The 5-hydroxytryptamine (5-HT: or serotonin) type 2B receptor (5-HT2BR) antagonist cyproheptadine reduces 5-HT levels after myocardial infarction (MI), prevents valvular fibrotic remodeling, and is associated with a larger increase in mitral valve size and less mitral regurgitation (MR), new lab and animal data suggest.