Heart rate variability in patients with acute myocardial infarction undergoing primary coronary angioplasty

Depressed heart rate variability (HRV) has been associated with adverse out come during and after acute myocardial infarction (AMI). The effects of rep erfusion in AMI on the course of HRV have not been well characterized as ye t. We analyzed 123 consecutive patients with a first AMI who underwent succ essful reperfusion (Thrombolysis In Myocardial Infarction grades 2 and 3) b y primary percutaneous transluminal coronary angioplasty (PTCA). Time- and frequency-domain HRV was measured from 24-hour Holter monitoring, which beg an at hospital admission. Mean RR interval increased significantly after su ccessful PTCA, Reperfusion immediately caused an immediate transient depres sion of HRV, which was followed by a significant increase of HRV. Quantitat ive markers of sympathetic activity and sympathovagal balance, such as SD o f the averages of NN intervals in all 5-minute segments, and low- and/or hi gh-frequency ratio continuously decreased within the observation period. Pa tients with anterior AMI exhibited the same pattern of temporal changes of HRV, with, however, lower absolute values for HRV and mean RR interval than patients with non-anterior AMI. Subgroup analysis in 21 patients with repe rfusion >12 hours after onset of pain showed that the biphasic profile of H RV and the marked increase of mean RR interval was absent. Furthermore, in patients with late reperfusion, HRV was significantly lower compared with t hose with early reperfusion. Thus, timely reperfusion in AMI leads to a bip hasic effect on autonomic tone, characterized by a transient suppression, f ollowed by a significant activation of the vagal tone, as well as an attenu ation of sympathetic activity. Recovery of HRV may contribute to the benefi ts of early reperfusion in AMI. (C)2000 by Excerpta Medica, Inc.