Dynamic change of mitral regurgitation after myocardial reverse remodelling: a case report

BACKGROUND: Chronic mitral regurgitation can be primary (degenerative) or secondary (functional); each has its own aetiology, treatment approach, and prognosis. A combination of the two types of regurgitation can lead to unexpected haemodynamic changes. CASE SUMMARY: A 72-year-old woman presented to our hospital with dyspnoea on exertion, moist cough, and orthopnoea. At admission, transthoracic echocardiography (TTE) findings revealed severely reduced left ventricular ejection fraction, dilation of the left ventricle and left atrium, mild mitral regurgitation with prolapse of the posterior leaflet, and bilateral leaflet tethering. She was diagnosed with idiopathic cardiomyopathy with mild mitral regurgitation. After compensation of heart failure, angiotensin-receptor blocker and beta-blocker treatment were initiated, and the dose was subsequently titrated. At 7 months after initiating medical therapy, TTE showed significant improvement of the left ventricular ejection fraction, disappearance of left ventricular dilation (reverse remodelling), and mitral valve tethering. However, posterior leaflet prolapse became apparent, and mitral regurgitation blowing became more severe. Chordal lengthening, leaflet thickening, and degeneration were observed, but there were no ruptured chordae. Successful surgical repair of the mitral and tricuspid valves was performed. DISCUSSION: In this unusual mitral regurgitation case, the regurgitation worsened following an improvement of cardiac function due to the loss of tethering from a reduction of the left ventricular diameter and an increase in closing force by increasing the left ventricular contractile force. Eventually, mitral regurgitation prolapse became apparent. Therefore, we should consider that reverse remodelling may exacerbate mitral regurgitation.