The role of myocardial viability in deriving benefit from reestablishing infarct-related artery flow after acute myocardial infarction

Early, sustained patency of the infarct-related artery (IRA) induces myocardial salvage, which preserves left ventricular (LV) function and mediates better long-term outcome. However, the time course and the mechanisms of muscle recovery after myocardial infarction are not completely understood. A large body of evidence suggests that most of the improvement occurs during the hospital phase and is related to early and sustained thrombolysis in myocardial infarction 3 flow in the IRA. Nevertheless, the relationship between IRA status and regional and global LV mechanics in the chronic phase of the disease remains controversial. Some late recovery may occur, either spontaneously or after revascularization, even in the absence of documented myocardial ischemia. The interplay between vessel patency, coronary flow grade and severity of the residual stenosis, and the presence of stunned or hibernating myocardium in the area at jeopardy may explain this delayed improvement. Although there seems to be a limited time window in which myocardium can be salvaged, timely testing for viability, particularly in patients with poor LV function, is justified even in a later phase of the disease to challenge potential cardiac recovery. Copyright (C) 2000 W.B. Saunders Company.