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Effect of beta-blockade on heart rate variability in patients with coronary artery disease
M J Niemelä1, K E Airaksinen, H V Huikuri
1Department of Medicine, University of Oulu, Finland.
Insights
Beta-blockade with metoprolol and atenolol significantly improves heart rate variability in patients with coronary artery disease. This enhancement in cardiac autonomic control may contribute to the protective benefits of beta-blockers in ischemic heart disease.
Area of Science:
- Cardiology
- Autonomic Nervous System Function
- Pharmacology
Background:
- Low heart rate variability (HRV) is prevalent in coronary artery disease (CAD) and linked to higher mortality.
- Beta-adrenergic blocking drugs are known to increase HRV in healthy individuals.
- Limited data exists on the impact of beta-blockade on HRV in patients with uncomplicated CAD.
Purpose of the Study:
- To evaluate the effects of beta-blockade on HRV in patients with CAD.
- To compare the impact of controlled-release metoprolol and atenolol on electrocardiographic measures of cardiac autonomic control.
- To determine if metoprolol and atenolol have differential effects on HRV.
Main Methods:
- A randomized, double-blind, crossover study design was employed.
- 18 male patients with stable CAD received 200 mg controlled-release metoprolol, 100 mg atenolol, or placebo daily for three 2-week periods.
- 24-hour HRV was assessed using time and frequency domain analyses.
Main Results:
- Beta-blockade significantly increased HRV, with no significant differences between metoprolol and atenolol.
- High frequency power increased by 64% (atenolol) and 62% (metoprolol).
- Both drugs blunted the post-arousal decrease in high frequency power, but did not affect the circadian rhythm amplitude.
Conclusions:
- Metoprolol and atenolol enhance HRV in patients with CAD.
- This improvement in cardiac autonomic control may underlie the cardioprotective effects of beta-blockade in ischemic heart disease.
Objectives:
This study assessed the effects of beta-blockade on heart rate variability in patients with coronary artery disease and determined whether the effects of metoprolol in a controlled-release formulation and atenolol differ with regard to electrocardiographic measures of cardiac autonomic control.
Background:
Low heart rate variability is common in coronary artery disease and is associated with increased mortality. Beta-adrenergic blocking drugs may increase heart rate variability in healthy subjects, but there is limited knowledge of whether they are able to modify heart rate variability in patients with uncomplicated coronary artery disease.
Methods:
In a randomly allocated, double-blind crossover study with three 2-week treatment periods, 200 mg of controlled-release metoprolol once a day, 100 mg of atenolol once a day or placebo once a day were administered in 18 male patients with stable coronary artery disease. The 24-h heart rate variability was measured in both the time and frequency domains.
Results:
Beta-blockade induced a significant increase in heart rate variability, but no significant differences were found between atenolol and metoprolol. The average 24-h high frequency power increased by 64% after atenolol and by 62% after metoprolol. The root-mean-square successive difference of normal RR intervals increased by 70% after atenolol and by 62% after metoprolol, and the standard deviations of RR intervals increased by 20% and 16%, respectively. Beta-blockade had no significant effects on the amplitude of the circadian rhythm of heart rate variability, although both metoprolol and atenolol blunted the abrupt decrease of high frequency power after arousal.
Conclusions:
Beta-blockade by metoprolol and atenolol enhance the heart rate variability in patients with coronary artery disease. This may contribute to the protective effects of beta-blockade in ischemic heart disease.