Microvascular integrity after reperfusion therapy.

Several perfusion techniques have definitively shown that microvascular dysfunction plays a crucial role in patients with acute myocardial infarction. In those patients, despite a rapid and sustained restoration of flow throughout a previously occluded epicardial coronary artery, microvascular damage still may be observed. Duration of ischemia and/or time to recanalization are the most powerful determinants of microvascular dysfunction. However, the amount of tissue perfusion in infarcted patients is dependent on many other complex interrelated factors including extent of collateral circulation before recanalization, residual stenosis severity of the culprit artery, vasodilator reserve in the infarct territory, extent of reperfusion injury, and loading conditions. Because microvascular dysfunction is associated with progressive left ventricular dilation and a high frequency of postinfarction complications, all of the efforts to improve the relation between coronary reflow and microvascular perfusion are justified.