Electrocardiographic measures of ventricular repolarisation dispersion in patients with coronary artery disease susceptible to ventricular fibrillation.

Abstract

To study electrocardiographic measures of ventricular repolarisation dispersion in patients prone to ventricular fibrillation compared with controls matched for the extent of coronary heart disease and the use of beta blockers. A case-control study. Cardiovascular laboratory of a tertiary referral centre. Fifty patients with documented ventricular fibrillation not associated with acute myocardial infarction, and their controls matched for sex, age, number of diseased coronary vessels, left ventricular ejection fraction, previous myocardial infarction and its location, and the use of beta blockers. Electrocardiographic measures of QT, JT, and Tend interval dispersions in a 12 lead electrocardiogram. The ventricular fibrillation patients compared to controls showed increased mean (SD) QTapex dispersion (53 (18) ms v 44 (18) ms, respectively; p < 0.01) and mean (SD) Tend dispersion (46 (17) ms v 38 (15) ms, respectively; p < 0.05). Increased QTapex and Tend dispersions are associated with a susceptibility to ventricular fibrillation even when the extent of the coronary heart disease and use of beta blockers are taken into consideration. However, because of a considerable overlap between the groups, measures of QT dispersion assessed from a 12 lead electrocardiogram do not provide clinically useful information for identification of patients at risk of sudden cardiac death.