Imaging post-reperfusion metabolism in porcine myocardial infarction with hyperpolarized ¹³C pyruvate MRI

Reperfusion injury after primary percutaneous coronary intervention is a potential target for improving treatment of myocardial infarction. Reperfusion represents a sudden metabolic challenge of the ischemic myocardial tissue, which is thought to be a driver of reperfusion injury that is difficult to evaluate with current technologies.

We investigated the use of metabolic magnetic resonance imaging with hyperpolarized [1-¹³C]pyruvate for investigation of post-reperfusion metabolism in a pig model of acute myocardial infarction. To induce ischemia, 15 pigs had a coronary balloon placed in the left anterior descendent for one hour. Seven animals underwent mechanical preload reduction in effort to investigate the effects of increased salvage. After three hours of reperfusion, the animals were scanned with hyperpolarized [1-¹³C]pyruvate MRI to image the balance between mitochondrial and glycolytic metabolism.

Larger conversion from [1-¹³C]pyruvate to [1-¹³C]lactate, representing glycolytic metabolism, was observed in the area-at-risk (P <.001). Similar, but non-significant, hypermetabolism was observed for conversion of [1-¹³C]pyruvate to [¹³C]bicarbonate (P =.07), representing mitochondrial metabolism. Conversion from [1-¹³C]pyruvate to [1-¹³C]alanine seemed to decrease in the group with preload reduction but increase in the sham group. The observed hypermetabolism correlated with the amount of salvaged myocardium (r =.7, P <.01), but not with the size of the area-at-risk.

This study shows that the salvaged myocardium becomes hypermetabolic and glycolytic after reperfusion, and that a metabolic MRI may be a valuable tool in attempts to modulate post-reperfusion metabolism in preclinical and clinical research alike.