Risk factors and outcomes with surgical bioprosthetic mitral valve dysfunction

BACKGROUND: There are insufficient data regarding the risk factors associated with valve dysfunction of bioprosthetic valves in the mitral position This study aimed to investigate the factors associated with bioprosthetic mitral valve (MV) dysfunction (MVD). METHODS: A total of 245 patients (age 67.2±11.2 years, 74.9% women) who were followed up for more than 5 years after surgical bioprosthetic MV replacement were analysed in the setting of retrospective study design. MVD was defined as an increased mean gradient of >5 mm Hg with limited leaflet motion and/or newly developed MV regurgitation of at least moderate severity on follow-up echocardiography. The clinical outcome was defined as a composite of cardiovascular mortality, redo MV surgery or intervention and heart failure-related hospitalisations. RESULTS: During a median of 96.0 months (IQR 67.0-125.0 months), bioprosthetic MVD occurred in 66 (27.6%) patients. Factors associated with bioprosthetic MVD detected by multivariate regression analysis were age at surgery (HR 0.98, 95% CI 0.96 to 0.99, p<0.001), chronic kidney disease (HR 3.27, 95% CI 1.74 to 6.12, p<0.001), elevated mean diastolic pressure gradient >5.5 mm Hg across the bioprosthetic MV early after operation (HR 2.02, 95% CI 1.08 to 3.78, p=0.028) and average haemoglobin level after surgery (HR 0.80, 95% CI 0.67 to 0.96, p=0.015). Patients with bioprosthetic MVD showed significantly poorer clinical outcomes than those without bioprosthetic MVD (log-rank p<0.001). CONCLUSIONS: Young age at operation, chronic kidney disease, elevated pressure gradient across the bioprosthetic MV early after surgery and postsurgical anaemia are associated with bioprosthetic MVD. Bioprosthetic MVD is associated with poor clinical outcomes.