Abstract
Interrupting myocardial reperfusion with intermittent episodes of ischemia (i.e., postconditioning) during primary percutaneous coronary intervention (PPCI) has been suggested to protect myocardium in ST-segment elevation myocardial infarction (STEMI). Nevertheless, trials provide inconsistent results and any advantage in long-term outcomes remains elusive. Using a retrospective study design, we evaluated the impact of balloon inflations during PPCI on enzymatic infarct size (IS) and long-term outcomes. We included 634 first-time STEMI patients undergoing PPCI with an occluded infarct-related artery and adequate reperfusion thereafter and divided these into: patients receiving 1-3 inflations in the infarct-related artery [considered minimum for patency/stent placement (controls); n = 398] versus ≥4 [average cycles in clinical protocols (postconditioning analogue); n = 236]. IS, assessed by peak creatine kinase, was lower in the postconditioning analogue group compared with controls [median (interquartile range) 1,287 (770-2,498) vs. 1,626 (811-3,057) UI/L; p = 0.02], corresponding to a 21 % IS reduction. This effect may be more pronounced in women, patients without diabetes/hypercholesterolemia, patients presenting within 3-6 h or with first balloon re-occlusion ≤1 min. No differences were observed in 4-year mortality or MACCE between groups. Four or more inflations during PPCI reduced enzymatic IS in STEMI patients under well-defined conditions, but did not translate into improved long-term outcomes in the present study. Large-scale randomized trials following strict postconditioning protocols are needed to clarify this effect.