Additive prognostic values of NT-proBNP and exercise stress echocardiography in asymptomatic patients with degenerative mitral regurgitation and preserved left ventricular ejection fraction.

BACKGROUND: Exercise stress echocardiography (ESE) can be used to identify left ventricular (LV) dysfunction in asymptomatic chronic MR. NT-proBNP is the best marker for monitoring LV dysfunction.

OBJECTIVE: The aim of this study was to estimate the complementary prognostic value of ESE and NT-proBNP in asymptomatic degenerative MR with preserved LV ejection fraction (EF).

METHODS: Symptom-limited treadmill ESE was performed in 114 asymptomatic with significant degenerative MR (ERO >20mm, RV >30ml), LV end-systolic diameter <40mm and preserved LV function (EF >60%). Post-exercise EF increase of >4% was defined as contractile reserve (CR)+.

RESULTS: MV operation was performed in 19 (16.7%) and new-onset LV systolic dysfunction was developed in 23 (20.2%) patients over 3.5±1.5years. Based on ROC curve analysis, a NT-pro BNP of 100 was deemed the most relevant cutoff value to predict primary outcome with Youden's index=131.84. In sequential Cox models, a model based on clinical data and resting echocardiography variables (χ(2)=6.87) was improved by NT-proBNP (χ(2)=13.9) and presence of CR in ESE (χ(2)=20.8; p=0.0002).

CONCLUSIONS: In asymptomatic moderate to severe or severe degenerative MR and preserved LVEF, the presence of CR in ESE and NT-proBNP provide important incremental clinical determinants. In particular, the prognosis is markedly poor for those with high NT-proBNP but with absence of CR than low NT-proBNP with presence of CR.