Ischemic postconditioning reduces infarct size and microvascular obstruction zone in acute ST-elevation myocardial infarction – a randomized study

Introduction
Ischemic postconditiong (postcon) has been reported to reduce infarct size in ST-segment myocardial infarction (STEMI). However, recently a few other studies did not show any effect of postcon or suggested that it may even be harmful.

Aim
We sought to assess whether postcon could reduce infarct size (IS) and the microvascular obstruction (MVO) zone in early presenters with STEMI.

Material and methods
Seventy-four STEMI patients treated with primary coronary intervention (PCI) < 4 h from symptoms onset were randomly assigned to the postcon group (n = 37) or standard PCI group (n = 37). Postcon was performed immediately after obtaining reperfusion with 4 balloon occlusions, each lasting 60 s, followed by 60 seconds of reperfusion. Cardiac magnetic resonance was performed in all subjects within 48 to 96 h after admission. To evaluate the infarct size and MVO, the late gadolinium enhancement (LGE) technique was used. Infarct size was defined as an area greater than 50% of the maximal signal intensity within LGE. MVO was defined as the area of the absence or hypoenhancement of contrast surrounded by LGE. Infarct size and MVO were determined by planimetry and the summation of discs method.

Results
Postcon was associated with significantly smaller IS (16.42 ±9.6 vs. 31.2 ±22.2 g; p = 0.007) and higher ejection fraction (59.8 ±9.2% vs. 52.3 ±10.2%). The extent of MVO was significantly lower in the postcon group in comparison to the control group (0.76 ±1.4 g vs. 2.2 ±3.2 g; p = 0.03).

Conclusions
In early presenters with STEMI postcon could significantly reduce infarct size and limit reperfusion injury.