Abstract 3837: Effect of Postconditioning on Infarct Size in Patients With ST-elevation Myocardial Infarction
Introduction: Experimental studies have demonstrated that postconditioning, reperfusion interrupted by brief repetitive cycles of re-occlusions, limits final infarct size. Earlier experiences from small clinical studies suggest that postconditioning may induce cardioprotection in patients with acute myocardial infarction.
Hypothesis: We assessed the hypothesis that postconditioning limits infarct size in patients with ST-elevation myocardial infarction (STEMI).
Methods: Seventy-six consecutive patients (age 62±1 years; male n=66) with chest pain ≥30 min and ≤6 hours, ST-elevation or left bundle branch block, no previous myocardial infarction, total occlusion (TIMI 0 flow) of the infarct related artery eligible for primary percutaneous coronary intervention (PCI) were included. The patients were randomized to standard PCI procedure (n=38) or four cycles of 60 seconds reperfusion and 60 seconds of re-occlusion (postconditioning) before permanent reperfusion (n=38). The area at risk was determined from angiographic abnormally contracting segments in relation to total left ventricular volume. Infarct size was quantified with a validated semi-automatic software from delayed enhancement magnetic resonance imaging on day 6 –9. Data are expressed as mean±SEM.
Results: Infarct size, expressed in relation to the area at risk, in the postconditioned group (45±4 %, n=38) did not differ from that of the standard PCI group (44±4 %, n=38). Similarly, infarct size in relation to left ventricular mass did not differ between the groups. Furthermore, there was no difference in infarct size between the postconditioned and standard PCI groups when anterior and inferiolateral wall infarcts were analyzed separately. Total troponin-T release during 48 hours did not differ significantly between the postconditioned and standard PCI groups (area under curve: 216±24 vs. 186±25).
Conclusion: In conclusion, this prospective randomized clinical study suggests that postconditioning, in contrast to previous findings, does not reduce early infarct size in patients with STEMI. It remains to be evaluated whether long term follow-up may reveal differences in infarct size.