B-type natriuretic peptide (BNP) in patients undergoing mitral valve surgery

Plasma B-type natriuretic peptide (BNP) level may be increased in patients with valvular disease. Recent studies have suggested that in patients undergoing aortic valve replacement, an increased preoperative BNP is associated with a worse operative outcome. Little is known about the perioperative value of BNP in patients undergoing mitral valve (MV) surgery. We measured the preoperative and postoperative BNP levels in this population and analyzed the impact of the increased BNP level on surgical outcome.

From March 2004 to February 2005, 42 patients (mean age 64 +/- 12 years, 18 [42%] male) were enrolled in a prospective study. All patients underwent surgery for severe mitral regurgitation. The mean ejection fraction was 49 +/- 13%, and 26 (62%) patients presented with atrial fibrillation (AF).

The median preoperative and postoperative BNP levels were 108 (9.7 to 995) and 357 (143 to 904) pg/mL, respectively (p = 0.002). Heart failure (p = 0.03), atrial fibrillation (AF) (p = 0.01), and ejection fraction (p = 0.01) were associated with an increased preoperative BNP level. In a multivariate analysis, the only independent predictor of the increased BNP level was AF (p = 0.01). In a univariate analysis, the preoperative BNP level was a significant predictor for inotropic support (p < 0.001), ventilation time (p = 0.003), intensive care unit (ICU; p = 0.01), and hospital length of stay (p = 0.02). In the multivariate analysis, BNP was not a predictor of these variables.

Preoperative plasma BNP level presents with a high individual variability in patients with MV regurgitation. AF was the only independent predictor of an increased preoperative BNP level. The preoperative BNP level was not a predictor of surgical outcome. Further studies are required to confirm these findings and evaluate the potential role of this marker for patient selection.