Ischemia, reperfusion, and the role of surgery in the treatment of cardiogenic shock secondary to acute myocardial infarction: An interpretative review

Cardiogenic shock (CS) is the leading cause of death for patients hospitalized with acute myocardial infarction (AMI). Despite contemporary management of AMI, the incidence of shock due to left ventricular failure has not declined and its mortality continues to be in excess of 50%. Furthermore, the role and indications of the different means of acute revascularization remain unclear. Recent observational and randomized studies have shown improved survival in patients acutely revascularized by either percutaneous interventions or conventional surgery, particularly in patients younger than 75 years of age. Current guidelines recommend surgical revascularization in selected patients with multiple vessel disease who develop shock due to progressive ischemia of the remote myocardium up to 18 h from the onset of shock. However, patients with single-vessel disease who develop shock as a consequence of the initial infarction can only be helped if revascularization is achieved during the first 4 to 6 h after the occlusion of the infarct related artery, preferable by percutaneous techniques. Not all ischemic myocytes become irreversibly injured at the same time. Due to variability in the distribution of collateral flow, there is great variability in the severity of ischemia. Myocytes can exhibit different metabolic responses including hibernation, ischemic preconditioning, stunning, reperfusion injury, and necrosis. Precise knowledge of these biochemical and metabolic changes that take place in the myocardium after arterial occlusion and following reperfusion is paramount to the understanding of the indications for acute revascularization, the implementation of the different management strategies to enhance myocardial preservation and recovery, and the role of circulatory support in these exceedingly sick patients. (C) 2004 Elsevier Inc. All rights reserved.