The ST Compass: spatial visualization of ST-segment deviations and estimation of the ST injury vector

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.