Effect of beta-blockade on the premature ventricular beats/heart rate relation and heart rate variability in patients with coronary heart disease and severe ventricular arrhythmias.

Abstract

We examined the effects of beta-blockers on the associations between heart rate and number of premature ventricular beats (PVBs) and on heart rate variability and myocardial ischemia in patients with coronary heart disease. After 2 weeks of run-in placebo treatment, 18 patients with coronary artery disease were randomized to a 7-day treatment with either propranolol (40 mg) three times a day or placebo. During run-in and after 7 days of treatment, patients underwent 24-hour Holter monitoring and exercise tests. We analyzed the 24-hour Holter recordings with customized software that computes the correlation between heart rate and occurrence of PVBs. We also computed spectral measures of heart rate variability on the same recordings. Propranolol caused a significant decrease in the log-transformed total number of PVBs recorded over 24 hours and during the day. The number of PVBs was much lower during the night than during the day both after placebo and after propranolol. There were no differences between the two treatments. During the day, there was a positive correlation between heart rate and the number of PVBs in all 18 patients. The mean correlation coefficients between heart rate and number of PVBs increased significantly after propranolol treatment both during the 24-hour monitoring (p < 0.05) and during the day (p < 0.05). The night-recorded correlation coefficients between heart rate and number of PVBs were not significantly different in the placebo versus propranolol group. Propranolol significantly increased the total power during the day. Placebo caused a significant decrease in the low-frequency band (LF) and a significant increase in the high-frequency band (HF) during the night compared with the day. During the day, propranolol significantly reduced LF power and increased HF power, with respect to placebo. After propranolol treatment, the values of LF and HF power during the day were comparable to those recorded at night. The LF/HF ratio decreased significantly after propranolol treatment with respect to placebo in the day and became similar to that recorded during sleep. Propranolol significantly reduced heart rate and systolic blood pressure at rest and at peak exercise and reduced signs of myocardial ischemia. Propranolol administration reduces PVBs in patients with coronary artery disease and severe ventricular arrhythmias possibly through an improvement of cardiac autonomic regulation and through anti-ischemic effects, antiarrhythmic effects, or both.