Beat-to-beat QT interval variability in coronary patients.

Changes in ventricular repolarization have been described in patients after myocardial infarction, whereas data for coronary patients without prior myocardial infarction are lacking. This study was designed to evaluate ventricular repolarization in coronary patients with effort angina pectoris. Beat-to-beat QT interval variability (QTV) using 5-minute resting high-resolution ECG recordings was measured in 26 men (mean age 62.1 years) with effort angina pectoris and without prior myocardial infarction, and in 30 age-matched men without clinically evident coronary heart disease (controls). To evaluate the degree of coronary artery disease in coronary patients, coronary angiography was performed. Coronary patients displayed significantly higher values of QTV compared with the control patients (P < .001). Rate adaptation of QT interval correlated significantly with the degree of coronary artery disease in the study group patients (P < .05). The significant association between QTV and coronary heart disease suggests altered ventricular repolarization in coronary patients without prior myocardial infarction.