Clinical research
Does carvedilol therapy reduce QT dispersion in patients with heart failure?

Introduction: Carvedilol therapy increases left ventricular ejection fraction, and reduces mortality and morbidity rates. However, there are very limited data relating to the effect of carvedilol on QT dispersion (QTd). In this study, we investigated the effect of carvedilol therapy on QTd in patients with heart failure.

Material and methods: Fifty-six patients with heart failure and a left ventricular ejection fraction less than 40% were prospectively included in the study. Clinical examination, determinations of plasma levels of tumour necrosis factor-a (TNF-α), interleukin 2 (IL-2) and IL-6, electrocardiography and radionuclide study were performed at baseline and repeated at the end of the 4th month of carvedilol therapy. From standard 12-lead electrocardiograms the maximum and minimum QT intervals, corrected QT intervals and corrected QTd values were calculated at baseline, and after the 4th month of carvedilol therapy.

Results: At the end of the 4th month, IL-6 (from 9.8±6.4 to 5.4±0.7 pg/ml) and TNF-α (from 10.9±4.6 to 6.0±4.9 pg/ml) levels, QTd, corrected QTd, resting heart rate, and systolic blood pressure were significantly decreased, and left ventricular ejection fraction and NYHA functional class were improved by carvedilol therapy (QTd from 66±22 to 28±13 ms, P<0.001, corrected QTd from 72±23 to 30±14 ms, P<0.001). However, maximum corrected QT and maximum QT values did not change significantly, while minimum QT and minimum corrected QT values significantly increased.

Conclusions: Carvedilol therapy for 4 months resulted in a significant reduction in QTd.