Effects of Carvedilol Therapy on Arrhythmia Markers in Patients With Congestive Heart Failure

Abstract

SUMMARYThe aim of this study was investigate the effects of carvedilol therapy on ventricular repolarization characteristics as assessed by QT dispersion (QTd) and heart rate variability (HRV) in patients with heart failure.Thirty-one patients with heart failure (mean age, 63.9 years) were included in the study. Carvedilol was administered in addition to standard therapy for CHF at a dose of 6.25 mg/day and uptitrated to the maximum tolerated dose. Control group consisted of 14 patients with heart failure (mean age, 69.4 years) who could not take carvedilol due to several reasons. All patients were followed-up 6 months. QT dispersion (QTd), and corrected QTd (QTcd) values were calculated at baseline and at the end of follow-up. Time domain and frequency domain heart rate variability analysis were performed with ambulatory Holter ECG.Mean carvedilol dose was 23.9 ± 13.9 mg. Significant reductions were observed in the QTd (P = 0.016) and QTcd (P = 0.001) with carvedilol therapy, whereas QTd (P = 0.47) and QTcd (P = 0.43) did not change significantly in the control group. The QT maximum value did not change significantly but the QT minimum value (P = 0.03) was significantly increased after carvedilol therapy. Although the mean SDANN value was improved (P = 0.039), other HRV parameters such as mean SDNN (P = 0.32), rMSSD (P = 0.74), and the LF/HF ratio (P = 0.35) did not change significantly after carvedilol therapy.This prospective controlled study shows that carvedilol therapy decreased QT dispersion and improved ventricular repolarization characteristics but did not change autonomic dysfunction in patients with heart failure. (Int Heart J 2006; 47: 565-573)

The Comparative Effects of Long-Term Carvedilol versus Bisoprolol Therapy on QT Dispersion in Patients with Chronic Heart Failure

“…It is believed that one of the mechanisms of the favorable effects of β-blockers may be their preventive effect on fatal arrhythmia by reducing QT interval and QTD. Consistent with this belief is the finding that a long-term therapy with different β-blockers decreases QTD in CHF [10,11,12,13,14]. …”

“…Whereas some reported that increased QTD and QTcD did not have a prognostic value in patients with CHF [19, 20], most of them showed that both are reliable markers to predict patients with a high risk [3,4,5,6, 21, 22]. QTD, on the other hand, is one of the parameters reported to be used in evaluating the efficaciousness of β-blockers [23], and in previous studies, it was shown that different β-blockers, including carvedilol and bisoprolol, decreased QTD and QTcD in various cardiac disorders [10,11,12,13,14, 24, 25]. …”

“…Furthermore, after the release of the COMET study, it has been speculated that metoprolol dosing is not optimal, unlike carvedilol. Carvedilol, like the other β-blockers, also causes a decrease in QTD and QTcD in patients with CHF [12,13,14]. Furthermore, it has been shown that this decrease starts at an early stage of the treatment and that the effect increases in parallel to the dose administered and the duration of the therapy [12, 13].…”

Gender Differences in Circulatory Response Measured by the Double Product Break-Point Method

“…Cardiac rehabilitation programs are based on electrocardiography, cardiac ultrasonography, angiography, and evaluation of exercise tolerance to measure the anaerobic threshold using oxygen uptake kinetics [1][2][3][4][5][6][7][8][9][10][11][12][13] . Tanaka et al 8) developed the DPBP method, a simple method for measuring the anaerobic threshold (AT) and lactate threshold (LT).…”

“…There have been numerous studies on the effects of gender and age using static evaluations 1,2,11,12) . Most of these studies reported arrhythmias, and there have been numerous studies reporting oxygen uptake kinetics and heart rate threshold in relation to exercise tolerance, gender and age [3][4][5][6][7][8][9] .…”