The efficacy of brain natriuretic peptide levels in differentiating constrictive pericarditis from restrictive cardiomyopathy.

OBJECTIVES We sought to determine the usefulness of brain natriuretic peptide (BNP) measurements to differentiate constrictive pericarditis (CP) from restrictive cardiomyopathy (RCMP). BACKGROUND The differentiation of CP from RCMP may be clinically difficult and often requires hemodynamic assessment. No laboratory marker has been shown to differentiate the two conditions. METHODS We measured BNP levels in 11 patients suspected of having either CP or RCMP. All patients had hemodynamic assessment the day of BNP measurements. RESULTS Six patients had CP and five patients had RCMP based on established hemodynamic criteria. Both CP and RCMP patients had similar elevation in intracardiac pressures. Despite similar pressures, the mean plasma BNP levels were significantly higher in RCMP compared to CP (825.8 +/- 172.2 pg/ml vs. 128.0 +/- 52.7 pg/ml, p < 0.001, respectively). CONCLUSIONS The BNP levels are significantly elevated in RCMP compared to CP patients; BNP may prove to be a useful noninvasive marker for the differentiation of the two conditions.