Reduction of myocardial reperfusion injury by high-dose beta-blockade with esmolol

BACKGROUND: Myocardial ischemia reperfusion injury may be reduced by beta-blockade. However, how myocardial salvage is affected when beta-blockade is limited to the reperfusion period is unknown. We investigated the impact of CPB and esmolol during reperfusion on infarct size and left ventricular function in two different experimental models of acute myocardial ischemia. METHODS: In open-chest dogs, myocardial ischemia was induced by LAD occlusion in both studies. In study 1, infarct size (TTZ stain) and myocardial water content (MWC, microgravimetry) were determined, comparing reperfusion with blood and esmolol to blood without additives. Study 2 investigated the impact of esmolol on LV function (sonomicrometry, echocardiography) and MWC (microgravimetry) compared to warm blood cardioplegia in a more clinically oriented model. RESULTS: Infarct size and MWC in reperfused myocardium were significantly reduced by esmolol during reperfusion. Global LV function was better preserved in the esmolol group, whereas no difference was seen regarding regional function. CONCLUSIONS: Myocardial salvage may be significantly enhanced by CPB and esmolol, even when treatment with esmolol is initiated as late as with the onset of reperfusion.