The Combination of Valsartan and Spironolactone Mitigated Mitral Regurgitation-Induced Cardiac Dysfunction in a Novel Rat Model.

Abstract: Despite its high prevalence, effective treatment for degenerative mitral regurgitation (MR) remains elusive. Although the mineralocorticoid-receptor antagonist spironolactone, in conjunction with renin-angiotensin-aldosterone system inhibitors, has been shown to reduce mortality in patients with heart failure with reduced ejection fraction, its efficacy in managing degenerative MR is uncertain. In this study, we aimed to compare the effectiveness of valsartan (a renin-angiotensin system inhibitor), spironolactone, and combination therapy in mitigating MR-induced myocardial dysfunction. Using a mini-invasive model of degenerative MR, we administered valsartan (31 mg/kg/d), spironolactone (80 mg/kg/d), or a combination of both to rats over a 4-week period. Serial echocardiography and pressure-volume loops were utilized to assess cardiac function and hemodynamics. Rats with degenerative MR treated with valsartan or spironolactone alone did not show significant improvement in myocardial dysfunction. In contrast, combination therapy resulted in significant improvement. Similarly, the pressure-volume relationship was significantly improved in rats treated with the combination therapy compared with that in rats treated with a single therapy. Mechanistically, combination therapy effectively suppressed circulating and cardiac expression of aldosterone- and apoptosis-associated proteins. Overall, combination treatment with valsartan and spironolactone significantly attenuated the degenerative MR-induced myocardial stress and dysfunction, suggesting a potential therapeutic avenue for managing degenerative MR-induced heart failure.