Utility of BNP in Differentiating Constrictive Pericarditis from Restrictive Cardiomyopathy in Patients with Renal Insufficiency

BackgroundDifferentiating between constrictive pericarditis (CP) and restrictive cardiomyopathy (RCMP) is difficult because of similar clinical and hemodynamic presentation. Brain natriuretic peptide (BNP) has been reported a useful noninvasive biomarker to differentiate CP from RCMP; however, its utility in patients with renal insufficiency has not been evaluated.Methods and ResultsConsecutive patients with suspected CP or RCMP were enrolled. All but 7 patients underwent transseptal catheterization. BNP, renal function, and comorbid conditions were recorded at the time of the procedure. Renal function was estimated using the Cockcroft-Gault formula. Descriptive statistics, Student t-test, and Mann-Whitney U test were performed; P < .05 was significant. Twenty-two patients had hemodynamically or surgically proven CP or RC. In patients with CP, 9 had at least Stage II kidney disease (GFR <90 mL/min, mean 58) and 8 had normal or Stage I kidney disease (GFR >90 mL/min, mean 118). BNP was higher in patients with CP and renal insufficiency versus those with CP and normal renal function (433 versus 116 pg/mL; P = .016). BNP in patients with CP and normal renal function was lower than in patients with RC (116 versus 728 pg/mL; P = .005).ConclusionBNP has reduced clinical utility in renal insufficiency to differentiate CP from RCMP.