Time dependence of left ventricular recovery after delayed recanalization of an occluded infarct-related coronary artery: findings of pilot study

Objectives. We sought to test the hypothesis that late recanalization of infarct-related coronary arteries (IRAs) improves long-term left ventricular (LV) function. Background. Reperfusion within 24 h of an acute myocardial infarction (MI) has been shown to improve myocardial healing and to reduce infarct expansion. Uncontrolled dat suggest that there may be time window of several weeks for such an effect. Methods. Sixteen asymptomatic patients 10 ± 4 days after first Q wave anterior wall MI with persistent left anterior descending coronary artery occlusion and infarct-zone akinesi were randomized to immediate (2 weeks) or delayed (3 months) angioplasty. Repeat catheterization and cardiac magnetic resonance imaging (MRI) were performed after 3 and 12 months. Results. Angiography 3 months after MI revealed that LV ejection fraction (LVEF) had increased ([mean ± SD] 54.4 ± 4.3% vs. 63.9 ± 7.4%, p < 0.01) as result of improved regional function (p < 0.01) and LV end-systolic volume had decreased (p < 0.002), whereas LV end-diastolic volume remained unchanged. With delayed angioplasty, LVEF, infarct zone wall motion and LV volumes did not improve. Cardiac MRI at baseline and at 3 and 12 months confirmed these findings and extended them up to 1 year, indicating that delayed angioplasty could no longer improve LV function because of marked LV dilation (p < 0.01). Immediate angioplasty had high success rate, but restenosis (50%) was accompanied by new severe angin as clinical indicator of salvaged myocardium, which did not occur after delayed angioplasty. Conclusions. This pilot study in selected patients supports the hypothesis that myocardial viability persists (“hibernation”) for 2 to 3 weeks but not for 3 months after MI, during which time it may be worthwhile to restore blood flow to large myocardial territory, even in asymptomatic patients, to improve long-term LV function.