IDO2 and myocardial infarction: Preclinical data suggest kynurenine pathway metabolism may have cardiac-specific effects: in mice, simulation of myocardial infarction (MI) by left coronary ligation induces generation of kynurenine via indoleamine 2, 3-dioxygenase (IDO), an enzyme that catalyzes conversion of tryptophan to kynurenine (23).