QT dispersion ratio in patients with unstable angina pectoris (a new risk factor?).

Abstract

QT dispersion has been shown to be associated with fatal arrhythmias and sudden death in coronary artery disease. A recent study indicated that marked QT dispersion in electrocardiograms (ECGs) obtained during acute ischemia demonstrated a significant correlation with ventricular fibrillation. This study investigated the ECG parameters for repolarization (QT dispersion, corrected QT, corrected QT dispersion, and QT dispersion ratio) and their interrelation with acute ischemia. QT parameters as well as a newly developed repolarization index, QT dispersion ratio [(QT dispersion/RR interval) x 100] were calculated digitally during rest and ischemia in 32 patients with coronary artery disease (rest angina, Braunwald class III). Results were correlated with clinical consequences, mainly arrhythmias, within a follow-up period of 5 +/- 2 days. While most patients had an increase in all four parameters, only the QT dispersion ratio showed a significant difference when correlated with ventricular arrhythmias (p < 0.001, F ratio = 38). QT dispersion ratio appears to be a new and promising parameter in predicting ventricular arrhythmias in patients with acute ischemia.