Infarct-Related Artery Patency and Long-Term Effects on Left Ventricular Remodelling

Within a narrow time frame after acute myocardial infarction (AMI), spontaneous or therapeutic reperfusion can lead to myocardial salvage, preservation of left ventricular (LV) function and improved survival. However, several studies have shown that the improvement in prognosis of patients with sustained patency of the infarct-related artery (IRA) is out of proportion to the observed improvement in ventricular function. Also, patients who undergo late thrombolysis (i.e. after the traditional 4- to 6-hour time window for myocardial salvage), show improvements in LV function and prognosis. These observations suggest that other mechanisms contribute to the beneficial effects of reperfusion in addition to the salvage of ischaemic myocardium. Experimental and clinical data support the concept the late reperfusion prevents LV dilatation and improves LV function by limiting infarct expansion and ventricular remodelling. These benefits are independent of any limitation on infarct size. Ventricular remodelling is a dynamic process, starting in the acute phase with infarct expansion, and progressing to LV dilatation and hypertrophy. The remodelling process has regional and global effects on