B-type natriuretic peptide predicts disease severity in children with hypertrophic cardiomyopathy.

BACKGROUND

In adults with hypertrophic cardiomyopathy (HCM), plasma B-type natriuretic peptide (BNP) levels correlate with dyspnoea class and other markers of disease severity. In children with HCM, symptoms are a poor guide to disease severity and no studies have evaluated the clinical utility of BNP testing.

OBJECTIVE

To assess the relation of BNP levels to symptoms and markers of disease severity in children with HCM.

METHODS

Forty-four consecutive patients with HCM (27 male, age <or=17 years (median 13.6) underwent assessment of plasma BNP. Clinical evaluation of patients was carried out, including ECG, echocardiography and tissue Doppler imaging.

RESULTS

BNP levels correlated with maximal left ventricular (LV) wall thickness (r(s) = 0.631, p<0.001), resting LV outflow tract gradient (r(s) = 0.611, p<0.001), transmitral E/septal Ea (E/Ea(s)) ratio (r(s) = 0.770, p<0.001) and percentage predicted maximum VO(2) (r(s) = -0.390, p = 0.025); there was no relation between BNP and heart failure symptoms. BNP levels were higher in patients who had undergone implantation of an internal cardioverter-defibrillator than in those who had not (309 (interquartile range (IQR) 181-391) vs 50 (IQR 18-188) pg/ml, p = 0.001). BNP was independently associated with E/Ea(s) (r(s) = 0.632, p<0.001) and maximal LV wall thickness (r(s) = 0.412, p = 0.008) on multivariate analysis. At a cut-off point of 50 pg/ml, BNP had a positive predictive value of 93% and a negative predictive value of 80% for predicting E/Ea(s) >10 (area under the receiver operator characteristic curve = 0.875 (p<0.001)).

CONCLUSIONS

BNP levels correlate with non-invasive parameters of disease severity in children with HCM, including measures of raised LV filling pressures. For patients in whom evaluation of symptoms is difficult, BNP may be a useful additional tool in the assessment of disease severity.