LEFT-VENTRICULAR HYPERTROPHY AND QT DISPERSION IN HYPERTENSION

The interlead variation in QT length on a standard electrocardiograph reflects regional repolarization differences in the heart. To investig ate the association between this interlead variation (QT dispersion) a nd left ventricular hypertrophy, we subjected 100 untreated subjects t o 12-lead electrocardiography and echocardiography. Additionally, 24 p reviously untreated subjects underwent a 6-month treatment study with ramipril and felodipine. In the cross-sectional part of the study, QT dispersion corrected for heart rate (QTc dispersion) was significantly correlated with left ventricular mass index (r = .30, P < .01), systo lic pressure (r = .30, P < .01), the ratio of peak flow velocity of th e early filling wave to peak flow velocity of the atrial wave (E/A rat io) (r = -.22, P = .02), isovolumic relaxation time (r = .31, P < .01) , and age (r = .21, P < .04). In the treatment part of the study, lead -adjusted QTc dispersion decreased from 24 to 19 milliseconds after tr eatment, and after a subsequent 2 weeks of drug washout remained at 19 milliseconds (P < .01). The changes in left ventricular mass index at these stages were 144, 121, and 124 g/m(2) (P < .01). Systolic pressu re decreased from 175 to 144 mm Hg and increased again to 164 mm Hg af ter drug washout (P < .01). The E/A ratio (0.97, 1.02, and 1.02; P = . 69) and isovolumic relaxation time (111, 112, and 112; P = .97) remain ed unchanged through the three assessment points. In conclusion, QT di spersion is increased in association with an increased left ventricula r mass index in hypertensive individuals. Antihypertensive therapy wit h ramipril and felodipine reduced both parameters. If an increased QT dispersion is a predictor of sudden death in this group of individuals , then the importance of its reduction is evident.