T‐Wave Abnormality as Electrocardiographic Signature of Myocardial Edema in Non‐ST‐Elevation Acute Coronary Syndromes

BACKGROUND T-wave abnormalities are common during the acute phase of non-ST-segment elevation acute coronary syndromes, but mechanisms underlying their occurrence are unclear. We hypothesized that T-wave abnormalities in the presentation of non-ST-segment elevation acute coronary syndromes correspond to the presence of myocardial edema. METHODS AND RESULTS Secondary analysis of a previously enrolled prospective cohort of patients presenting with non-ST-segment elevation acute coronary syndromes was conducted. Twelve-lead electrocardiography (ECG) and cardiac magnetic resonance with T2-weighted imaging were acquired before invasive coronary angiography. ECGs were classified dichotomously (ie, ischemic versus normal/nonischemic) and nominally according to patterns of presentation: no ST- or T-wave abnormalities, isolated T-wave abnormality, isolated ST depression, ST depression+T-wave abnormality. Myocardial edema was determined by expert review of T2-weighted images. Of 86 subjects (65% male, 59.4 years), 36 showed normal/nonischemic ECG, 25 isolated T-wave abnormalities, 11 isolated ST depression, and 14 ST depression+T-wave abnormality. Of 30 edema-negative subjects, 24 (80%) had normal/nonischemic ECGs. Isolated T-wave abnormality was significantly more prevalent in edema-positive versus edema-negative subjects (41.1% versus 6.7%, P=0.001). By multivariate analysis, an ischemic ECG showed a strong association with myocardial edema (odds ratio 12.23, 95% confidence interval 3.65-40.94, P<0.0001). Among individual ECG profiles, isolated T-wave abnormality was the single strongest predictor of myocardial edema (odds ratio 23.84, 95% confidence interval 4.30-132, P<0.0001). Isolated T-wave abnormality was highly specific (93%) but insensitive (43%) for detecting myocardial edema. CONCLUSIONS T-wave abnormalities in the setting of non-ST-segment elevation acute coronary syndromes are related to the presence of myocardial edema. High specificity of this ECG alteration identifies a change in ischemic myocardium associated with worse outcomes that is potentially reversible.