Prospective validation of the prognostic usefulness of brain natriuretic peptide in asymptomatic patients with chronic severe mitral regurgitation.

OBJECTIVES: The purpose of the study was to determine the independent and additive prognostic value of brain natriuretic peptide (BNP) in patients with severe asymptomatic mitral regurgitation and normal left ventricular function.

BACKGROUND: Early surgery could be advisable in selected patients with chronic severe mitral regurgitation, but there are no criteria to identify candidates who could benefit from this strategy. Assessment of BNP has not been studied in asymptomatic patients with severe mitral regurgitation; hence, its prognostic value remains unclear.

METHODS: We prospectively evaluated 269 consecutive patients with severe asymptomatic organic mitral regurgitation and left ventricular ejection fraction above 60%. The first 167 consecutive patients served as the derivation cohort, and the following 102 patients served as a validation cohort. The combined end point was the occurrence of either symptoms of congestive heart failure, left ventricular dysfunction, or death at follow-up.

RESULTS: The end point was reached in 35 (21%) patients of the derivation set and in 21 (20.6%) patients of the validation cohort. The receiver-operating characteristics curve yielded an optimal cutoff point of 105 pg/ml of BNP that was able to discriminate patients at higher risk in both cohorts (76% vs. 5.4% and 66% vs. 4.0%, respectively). In both sets, BNP was the strongest independent predictor by multivariate analysis.

CONCLUSIONS: Among patients with severe asymptomatic organic mitral regurgitation, BNP > or =105 pg/ml discriminates a subgroup of patients at higher risk. Because of its incremental prognostic value, BNP assessment should be considered in clinical routine workup for risk stratification.