EFFECT OF ANGIOTENSIN-CONVERTING ENZYME-INHIBITORS ON THE POWER SPECTRUM OF HEART-RATE-VARIABILITY IN POSTMYOCARDIAL INFARCTION PATIENTS

Background Heart rate variability (HRV) time and frequency domain indi ces are strong predictors of malignant arrhythmias and sudden cardiac death. The effect of various angiotensin-converting enzyme (ACE) inhib itors on HRV in patients with acute myocardial infarction (AMI) has no t been studied. Methods Ninety patients with uncomplicated AMI (age ra nge 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 fol lowing ACE inhibitors for 30 days: captopril, cilazapril, enalapril, l isinopril 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-matche d 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 volu nteers. Compared with placebo, quinapril, lisinopril and captopril cha nged frequency domain HRV indices 30 days after initiation of treatmen t, indicating an increase in vagal tone, whereas enalapril and cilazap ril had no significant effect on these indices. Most of the time domai n HRV indices 30 days after initiation of treatment increased signific antly in all patients treated with ACE inhibitors, but remained unchan ged in the placebo group. Frequency domain and time domain HRV indices 30 days after treatment in the quinapril group did not differ statist ically from those in patients with stable coronary artery disease, but were less than those in normal volunteers. Conclusions Quinapril, lis inopril and captopril improved frequency domain HRV indices related to vagal tone, whereas cilazapril and enalapril had no effect on these i ndices. This influence of some ACE inhibitors on HRV may be beneficial in reducing the risk for sudden death in post-myocardial infarction p atients.