The aim of the study was to determine the relation between QT dispersion and ventricular arrhythmia after myocardial infarction, as well as the effects of postinfarction scar size, cardiac function, and severity of coronary artery disease on QT dispersion. Three hundred three patients, 3 months after myocardial infarction, and a group of 21 healthy subjects were evaluated. QT dispersion was the difference between maximal and minimal QT interval in 12-ECG leads. Postinfarction scar size was determined by Selvester's QRS scoring system. Cardiac function was evaluated by echocardiography and exercise stress test, and the severity of coronary artery disease by the number and degree of coronary artery stenoses. QT dispersion increased significantly in relation to the severity of arrhythmia (< 50 premature ventricular complexes vs ventricular tachycardia; 61.6 [+/- 12.3] vs 84.8 [+/- 16.4] ms, P < 0.001). QT dispersion > 80 ms was associated with ventricular tachycardia with the sensitivity of 68% and specificity of 88%. QT dispersion also increased significantly, dependent on the postinfarction scar size (0% vs > or = 33% of left ventricular myocardium; 61.8 [+/- 16.4] vs 74.7 [+/- 16] ms, P < 0.001), as well as in the case of significantly impaired cardiac function. Although QT dispersion increased with the number of diseased vessels and the degree of stenoses, the differences were not significant (P > 0.05). In conclusion, QT dispersion is a risk marker of complex ventricular arrhythmia in the chronic stage of myocardial infarction. Multiple regression analysis indicates that only the postinfarction scar size has an independent effect on QT dispersion (R2 = 0.39, P < 0.05).

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.

Propranolol efficiency in prevention of sustained ventricular tachycardia in patients with implanted cardioverter-defibrillator: a case series LETTER TO THE EDITOR Croat Med

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