Heart gate variability and occurrence of ventricular arrhythmias during balloon occlusion of a major coronary artery

Experimental studies suggest that autonomic mechanisms are important in the genesis of ischemia-induced malignant ventricular arrhythmias, but the role of the autonomic nervous system in human arrhythmogenesis is not well known. To assess whether heart rate variability (HRV) predicts the occurrence of ventricular arrhythmias during acute coronary artery occlusion, we performed continuous electrocardiographic, heart rate, and blood pressure recordings before and during a 2-minute balloon occlusion of a stenotic coronary artery in 252 patients with no baseline ventricular premature complexes (VPCs). The ranges of nonspecific responses in heart rate and blood pressure were determined by analyzing a control group of 19 patients with no ischemia during a 2-minute balloon inflation in a totally occluded coronary artery. Balloon occlusion of a coronary artery was stopped because of complex, i.e., bigeminal or repetitive, VPCs in 14 patients, and solitary (<5) VPCs were observed in an additional 19 patients. During coronary occlusion, HRV increased (p <0.001) and heart rate decreased (p < 0.05) in patients with no VPCs, whereas an opposite tendency to reduction in HRV (p = 0.08) was observed in patients with complex VPCs. Complex VPCs were observed in 5 (42%) of the 12 patients with a significant coronary occlusion-induced decrease in HRV, in 7 (3.5%) of 200 patients with no change in HRV, but in none of the 40 patients with a significant increase in HRV (p <0.001). Baseline HRV did not predict the occurrence of VPCs during coronary occlusion. Logistic regression analysis identified the decrease in HRV (p <0.001) to be the only independent predictor of complex VPCs. In conclusion, coronary occlusion-induced increase in HRV seems to protect against occurrence of complex ventricular arrhythmias during the early phase of abrupt coronary occlusion, suggesting that vagal activation may modify the outcome of acute coronary events in patients with coronary artery disease. (C) 1999 by Excerpta Medico, Inc.