An algorithm for the quantification of ST-T segment variability

A template boundary algorithm which quantitatively determines repolarization (ST-T segment) variability in a normal population has been developed. The algorithm defines an initial ST-T template for comparison with successive beats. Variability is quantified using boundary limits around the template which are widened, when necessary, to included incoming ST-T segments. The boundaries at the end of each hour are stored and the collection of boundaries over a set of normal subjects quantifies the normal variation over the entire ST-T segment. The algorithm can be used to determine prospectively normal ST-T variability based on a regression analysis of R-wave or T-wave amplitude, and QT interval. Application of these boundary predictions should be useful in distinguishing repolarization changes secondary to ischemia from normal variability.