Effect of ischemic postconditioning on myocardial salvage in patients undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction: cardiac magnetic resonance substudy of the POST randomized trial

In the effects of postconditioning on myocardial reperfusion in patients with ST-segment elevation myocardial infarction (POST) trial, ischemic postconditioning did not improve myocardial reperfusion in 700 patients with STEMI undergoing primary PCI. However, the impact of postconditioning on myocardial salvage and infarct size still needs to be addressed. The aim of this study was to investigate the effect of ischemic postconditioning on myocardial salvage using cardiac magnetic resonance (CMR) in patients with STEMI undergoing primary PCI. For the CMR substudy, a total of 111 patients was analyzed, 56 in the postconditioning group and 55 undergoing conventional primary PCI in the control group. Postconditioning was performed immediately after restoration of coronary flow by four cycles of 1-min balloon occlusion separated by 1 min of deflation. The primary end point was myocardial salvage measured by CMR 3 days after the index event. The myocardial salvage index was not improved by ischemic postconditioning compared with conventional PCI (46.3 ± 18.5 vs. 45.7 ± 20.5 %, p = 0.86). The infarct size was not significantly different between the two groups (18.8 ± 10.3 vs. 20.2 ± 11.0 %, p = 0.52). Moreover, there was no significant difference in the rates of microvascular obstruction or hemorrhagic infarction between the groups. CMR study demonstrated that ischemic postconditioning during primary PCI in STEMI patients did not improve myocardial salvage or reduce infarct size. These findings further support the results of the POST trial which showed no benefit of ischemic postconditioning as an adjunctive treatment of primary PCI.