Effect of angiotensin-converting enzyme inhibitors on the power spectrum of heart rate variability in post-myocardial infarction patients

Abstract

Background: Heart rate variability (HRV) time and frequency domain indices are strong predictors of malignant arrhythmias and sudden cardiac death. The effect of various angiotensin-converting enzyme (ACE) inhibitors on HRV in patients with acute myocardial infarction (AMI) has not been studied.

Methods: Ninety patients with uncomplicated AMI (age range 39-75 years, median 61 years) were assigned randomly to six groups of 15 patients each. They were treated with placebo or one of the following ACE inhibitors for 30 days: captopril, cilazapril, enalapril, lisinopril or quinapril. HRV was assessed 3 days after the onset of AMI (baseline), and 30 days after treatment. Fifteen patients with stable coronary artery disease and 15 healthy volunteers, age- and sex-matched with AMI patients, served as controls.

Results: At baseline, time and frequency domain HRV indices in the AMI groups were equally less than those in patients with stable coronary artery disease and normal volunteers. Compared with placebo, quinapril, lisinopril and captopril changed frequency domain HRV indices 30 days after initiation of treatment, indicating an increase in vagal tone, whereas enalapril and cilazapril had no significant effect on these indices. Most of the time domain HRV indices 30 days after initiation of treatment increased significantly in all patients treated with ACE inhibitors, but remained unchanged in the placebo group. Frequency domain and time domain HRV indices 30 days after treatment in the quinapril group did not differ statistically from those in patients with stable coronary artery disease, but were less than those in normal volunteers.

Conclusions: Quinapril, lisinopril and captopril improved frequency domain HRV indices related to vagal tone, whereas cilazapril and enalapril had no effect on these indices. This influence of some ACE inhibitors on HRV may be beneficial in reducing the risk for sudden death in post-myocardial infarction patients.