DISPERSION OF VENTRICULAR REPOLARIZATION IN DILATED CARDIOMYOPATHY

Objective Increased dispersion of ventricular repolarization has been shown to be a marker for increased risk of ventricular tachyarrhythmia s in various cardiac disorders. The present study is aimed at comparin g the values of four dispersion indices in four clinical groups: norma l subjects (n=23), patients with intraventricular conduction defects ( QRS>0.12 s) without underlying cardiac disease (n=30), patients with d ilated cardiomyopathy (n = 36), and patients with both dilated cardiom yopathy and ventricular conduction defects (n = 18). Methods On an ave raged cycle from a 10s record of 15 simultaneous leads (12-lead ECG an d XYZ leads), and after interactive editing, four intervals were compu ted: JTapex, JTend, QTapex and QTend. For each interval, the dispersio n is defined as the difference between the maximal and minimal values across the 15 leads. Results The mean values of all four dispersion in dices were significantly smaller in the normal group than in the three other groups (P<0.001). Among patients with dilated cardiomyopathy, t hose with intraventricular conduction defects had significantly higher dispersion values than those without, even disregarding the QRS durat ion (P<0.01). Thus, patients with both dilated cardiomyopathy and vent ricular conduction defects have larger dispersion values than patients with ventricular conduction defects alone (P<0.01) and than those wit h dilated cardiomyopathy without intraventricular conduction defects. Conclusion Dispersion of ventricular repolarization is increased in pa tients with dilated cardiomyopathy, especially in those with ventricul ar conduction defects, suggesting that they are at higher risk of arrh ythmic events.