Electrocardiogram mimics of acute ST-segment elevation myocardial infarction: insights from cardiac magnetic resonance imaging in patients with tako-tsubo (stress) cardiomyopathy.

An important subset of patients (approximately 10%) with chest pain and ST-segment elevation on initial electrocardiogram (ECG) do not have acute coronary occlusion. In our experience, 5% of women presenting with chest pain and ST-segment elevation are proven to have the newly recognized syndrome of tako-tsubo (stress) cardiomyopathy (TC). Patients with TC present with clinical and electrocardiographic features mimicking ST-segment elevation anterior myocardial infarction due to left anterior descending (LAD) occlusion. The initial and subsequent ECG findings in TC are therefore of clinical importance. Thirty-three consecutive patients with TC were identified from within a single institution community-based cardiology practice. All were female aged 32 to 90 years (mean, 68 years) with acute chest pain associated with an emotional or physical stressful event, and akinesia of the mid-distal left ventricle but without significant atherosclerotic coronary artery obstruction. All patients with TC presented with anterior ST-segment elevation most marked in leads V(1) to V(5), maximal in leads V(2) and V(3). Distribution of ST-segment elevation was similar to 44 female control patients with acute (LAD) occlusion. ST-segment elevation magnitude was less in patients with TC (1.4 +/- 1.5 mm) than in patients with LAD occlusion (2.4 +/- 2.2 mm) (P < .001) but with considerable overlap. Left ventricular ejection fraction (LVEF) was significantly lower in TC patients (29% +/- 9%) than in patients with LAD occlusion (42% +/- 13%) (P < .05). Peak troponin T was significantly lower in patients with TC (0.64 +/- 0.86 ng/mL) than in patients with LAD occlusion (3.88 +/- 4.9 ng/mL) (P < .0001). Cardiovascular magnetic resonance imaging detected myocardial necrosis in 1 patient with TC. At follow-up, LVEF returned to normal (> 50%) in all patients with TC. In patients with TC, ECG evolution was characterized by resolution of ST-segment elevation, appearance of T-wave inversion (most marked in precordial leads V(3)-V(6) and limb leads aVL, I, and -aVR), QTc interval prolongation (378 +/- 60 milliseconds [initial] vs 470 +/- 72 milliseconds [follow-up], P < .05), and reappearance of precordial R waves. In conclusion, patients with TC frequently present with anterior ST-segment elevation, which cannot be reliably distinguished from that of acute LAD occlusion. In TC, the combination of minimal troponin release, absent delayed hyperenhancement on cardiac magnetic resonance imaging (in most of patients), and return to normal LVEF is consistent with the presence of significant myocardial stunning. The ECG evolution of progressive T-wave inversion, QTc interval lengthening, and R-wave reappearance could be the electrophysiologic manifestation of an underlying stunned myocardium in this condition.