T-wave morphology differences between patients with and without arrhythmic complication of ischemic heart disease.

The study investigated the differences in T-wave morphology between normal controls, patients with an uncomplicated follow-up after a myocardial infarction (MI), and patients with ischaemic heart disease and a history of ventricular tachycardia/fibrillation (VT/VF). The study population consisted of 164 healthy patients (age 53.4 +/- 18.7 years old, 80 women), 123 VT/VF patients (age 63.8 +/- 10.1 years old, 15 women), and 196 MI patients (age 59.2 +/- 10.0 years old, 23 women). In all patients, supine resting signal-averaged orthogonal electrocardiograms were obtained. After singular value decomposition of electrocardiogram signal, 2 T-wave morphology descriptors were calculated: total cosine R to T describing the global angle between repolarisation and depolarisation loops, and percentage of loop area expressing the irregularity of the T-wave loop (a more irregular wave results in a lower percentage of loop area value). Both parameters were practically uncorrelated (Controls: r = - .106, MI r = .161, and VT/VF r = .173) and different between individual groups of patients: total cosine R to T (Control vs. MI: P = 4.3 x 10(-8), Control vs. VT/VF: P = 2.7 x 10(-16), MI vs. VT/VF: P = 3.1 x 10(-6)), percentage of loop area (Control vs. MI: P = 0.07, Control vs. VT/VF: P = 1.1 x 10(-8), MI vs. VT/VF: P = 2.9 x 10(-5), all nonparametric Mann-Whitney test). The comparisons of cumulative histograms also revealed significant differences between all three groups for both parameters (Kruskal-Wallis ANOVA test). Thus, these numerical descriptors of T-wave morphology are powerful indicators of arrhythmic complications among patients with ischaemic heart disease. They also differentiate between patients with stable uncomplicated ischaemic heart disease and healthy controls.