Differential effects of reperfusion on incidence of ventricular arrhythmias and recovery of ventricular function at 4 days following coronary occlusion.

To determine the influence of coronary reperfusion on ventricular arrhythmias and ventricular function at 4 days post occlusion, anesthetized dogs randomly received no occlusion (sham), permanent occlusion, or 1-, 2-, 3-, 4-, or 6-hour occlusions of the left anterior descending coronary artery, followed by reperfusion. An ambulatory ECG was recorded between 78 and 96 hours. The total runs of ventricular tachycardia were 1 +/- 0 (sham), 155 +/- 101 (1 hour), 66 +/- 32 (2 hours), 56 +/- 35 (3 hours), 167 +/- 68 (4 hours), 942 +/- 618 (6 hours), and 1422 +/- 486 (permanent occlusion); the runs of ventricular tachycardia were significantly less in the combined 1- to 4-hour groups (93 +/- 24) compared to the 6-hour and permanent occlusion groups (1282 +/- 384; p less than 0.006). Similar results were obtained for the number of hours in which ventricular tachycardia or frequent ventricular premature beats occurred. At 96 hours, improvement in percent systolic wall thickening of the ischemic myocardium assessed by two-dimensional echocardiography was seen in the group reperfused at 1 hour (p less than 0.01). Similar results were obtained for the reduction in degrees of wall circumference showing systolic thinning. In summary, at 4 days post occlusion in a dog model, spontaneous ventricular arrhythmias are reduced by reperfusion within 4 hours, while return of ventricular function is only improved by reperfusion within approximately 1 hour of coronary occlusion.