The effects of diltiazem on QT-interval duration and dispersion in patients with unstable angina

Abstract

This study was designed to determine whether diltiazem treatment in patients with unstable angina would reduce QT-dispersion as an indicator of cardiac arrhythmia. In a double blind and placebo control study, 72 patients (56 +/- 12 years old) were randomized to oral diltiazem (60 mg/8 h) or placebo. Standard 12-lead ECG was recorded four times: before and at the 24(th), 48(th), and 100(th) hours of diltiazem or placebo ingestion. All QT parameters were corrected for the heart rate. QT intervals and QT dispersion were not significantly different at any times between groups. The corrected QT dispersion in diltiazem treated patients before and 24, 48, and 100 hours after the drug administration were 66 +/- 28; 63 +/- 17; 62 +/- 22 and 62 +/- 21 ms, respectively (p > 0.05). These values in patients received placebo were 72 +/- 30; 60 +/- 28; 56 +/- 32 and 65 +/- 46 ms. Thus, diltiazem neither reduce QT intervals nor QT dispersion in patients suffering from unstable angina, suggesting that diltiazem has no effects on prevention of cardiac arrhythmias in these patients.