No change in B-type natriuretic peptide levels assessed in the late postoperative period in patients with severe mitral regurgitation after mitral valve surgery.

The impact of mitral valve (MV) surgery on levels of B-type natriuretic peptide (BNP) postoperatively has not been clearly evaluated. The aim of this study was to assess whether BNP levels decrease three to six months after MV surgery in patients with severe mitral regurgitation (MR). We prospectively enrolled patients who were referred for MV surgery with severe MR. BNP levels were measured prior to and after surgery. The mean age was 61.3 ± 13.6 years; 75% were male (n = 52). There was no difference between the mean preoperative and postoperative BNP (242.9 ± 280.3 pg/ml, 290.8 ± 549.8 pg/ml, P = 0.45) obtained at a mean of 138.7 ± 33.5 days with the bias-corrected bootstrapped 95% confidence intervals, 117.6-321.8 pg/ml and 185.4-483.8 pg/ml, respectively. Postoperative BNP tended to increase as the amount of MR increased (no MR: 212.7 ± 197.5 pg/ml, 1+MR: 592.9 ± 1174.9 pg/ml, 2+MR: 133.6 ± 121.6 pg/ml, 3+MR: 547.7 ± 332.0 pg/ml; P < 0.0001). A mild inverse correlation was noted with postoperative BNP and postoperative ejection fraction (r = -0.2596). A decrease in the ejection fraction was noted after surgery (51.7 ± 11.1%, 56.3 ± 9.6%; P = 0.03). Our findings contradict an intuitive thought that BNP levels should decrease after MV surgery for MR.