Electrophysiologic effects of quinaprilat in dogs during acute myocardial ischemia and following reperfusion

Background There have been few studies concerning the electrophysiologic ch anges associated with the use of angiotensin-converting enzyme inhibitors i n patients with acute myocardial infarction. We examined the electrophysiol ogic effects of quinaprilat in dogs during acute myocardial ischemia and fo llowing reperfusion, Methods The left anterior descending coronary artery was occluded for 10 mi n and reperfused for 10 min. Animals received intravenous quinaprilat (3 mu g/kg per min, quinaprilat group) or saline (control group). We measured th e ventricular effective refractory period and intra-myocardial conduction t ime within the left anterior descending coronary artery region (ischemic re gion) during myocardial ischemia and following reperfusion, and determined the frequency of ventricular fibrillation, Results The effective refractory period in the ischemic region decreased du ring myocardial ischemia, and decreased further immediately after reperfusi on in the control group. The intra-myocardial conduction time in the ischem ic region increased during myocardial ischemia but rapidly shortened after reperfusion in the control group. In the quinaprilat group, however, no sig nificant differences were evident between the ischemic and non-ischemic reg ions in either the effective refractory period or the intra-myocardial cond uction time during myocardial ischemia or following reperfusion. The percen tage shortening of the effective refractory period and the percentage prolo ngation of the intra-myocardial conduction time in the ischemic region were significantly lower in the quinaprilat group than in the control group dur ing myocardial ischemia and following reperfusion. The frequency of ventric ular fibrillation during myocardial ischemia and following reperfusion was significantly lower in the quinaprilat group (21%) than in the control grou p (74%; P < 0.01). Conclusions Quinaprilat protects against electrophysiologic abnormalities, and may decrease arrhythmias during acute myocardial ischemia and following reperfusion. Coronary Artery Dis 9:697-701 (C) 1998 Lippincott Williams & Wilkins.