Autonomic patterns preceding and following accelerated idioventricular rhythm in acute myocardial infarction

Introduction: We have investigated the potential relationship between cardi ac autonomic activity and accelerated idioventricular rhythm (AIVR) in resp onse to reperfusion in the setting of an acute myocardial infarction (AMI) through spectral analysis of heart rate variability (HRV). Methods and Resu lts:We studied 16 patients with AMI who developed spontaneous sustained AlV R after initiation of intravenous thrombolysis. Sympathovagal interactions were evaluated by analysis of the low- (LF) and high-frequency (HF) spectra l components of HRV for each 5-min interval over the 30-min periods precedi ng and following AIVR. The occurrence of AlVR was related to the ST-segment elevation resolution and the angiographic evidence of restored coronary fl ow to assess timely reperfusion and sustained coronary artery patency. The analysis of spectral components over time revealed combined responses of bo th autonomic limbs preceding and following AIVR, which were not followed by corresponding changes in heart rate. Ten minutes before AIVR, there was a characteristic continuous increase in LF, in the setting of a concomitant w ithdrawal of HF, suggestive of a progressive sympathetic predominance. Afte r the end of AIVR, the opposite pattern was found with an increased HF and decreased LF, indicative of parasympathetic rebound overactivity. All patie nts showed signs of fast reperfusion and complete restoration of coronary f low. Conclusion: Our results indicate that reperfusion-induced AIVR is modu lated by sympathetic stimulatory effects, whereas a counterregulatory vagal response seems to exert a profound effect upon its suppression. Clinically , the occurrence of early sustained AIVR appears to offer reliable informat ion about both timely reperfusion and sustained and effective coronary arte ry patency. Copyright (C) 2001 S. Karger AG, Basel.