Brain natriuretic peptide as a preclinical marker of chronic pulmonary hypertension in patients with pulmonary embolism

Chronic thromboembolic pulmonary hypertension (CTPH) is a potential complication of pulmonary embolism (PE). Only few studies have assessed the role of brain natriuretic peptide (BNP) in patients with chronic pulmonary hypertension, and there are no data on the potential utility of BNP as a preclinical biomarker of CTPH. To assess the correlation between pulmonary artery systolic pressures (PAPs) and amino terminal proBNP (Nt-proBNP) and its value in the diagnosis of CTPH in patients with previous PE. Patients were evaluated with echocardiography at least 6 months after the index event. Pulmonary hypertension was defined as PAPs ≥40 mmHg at rest. Each subject underwent measurement of Nt-proBNP. Forty-nine patients were enrolled (mean age 64.5 ± 13.1 years; 22 men). Seven patients had CTPH, and two were symptomatic. There was a good correlation between PAP on echocardiography and Nt-proBNP (r 0.64; P = 0.00003). Nt-proBNP was elevated in 6 of 7 patients [sensitivity: 85.7%; 95% confidence interval (CI): 48.7, 97.4] and it was normal in 35 of 42 patients without CTPH (specificity: 76.2%; 95% CI: 61.5, 86.5%). Six of the 13 patients with high Nt-proBNP levels had CTPH, whereas 1 of 36 patients with normal Nt-proBNP levels had pulmonary hypertension. The resulting positive predictive value was 46.1% (95% CI: 19.2, 74.9), and the negative predictive value was 97.2% (95% CI: 85.5–99.9). In conclusion, Nt-proBNP correlates with PAPs and may be used to exclude preclinical or symptomatic CTPH in patients with previous PE. Prospective studies on a larger population are warranted to confirm our preliminary findings.