Semi-automatic method quantifying T wave loop morphology: relevance for assessment of heterogeneous repolarization

Regional and transmural heterogeneity of repolarization is known to contribute to arrhythmogenic conditions. We aimed to develop quantitative vectocardiographic parameters describing the overall T wave loop shape but more important, measures of subtle changes in the course of T wave loop, possibly reflecting sudden changes in the repolarization wavefront. The spatial vector magnitude, elevation and azimuth angles calculated for each sample of T wave loop were used to develop two tested parameters. The ratio of maximum to mean vector (RMMV) and mean difference of elevation and azimuth (DEA). Both parameters were computed in ECGs of LQTS gene carriers and their non-carrier family members. Increased values of DEA and RMMV found in LQTS carriers may reflect increased complexity (heterogeneity) of repolarization and encourage us to further explore this computerized approach quantifying T wave loop complexity.