Effect of ischemic postconditioning on microvascular obstruction in reperfused myocardial infarction. Results of a randomized study in patients and of an experimental model in swine

Abstract

Background: Ischemic postconditioning (PCON) appears as a potentially beneficial tool in ST-segment elevation myocardial infarction (STEMI). We evaluated the effect of PCON on microvascular obstruction (MVO) in STEMI patients and in an experimental swine model.

Methods: A prospective randomized study in patients and an experimental study in swine were carried out in two university hospitals in Spain. 101 consecutive STEMI patients were randomized to undergo primary angio-plasty followed by PCON or primary angioplasty alone (non-PCON). Using late gadolinium enhancement cardiovascular magnetic resonance, infarct size and MVO were quantified (% of left ventricular mass). In swine, using an angioplasty balloon-induced anterior STEMI model, MVO was defined as the % of area at risk without thioflavin-S staining.

Results: In patients, PCON (n = 49) in comparison with non-PCON (n = 52) did not significantly reduce MVO (0 [0-1.02]% vs. 0 [0-2.1]% p = 0.2) or IS (18 +/- 13% vs. 21 +/- 14%, p = 0.2). MVO (>1 segment in the 17-segment model) occurred in 12/49 (25%) PCON and in 18/52 (35%) non-PCON patients, p = 0.3. No significant differences were observed between PCON and non-PCON patients in left ventricular volumes, ejection fraction or the extent of hemorrhage. In the swine model, MVO occurred in 4/6 (67%) PCON and in 4/6 (67%) non-PCON pigs, p = 0.9. The extent of MVO (10 +/- 7% vs. 10 +/- 8%, p = 0.9) and infarct size (23 +/- 14% vs. 24 +/- 10%, p = 0.8) was not reduced in PCON compared with non-PCON pigs.

Conclusions: Ischemic postconditioning does not significantly reduce microvascular obstruction in ST-segment elevation myocardial infarction.