ELECTROCARDIOGRAPHIC MEASURES OF VENTRICULAR REPOLARIZATION DISPERSION IN PATIENTS WITH CORONARY-ARTERY DISEASE-SUSCEPTIBLE TO VENTRICULAR-FIBRILLATION

Objective-To study electrocardiographic measures of ventricular repola risation dispersion in patients prone to ventricular fibrillation comp ared with controls matched for the extent of coronary heart disease an d the use of beta blockers. Design-A case-control study. Setting-Cardi ovascular laboratory of a tertiary referral centre. Patients-Fifty pat ients with documented ventricular fibrillation not associated with acu te myocardial infarction, and their controls matched for sex, age, num ber of diseased coronary vessels, left ventricular ejection fraction, previous myocardial infarction and ifs location, and the use of beta b lockers. Main outcome measures-Electrocardiographic graphic measures o f QT, JT, and T-end interval dispersions in a 12 lead electrocardiogra m. Results-The ventricular fibrillation patients compared to controls showed increased mean (SD) QT(apex) dispersion (53 (18) ms v 44 (18) m s, respectively; p < 0.01) and mean (SD) T-end dispersion (46 (17) ms v 38 (15) ms, respectively; p < 0.05). Conclusions-Increased QT(apex) and T-end dispersions are associated with a susceptibility to ventricu lar fibrillation even when the extent of the coronary heart disease an d use of beta blockers are taken into consideration. However, because of a considerable overlap between the groups, measures of QT dispersio n assessed from a 12 lead electrocardiogram do not provide clinically useful information for identification of patients at risk of sudden ca rdiac death.