B-Type Natriuretic Peptide in Isolated Severe Tricuspid Regurgitation: Determinants and Impact on Outcome

Background: The plasma B-type natriuretic peptide (BNP) level is a useful prognostic marker in heart failure and valvular heart disease. In patients with isolated severe tricuspid regurgitation (TR), little is known about the determinants of plasma BNP levels and the correlation with future outcome. The purpose of this study was to identify the determinants of plasma BNP levels in patients with isolated severe TR and the value of the BNP level in predicting postoperative outcomes after corrective surgery. Methods:We prospectively enrolled 39 patients with isolated, severe TR undergoing corrective surgery. A plasma BNP assay and cardiac magnetic resonance (CMR) imaging were performed before surgery. The combined end-point was the occurrence of cardiac death or readmission due to heart failure. Results: Linear regression analysis showed that the left ventricular ejection fraction and right ventricular end systolic volume were the most important determinants of the BNP levels (p = 0.002, $R^2$ = 0.315). Based on the receiver operating characteristics (ROC) curve, we were able to derive an optimal cutoff value (200 pg/mL) to predict postoperative cardiac death with a sensitivity of 80% and a specificity of 85%. The one-year survival rate was 96% in patients with a BNP < 200 pg/mL and 53% in patients with a BNP ${\geq}$ 200 pg/dL (p = 0.001). Conclusion: An elevation in the BNP level is determined by the functional status of the right and left ventricles in patients with isolated, severe TR. An elevated BNP predicts adverse events after corrective surgery. Therefore, the BNP level should be included in the clinical evaluation and risk stratification of patients with isolated TR.