Reperfusion Injury and Infarct Size: Why Translation has Been Difficult, and How We Move Forward

Area of Science:

• Cardiology
• Translational Medicine
• Clinical Trial Design

Background:

• Reperfusion injury in ST-elevation myocardial infarction (STEMI) is a complex network of pathways.
• Contemporary cardioprotection trials in STEMI have yielded largely neutral results, failing to demonstrate significant infarct size reduction.
• Existing frameworks lack clinical actionability, hindering effective trial design.

Purpose of the Study:

• To identify reasons for the translational failure of cardioprotection in STEMI.
• To propose a framework for designing future, more successful cardioprotection trials.
• To re-evaluate the biological relevance versus trial design in cardioprotection research.

Main Methods:

• Review of recent scientific statements and contemporary clinical trials in STEMI cardioprotection.
• Analysis of trial outcomes, including infarct size and microvascular obstruction (MVO) via cardiovascular magnetic resonance (CMR).
• Evaluation of patient enrichment strategies and preclinical standards for clinical translation.

Main Results:

• Trials like STEMI-DTU, PiCSO-AMI-I, EURO-ICE, and COOL AMI EU showed no significant cardioprotective effects on infarct size.
• The supersaturated oxygen (SSO₂) program demonstrated progressive benefits with patient enrichment, especially in those with severe coronary microvascular dysfunction.
• Microvascular obstruction (MVO) ≥ 2.6% of left ventricular mass is a predictor of adverse outcomes in STEMI patients.

Conclusions:

• Translational failure stems from misalignment between heterogeneous STEMI biology and trial design, not biological irrelevance.
• Future trials require aligned patient selection, phenotype-specific endpoints, and adaptive architectures.
• Combining mechanical interventions with pharmacological adjuncts and employing enriched cohorts may unlock clinical benefits in STEMI cardioprotection.