Long-term benefit of postconditioning

Background- We previously demonstrated that ischemic postconditioning decreases creatine kinase release, a surrogate marker for infarct size, in patients with acute myocardial infarction. Our objective was to determine whether ischemic postconditioning could afford (1) a persistent infarct size limitation and (2) an improved recovery of myocardial contractile function several months after infarction. Methods and Results- Patients presenting within 6 hours of the onset of chest pain, with suspicion for a first ST-segment-elevation myocardial infarction, and for whom the clinical decision was made to treat with percutaneous coronary intervention, were eligible for enrollment. After reperfusion by direct stenting, 38 patients were randomly assigned to a control (no intervention; n = 21) or postconditioned group (repeated inflation and deflation of the angioplasty balloon; n = 17). Infarct size was assessed both by cardiac enzyme release during early reperfusion and by (201)thallium single photon emission computed tomography at 6 months after acute myocardial infarction. At 1 year, global and regional contractile function was evaluated by echocardiography. At 6 months after acute myocardial infarction, single photon emission computed tomography rest-redistribution index (a surrogate for infarct size) averaged 11.8 +/- 10.3% versus 19.5 +/- 13.3% in the postconditioned versus control group (P = 0.04), in agreement with the significant reduction in creatine kinase and troponin I release observed in the postconditioned versus control group (-40% and -47%, respectively). At 1 year, the postconditioned group exhibited a 7% increase in left ventricular ejection fraction compared with control (P = 0.04). Conclusions- Postconditioning affords persistent infarct size reduction and improves long-term functional recovery in patients with acute myocardial infarction.