibrillation by 31%, and ECG 3 was correctly identified as atrial flutter by 90%. Cardiology fellows and cardiologists correctly identified ECG 1 more often than house officers and internists (95% vs 63%; P < or = .01). ECG 2 was correctly identified by 26% of cardiology fellows and cardiologists and by 37% of house officers and internists (P = .10). ECG 3 was correctly identified by 91% of cardiology fellows and cardiologists and by 82% of house officers and internists (P = .06). In conclusion, atrial fibrillation is frequently misdiagnosed as atrial flutter. Misdiagnosis of atrial fibrillation occurs more often when atrial activity is prominent on an ECG in more than one lead.