Coronary microembolization during early reperfusion: infarct extension, but protection by ischaemic postconditioning

Area of Science:

• Cardiovascular Research
• Myocardial Infarction
• Reperfusion Injury

Background:

• Reperfusion injury impacts myocardium and coronary microcirculation after acute myocardial infarction.
• Microembolization from culprit lesions contributes to microvascular obstruction.
• Previous studies overlooked microembolization's role in ischemia/reperfusion injury and its potential as a target for postconditioning.

Purpose of the Study:

• To investigate the impact of microembolization during reperfusion on infarct size.
• To assess the efficacy of ischemic postconditioning in the presence of microembolization.

Main Methods:

• Anesthetized pigs underwent 90-minute low-flow ischemia followed by reperfusion.
• Microembolization was induced using microspheres.
• Ischemic postconditioning involved cycles of reperfusion and re-occlusion.
• Infarct size was measured using triphenyl tetrazolium chloride staining.

Main Results:

• Microembolization significantly increased infarct size (32% to 47% of area at risk).
• Embolizing particles accumulated in the infarct border, extending infarct size.
• Postconditioning reduced infarct size both with and without microembolization (21% and 26% respectively).
• Particles did not accumulate in the infarct border when postconditioning was applied with microembolization.

Conclusions:

• Microembolization during reperfusion exacerbates infarct size in myocardial infarction.
• Ischemic postconditioning remains effective in reducing infarct size and expansion, even when microembolization is present.