QT dispersion, daily variations, QT interval adaptation and late potentials as risk markers for ventricular tachycardia

Abstract

Aims. The aim of the study was to determine the value and correlation between QT dispersion, daily variations in the QT interval and late potentials as risk markers for ventricular tachycardia. Methods and results. QT dispersion was defined as the difference between the longest and the shortest QT interval in 12 electrocardiographic leads, QTc variability as the difference between the maximal and minimal QTc interval during 24-h Holter monitoring and QT interval adaptation as the regression line between heart rate and the uncorrected QT interval. One hundred and forty-five patients, 3 months after myocardial infarction were included in the study. QT dispersion significantly increased with the severity of arrhythmia (modified Lown's classification; P < 0.001). The level of 80 ms was associated with ventricular tachycardia with a sensitivity of 72.7% and a specificity of 86.4%. The greater daily variability of the QTc interval in patients with ventricular tachycardia was insignificant (P > 0.05). QT interval adaptation did not discriminate between patients with ventricular tachycardia from those in other groups. Late potentials were associated with ventricular tachycardia with a sensitivity of 50% and a specificity of 90.3%. Conclusion. Large QT dispersion and late potentials were risk markers for ventricular tachycardia, but there was no correlation between QT dispersion, daily variations in the QT interval and late potentials in patients 3 months after myocardial infarction.