NT-proBNP for Pulmonologists: Not Only a Rule-Out Test for Systolic Heart Failure but Also a Global Marker of Heart Disease

BACKGROUND: Recognizing heart disease is relevant to pulmonologists because many patients suspected to have dyspnea of pulmonary origin harbor heart disease. OBJECTIVES: To investigate the role of N-terminal pro-brain natriuretric peptide (NT-proBNP) in identifying heart disease and cardiac causes of dyspnea among patients referred for evaluation by a pulmonologist. METHODS: 697 consecutive outpatients (aged 57.5 +/- 16.4 years) with chronic dyspnea prospectively underwent a diagnostic work-up for heart and lung diseases. RESULTS: The prevalence of patients with heart disease was 25.3%. The cardiac findings were placed into 6 groups which were associated with an increase in NT-proBNP in the following order: (1) left ventricular hypertrophy [regression coefficient (beta) = 0.33, p = 0.03]; (2) exercise-induced myocardial ischemia (beta = 0.73, p = 0.02);(3) valvular or congenital heart disease or pericardial effusion (beta = 0.93, p < 0.0001); (4) pulmonary hypertension (beta = 1.14, p < 0.0001); (5) atrial fibrillation or left bundle branch block (beta = 1.22, p < 0.0001), and (6) left ventricular systolic dysfunction (beta = 1.94, p < 0.0001). Using predefined cut-off values of 93 pg/ml (men) and 144 pg/ml (women), sensitivity was 0.75 and specificity was 0.79 for identifying heart disease. The negative predictive value was 0.90. If heart disease had to be considered as a cause of the dyspnea, sensitivity and the negative predictive value went up to 0.90 and 0.97, respectively. CONCLUSIONS: NT-proBNP performs well as a test for ruling out cardiac dyspnea. It is also useful as a rule-in test for heart disease, which enables the pulmonologist to appropriately select candidates for in-depth evaluation by cardiology.