Torrential mitral regurgitation following right ventricular apical pacing in rheumatic mitral valve disease: a case report

Background: Mitral regurgitation may develop or worsen following right ventricular apical pacing due to dyssynchronous left ventricular contraction. Pre-existing secondary mitral annular dilation is a well-recognized and important contributing factor. This description of pacing-induced torrential mitral regurgitation in the setting of rheumatic mitral valve disease is a rare case in which a primary mitral valve lesion was the antecedent mechanism. Case summary: A 60-year-old man was admitted with dizziness and pre-syncope. Twelve-lead electrocardiogram showed complete heart block. A dual-chamber pacemaker was implanted and programmed in DDD mode. Transthoracic echocardiography performed a day later demonstrated a left ventricular ejection fraction (LVEF) of 63% and moderate mitral regurgitation. The patient presented 4 months later with breathlessness and orthopnoea. Pacemaker interrogation demonstrated a 98% right ventricular pacing burden. Echocardiography revealed torrential mitral regurgitation secondary to left ventricular dyssynchrony and complete loss of leaflet coaptation with preserved systolic function. Post-capillary pulmonary hypertension was diagnosed following right heart catheterization. The patient underwent metallic mitral valve replacement, tricuspid annuloplasty, and left internal mammary artery grafting to the left anterior descending artery for a severe proximal stenosis. On inspection, the native mitral valve was notably rheumatic in appearance, and this was confirmed histologically. Discussion: It is important to closely monitor the progression of mitral regurgitation in those with primary mitral valve disease undergoing right ventricular pacing. Early follow-up may prevent the adverse haemodynamic consequences of worsening mitral regurgitation, with a greater chance of recovery of left ventricular function following surgery.