QT INTERVAL DISPERSION IN CHRONIC HEART-FAILURE AND LEFT-VENTRICULAR HYPERTROPHY - RELATION TO AUTONOMIC NERVOUS-SYSTEM AND HOLTER TAPE ABNORMALITIES

Objective-To study QT dispersion in left ventricular hypertrophy and c hronic heart failure and to determine the relation to ventricular arrh ythmias. Setting-Investigational laboratory of a tertiary referral cen tre. Study design-Patients with left ventricular hypertrophy and norma l systolic (n = 14) and patients with heart failure (n = 18) were matc hed with controls (n = 17). The QT dispersion was examined in relation to abnormalities in resting mechanical and autonomic function and to the findings of 24 hour Holter monitoring. Main outcome measures-QT di spersion is the difference between the maximum and the minimum QT valu es from the 12 lead electrocardiogram. Mean(SD) QT dispersion from the 10 lead electrocardiogram was also examined once the 12 lead minimum and maximum values had been removed. The QT distribution is the curve describing the distance from the mean for all QT intervals (ms). Resul ts-All measures of QT dispersion were increased significantly in left ventricular hypertrophy and tended to increase in those with heart fai lure. The QT distribution was abnormal in both heart failure and left ventricular hypertrophy. There was no relation between the degree of c hange in QT dispersion and the incidence of ventricular arrhythmia on 24 hour Holter monitoring. Also there was no relation between QT dispe rsion and autonomic or mechanical abnormalities. The QT dispersion was related to QRS duration. Conclusion-Though QT dispersion and distribu tion are abnormal in left ventricular hypertrophy these findings do no t support the hypothesis that QT dispersion reflects arrhythmic risk i n either hypertrophy or heart failure.