The clinical course of 'Takotsubo' cardiomyopathy closely resembles that of acute myocardial infarction (AMI) and coronary angiography (CAG) is usually performed to distinguish the 2 conditions during the acute phase. The present study was designed to determine whether the standard 12-lead electrocardiogram (ECG) findings could help to distinguish 'Takotsubo' cardiomyopathy from anterior AMI. The study group comprised 13 patients with 'Takotsubo' cardiomyopathy and 13 consecutive patients with anterior AMI. Patients with 'Takotsubo' cardiomyopathy had abnormal Q waves less frequently than patients with anterior AMI (15% vs 69%, p=0.008). No reciprocal changes were seen in the inferior leads in patients with 'Takotsubo' cardiomyopathy (p=0.0003). The ratio of ST-segment elevation in leads V(4-6) to V(1-3) (SigmaSTeV(4-6)/V(1-3)) was significantly higher in patients with 'Takotsubo' cardiomyopathy (1.55+/-0.53 vs 0.57+/-0.58, p=0.0004). The QTc interval was significantly longer in patients with 'Takotsubo' cardiomyopathy. The absence of reciprocal changes, absence of abnormal Q waves, and a SigmaSTeV(4-6)/V(1-3) >/=1 all showed a high sensitivity and specificity for diagnosing 'Takotsubo' cardiomyopathy. Furthermore, the combination of the absence of reciprocal changes and a SigmaSTeV(4-6)/V (1-3) >/=1 had a greater specificity (100%) and overall accuracy (91%) than either criteria. Therefore, the standard 12-lead ECG on admission can help to distinguish 'Takotsubo' cardiomyopathy from anterior AMI.