Mirabegron, a Clinically Approved β3 Adrenergic Receptor Agonist, Does Not Reduce Infarct Size in a Swine Model of Reperfused Myocardial Infarction

The administration of the selective beta 3 adrenergic receptor (beta 3AR) agonist BRL-37344 protects from myocardial ischemia/reperfusion injury (IRI), although the lack of clinical approval limits its translatability. We tested the cardioprotective effect of mirabegron, the first-in-class beta 3AR agonist approved for human use. A dose-response study was conducted in 6 pigs to select the highest intravenous dose of mirabegron without significant detrimental hemodynamic effect. Subsequently, closed chest anterior myocardial infarction (45 min ischemia followed by reperfusion) was performed in 26 pigs which randomly received either mirabegron (10 mu g/kg) or placebo 5 min before reperfusion. Day-7 cardiac magnetic resonance (CMR) showed no differences in infarct size (35.0 +/- 2.0% of left ventricle (LV) vs. 35.9 +/- 2.4% in mirabegron and placebo respectively, p = 0.782) or LV ejection fraction (36.3 +/- 1.1 vs. 34.6 +/- 1.9%, p = 0.430). Consistent results were obtained on day-45 CMR. In conclusion, the intravenous administration of the clinically available selective beta 3AR agonist mirabegron does not reduce infarct size in a swine model of IRI.