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; / ) <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>005). 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%. ConclusionLarge 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.

Changes in ventricular repolarization during percutaneous transluminal coronary angioplasty in humans assessed by QT interval, QT dispersion and T vector loop morphology

“…Explanations for this could be an insufficient degree of dispersion, an absence of a critically timed extrasystole, or a combination of these. According to reports on postmyocardial infarction patients with spontaneous and/or inducible ventricular arrhythmia, a QT or QT c dispersion of at least 80–90 ms might be a critical level [15, 18, 30] and was present in almost half of our patients. The degree of dispersion of ventricular repolarization therefore seemed enough to put several of our patients at risk of a malignant arrhythmia.…”

New approach for T-wave end detection on electrocardiogram: Performance in noisy conditions

“…QTD and QTV are techniques relatively recent in comparison with QTL, but there are reports of studies showing high QTV for isquemic patients [2] and high QTD as a marker of tachycardia ventricular [3]. …”

Dispersion in Ventricular Repolarization in Patients with Severe Intraventricular Conduction Disturbances

“…[7][8][9] Increased dispersion of ventricular repolarization, as reflected by invasive or noninvasive techniques, has been related to increased susceptibility to arrhythmia in animal models and in humans. [10][11][12][13][14][15][16][17][18][19][20] Several methods have been used for the assessment of the recovery of ventricular excitability in humans: the extrastimulus (S 1 S 2 ) method, 21 the same method combined with the recording of monophasic action potential duration and activation time, 22,23 measurement of local fibrillation intervals, 24,25 and noninvasively from the dispersion of the QT and corrected QT (QTc) intervals on the 12-lead surface electrocardiograph (ECG). 13 Previous observations suggest that the susceptibility to spontaneous or inducible polymorphic ventricular arrhythmia, is related to an increased dispersion of refractoriness, while monomorphic ventricular tachycardia (VT) is related to increased dispersion of activation time (conduction velocity).…”