Background: Reduction of infarct size by ischemic postconditioning (IPost) has been reported in smaller proof-of-concept clinical studies, but has not been confirmed in other smaller studies. The principle needs to be evaluated in larger groups of ST-elevation myocardial infarction (STEMI) patients before being implemented in clinical practice. This study assessed the effect of ischemic postcoditioning (IPost) on infarct size in patients with STEMI treated by primary percutaneous coronary intervention (PCI).
Methods and results: Patients with first-time STEMI, <6 hours from symptom onset, referred to primary PCI were randomized to IPost or control groups. IPost was administered by 4 cycles of 1-minute reocclusion and 1-minute reperfusion, starting 1 minute after opening, followed by stenting. In the control group, stenting was performed immediately after reperfusion. The primary endpoint was infarct size measured by cardiac magnetic resonance after 4 months. A total of 272 patients were randomized. Infarct size (percent of left ventricular mass) after 4 months (median values and interquartile range) was 14.4% (7.7, 24.6) and 13.5% (8.1, 19.3) in the control group and IPost group, respectively (P=0.18). No significant impact of IPost was found when controlling for baseline risk factors of infarct size in a multivariate linear regression model (P=0.16). The effects of IPost on secondary endpoints, including markers of necrosis, myocardial salvage, and ejection fraction, as well as adverse cardiac events during follow-up, were consistently neutral.
Conclusions: In contrast to several smaller trials reported previously, we found no significant effects of IPost on infarct size or secondary study outcomes.
Clinical trial registration url: http://www.clinicaltrials.gov Unique identifier: NCT.No.PO1506.
Trial registration: ClinicalTrials.gov NCT00922675.
Keywords: acute myocardial infarction; infarct size; percutaneous coronary intervention; postconditioning; reperfusion injury.