Limitation of infarct size and ventricular remodeling in patients with completely reperfused anterior acute myocardial infarction - The potential role of ischemia time

Background: Experimental studies suggest that coronary reperfusion does not result in appreciable myocardial salvage beyond 3 to 4 h. Hypothesis: The present study was undertaken to examine the potential role of ischemia time as a determinant of infarct size and cardiac function in humans. Methods: Ninety patients (69 men, 21 women, aged 61 +/- 1 years) presented within 24 h of onset of a first anterior infarct had ST segment elevation on electrocardiogram. All patients underwent coronary intervention within 24 h of onset of symptoms and obtained complete reperfusion of the infarct-related artery. Results: Infarct size expressed as a percentage of the area at risk (IS/RA) and left ventricular end-diastolic volume (LVEDV) were significantly (p < 0.017) smaller and left ventricular ejection fraction (LVEF) assessed by left ventriculography (35 4 days) was significantly higher in patients treated within 4 h after onset (IS/RA:55 +/- 4%, LVEDV: 127 7 ml, LVEF: 62 +/- 2%) than in those treated 4 to 12 h (97 2%, 140 +/- 13 ml, 52 +/- 3%) and 12 to 24 h (93 +/- 2%,163 +/- 14 ml, 49 +/- 5%) after symptom onset. Left ventricular end-diastolic volume was significantly smaller in patients treated 4 to 12 h after onset than in those treated 12 to 24 h after onset. Conclusions: Patients with < 4 h of myocardial ischemia exhibited significant myocardial salvage and better left ventricular function and patients with 4 to 12 h of myocardial ischemia exhibited significantly smaller LVEDV than those with more prolonged ischemia, although there was no difference in final infarct size.