The current electrocardiogram criteria for the diagnosis of transmural myocardial ischemia focus on ST elevations, although anterior lead ST depression may be indicative of posterior ischemia. ST elevation and depression in different leads may be considered different projections of a common ST injury current directed toward areas of transmural ischemia. To facilitate vectorial analysis of ST deviations, we present the ST Compass—a new tool for visualization of ST deviations from standard 12-lead electrocardiograms. We also present a method to estimate a vector describing the magnitude and direction of the underlying ST injury current based on the observed ST deviations. In 2 cases of acute myocardial infarction, the ST deviation vectors form a clear pattern in the ST Compass, and the spatial direction of the ST injury current corresponds to the location of myocardial ischemia as confirmed by single-photon emission computed tomography imaging.

Introduction Morphological differences in the T-wave appearance have been qualitatively described in the Long QT syndrome (LQTS). T-wave morphology has been used to separate LQTS types from each ot...

QTc prolongation due to the administration of a drug is not a reliable surrogate of the drug’s proarrhythmic potential. Consequently, the development of suitable indices for the characterization of drug-induced repolarization changes might greatly improve risk assessment of new and existing compounds. This study adds a T-wave morphology composite score (MCS) to the QTc interval evaluation of drugs affecting cardiac repolarization. Electrocardiographic recordings from 62 subjects on placebo and 400 mg moxifloxacin were compared to recordings from 21 subjects receiving 160 and 320 mg d,l-sotalol. The antibiotic drug, moxifloxacin has a favorable cardiovascular safety profile and is recommended as a positive control in thorough QT studies. In contrast, the antiarrhythmic drug d,l-sotalol has a less favorable safety profile with a reported incidence of TdP between 1.8% and 4.8%. This difference in risk profiles between moxifloxacin and d,l-sotalol is indicated by T-wave morphology changes, as assessed by ΔMCS. T-wave morphology changes are larger for 320 mg d,l-sotalol than for 160 mg d,l-sotalol, which are again larger than for moxifloxacin and placebo. Covariate analyses of ΔQTc and ΔMCS showed T-wave morphology changes as a significant effect of dl-sotalol. In contrast, there is no effect of moxifloxacin on T-wave morphology (ΔMCS) at any given change in QTc. This study offers new insights into the repolarization behavior of a drug with low cardiac risk versus a high risk drug and suggests