OBJECTIVES We investigated the effect of carvedilol on corrected QT dispersion (QTd) in patients with congestive heart failure (CHF).
STUDY DESIGN The study included 20 patients (6 females, 14 males; mean age 57±11 years) who had symptomatic CHF with sinus rhythm, resting ejection fraction ≤%40, and no contraindications for beta-blockers. Coronary angiography showed coronary artery disease in nine patients, and dilated cardiomyopathy in 11 patients. Eight patients had myocardial infarction previously. All the patients had been receiving diuretics and angiotensin-converting enzyme inhibitors for one year. Carvedilol was initiated with a minimum dose of 3.125 mg twice daily, to be increased biweekly to reach the maximum tolerable dose (mean daily dose 42.5±13.6 mg). All the patients were assessed by electrocardiography and transthoracic echocardiography before and three months after treatment.
RESULTS Significant decreases were observed in the following clinical and echocardiographic parameters: heart rate (p=0.001), systolic blood pressure (p=0.002), left atrial diameter (p<0.001), and left ventricular end-systolic (p<0.001) and end-diastolic (p=0.04) diameters. Left ventricular ejection fraction showed a significant increase (p<0.001). There was also a remarkable improvement in NYHA functional capacity in all the patients (p<0.05). Both corrected QTd (p=0.001) and QTd (p<0.001) significantly decreased. Maximum corrected QT and maximum QT did not change significantly (p>0.05), while minimum QT and minimum corrected QT significantly increased (p<0.001). No significant correlation was found between the carvedilol dose and the percent decrease in QTd (p>0.05).
CONCLUSION Carvedilol is associated with significant decreases in corrected QTd in patients with CHF.
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