Post-conditioning reduces infarct size and edema in patients with ST-segment elevation myocardial infarction

Objectives: This study aimed to determine whether post-conditioning at the time of percutaneous coronary intervention could reduce reperfusion-induced myocardial edema in patients with acute ST-segment elevation myocardial infarction (STEMI).

Background: Myocardial edema is a reperfusion injury with potentially severe consequences. Post-conditioning is a cardioprotective therapy that reduces infarct size after reperfusion, but no previous studies have analyzed the impact of this strategy on reperfusion-induced myocardial edema in humans.

Methods: Fifty patients with STEMI were randomly assigned to either a control or post-conditioned group. Cardiac magnetic resonance imaging was performed within 48 to 72 h after admission. Myocardial edema was measured by T2-weighted sequences, and infarct size was determined by late gadolinium enhancement sequences and creatine kinase release.

Results: The post-conditioned and control groups were similar with respect to ischemia time, the size of the area at risk, and the ejection fraction before percutaneous coronary intervention. As expected, post-conditioning was associated with smaller infarct size (13 ± 7 g/m(2) vs. 21 ± 14 g/m(2); p = 0.01) and creatine kinase peak serum level (median [interquartile range]: 1,695 [1,118 to 3,692] IU/l vs. 3,505 [2,307 to 4,929] IU/l; p = 0.003). At reperfusion, the extent of myocardial edema was significantly reduced in the post-conditioned group as compared with the control group (23 ± 16 g/m(2) vs. 34 ± 18 g/m(2); p = 0.03); the relative increase in T2W signal intensity was also significantly lower (p = 0.02). This protective effect was confirmed after adjustment for the size of the area at risk.

Conclusions: This randomized study demonstrated that post-conditioning reduced infarct size and edema in patients with reperfused STEMI.