Erythrocyte EPA, STEMI, infarct size and ventricle function
Eicosapentaenoic acid (EPA), an omega-3 fatty acid, is easily incorporated into cardiomyocyte membranes, partially displacing arachidonic acid (AA), an omega-6 fatty acid. While AA is a pro-inflammatory eicosanoid precursor, EPA release from the membranes generates anti-inflammatory lipid mediators, which contribute to the infarct-limiting effect observed in animal experimental models.
In this observational study, the proportions of EPA and AA and the AA:EPA ratio in erythrocyte membranes, a valid estimate of their proportion in cardiomyocyte membrane, were quantified in a group of 100 patients with reperfusion therapy after ST-segment elevation myocardial infarction (STEMI), on admission. They underwent an MRI scan in the acute phase (one week post STEMI) and another at six months. Infarct size and heart function (left ventricle ejection fraction (LVEF)) were also assessed. The AA:EPA ratio was directly related to the infarct size (p = 0.008) and inversely related to long-term LVEF (p = 0.012). EPA was inversely related to infarct size (p = 0.009) and directly related to long-term LVEF (p = 0.036).
In other words, a low AA:EPA ratio in the erythrocyte membrane at the time of the STEMI is associated with a smaller infarct size and long-term preservation of ventricle function.