CMA1 and myocardial infarction: Consequently, chymase inhibition can reduce myocardial fibrosis following myocardial infarction, myocardial ischemia, and during pacing-induced cardiomyopathy in rat, mouse, and canine models, respectively.50, 51, 52 Likewise, in vitro and in vivo mouse studies have shown that tryptases directly stimulate collagen production by cardiac fibroblasts.53, 54, 55 Intracardiac expression of tryptase is increased in mice with hypertension, overload cardiomyopathy, or following viral myocarditis.53