Spatial aspects of ventricular repolarization in postinfarction patients

QT dispersion has been proposed to reflect the heterogeneity of ventricular repolarization, but a poor reproducibility limits its clinical usefulness. Spatial vectorcardiographic descriptors constitute a novel approach to qua ntify ventricular repolarization. To test the ability of vectorcardiographi c descriptors to discriminate among different subsets of postinfarction pat ients, 50 consecutively recruited patients with acute MI, 50 patients with history of an old (> 6 months) MI and 50 healthy controls were evaluated. T he maxim um and minim um QT and JT intervals and QT and JT dispersion were manually measured from a digitally recorded 12-lead EGG. X, Y, and Z leads were reconstructed from the 12-lead EGG. The amplitude of the maximum spati al T vector (spatial T amplitude), the angle between the maximum spatial QR S and T vectors (spatial QRS-T angle), and the frontal plane QRS-T angle we re automatically calculated The spatial T amplitude and the spatial QRS-T a ngle did nor differ between patients with a recent and those with an old MI (P = 1). QT dispersion was significantly lower in patients with an old MI than in patients with a recent one (P = 0.002). The spatial repolarization descriptors showed better short-term reproducibility than the dispersion in dices. In conclusion, the spatial T amplitude and the spatial QRS-T angle a re accurate measures of ventricular repolarization that do not differ betwe en patients with recent and those with old MI. The different QT dispersion values observed in this study between the two post-MI groups should be cons idered cautiously because of the low accuracy of the manual measurements.