Prognostic Implications of Point-of-Care and Serial B-type Natriuretic Peptide Levels in Patients With Hypertrophic Cardiomyopathy

Abstract

Hypertrophic cardiomyopathy (HC) is a heterogenous disease with a variable clinical course. Predictors of long-term adverse cardiovascular events are needed. Our objectives were to determine the long-term prognostic value of a single and serial point of care (POC) B-type natriuretic-peptide (BNP) measurements in HC. One hundred and eleven ambulatory patients with HC (mean age 53 ± 16 years) were prospectively recruited over a 2-year period (2004 to 2006). A clinical assessment, comprehensive echocardiogram, and a POC BNP level was obtained at baseline and at a 1- to 2-year follow-up. They were subsequently followed for the occurrence of major adverse cardiac events (MACE). The median baseline BNP concentration was 114 pg/ml (range 5.3 to 1550 pg/ml). During a mean follow-up of 6.2 ± 3.4 years, 42 patients (38%) had a MACE. In a multivariable Cox model including clinical and echocardiographic predictors, logBNP (HR 4.30; 95% confidence interval 1.97 to 9.37, p <0.001) and left ventricualr ejection fraction (LVEF) (HR 0.96; 95% confidence interval 0.94 to 0.99, p = 0.011) remained significant predictors of MACE. Nested models demonstrated incremental prognostic value of logBNP for MACE (chi-square increased from 4.3 to 22.8, p <0.01) over clinical and echocardiographic factors. Patients with persistently elevated BNP (>100 pg/ml) at baseline and at the second visit were at a higher risk of developing MACE during follow-up (5-year MACE-free survival of 0.91 (SE 0.06) vs 0.45 (SE 0.09), p <0.001). In conclusion, POC BNP levels in patients with HC were predictive of long-term MACE and had independent and incremental value. Patients with persistently elevated BNP levels were at a higher risk of MACE.