HEART-RATE-VARIABILITY IN PATIENTS WITH THE FIRST AND RECURRENT MYOCARDIAL-INFARCTION

Impairment of heart rate variability (HRV) has been reported in patien ts after myocardial infarction (MI). However, it is currently unknown whether the similar alterations of autonomic profile that accompany th e first MI will evolve after a recurrent MI. Forty male outpatients wi th a previous first MI (group I) and 20 age-matched male patients with a recurrent MI (group II) were studied and measures of HRV were estim ated from 24-hour electrocardiograms. In comparison with group I, grou p II had significantly higher values of ratio of low to high-frequency power (6.9 +/- 5.7 vs 3.7 +/- 1.8, respectively, p < 0.05), and a ten dency to lower values of all other measures of HRV. We conclude our st udy indicates that in comparison to group I, group II demonstrated aug mented sympathetic drive as assessed by the indices of HRV. The shift toward adrenergic predominance detected after recurrent MI may result from altered afferent feedback from abnormally contracting left ventri cular segments to the autonomic modulation of sinus node, or accompany subclinical state of heart failure not readily accessible with hemody namic measurements.