Symptoms of pulmonary hypertension are unspecific and diagnosis is often delayed. This prospective and consecutive study investigated the role of N-terminal pro-brain natriuretic peptide (NT-proBNP) for detecting patients with pulmonary hypertension among those referred for pulmonologist evaluation of chronic dyspnea.
A total of 697 outpatients (age 57.5 ± 6.4 years) with dyspnea of at least 2 weeks duration underwent a comprehensive diagnostic work-up for heart and lung disease including Doppler echocardiography. Pulmonary hypertension was diagnosed if the peak systolic pressure gradient across the tricuspid valve (Δp) was ≥ 35 mmHg. Borderline Δps (30–34 mmHg) were also recorded. Multiple regression analysis was used to evaluate the relation between NT-proBNP and Δp with adjustment for important extracardiac covariates such as age, sex and body mass index. In patients with heart disease, the model was additionally adjusted for the following findings: (a) impaired left ventricular systolic function (30 patients), (b) atrial fibrillation (51 patients), (c) significant valvular or congenital heart disease (26 patients), (d) exercise-induced myocardial ischemia (12 patients) and (e) left ventricular hypertrophy (66 patients).
Pulmonary hypertension was found in 61 patients. Borderline Δps were present in 21 subjects. There was a strong association between NT-proBNP and Δp after adjustment for the above-mentioned extracardiac covariates and the type of heart disease (regression coefficient 0.04 [95%-CI 0.03; 0.06], p < 0.0001). The impact of Δp on NT-proBNP was second only to those of impaired left ventricular function and atrial fibrillation. Using a predefined NT-proBNP cut-off value of 100 pg/ml, only 8 out of the 61 patients with pulmonary hypertension were missed. These patients invariably had mild disease with Δps < 45 mmHg.
NT-proBNP increases with the severity of pulmonary hypertension independently of coexistent left heart disease. A gender-independent NT-proBNP cut-off value of 100 pg/ml may be useful to the pulmonologist for ruling out moderate and severe pulmonary hypertension.
Elevated NT-proBNP levels help in the early diagnosis of pulmonary hypertension, if these patients are referred for in-depth evaluation by cardiology.
Siegfried Wieshammer, No Financial Disclosure Information; No Product/Research Disclosure Information