Relation of B-Type Natriuretic Peptide Levels Before and After Exercise and Functional Capacity in Patients With Idiopathic Dilated Cardiomyopathy

Although much is known about the value of B-type natriuretic peptide (BNP) at rest, the significance of the responsiveness of BNP during exercise in patients with chronic heart failure (HF) without coronary artery disease remains to be established. A role of BNP release during exercise in the functional disability of patients with chronic HF and idiopathic dilated cardiomyopathy (IDC) was hypothesized. One hundred five consecutive patients with an established diagnosis of HF and IDC who underwent symptom-limited cardiopulmonary exercise testing were studied. BNP was measured immediately before exercise and within 1 minute of the end of exercise. BNP at rest increased significantly at peak exercise (median from 66.5 (first, third quartiles 18, 168) to 72.0 pg/ml (26, 208), p <0.001), but BNP response was not uniform. BNP response increased in 63% of patients, did not change in 22%, and decreased in 15%. BNP at rest and BNP response showed an inverse correlation (p <0.001, r = −0.523). Aging and low left ventricular ejection fraction were independent predictors of higher BNP levels at rest, but lower BNP response. Beta-blocker therapy did not influence BNP response. BNP at rest correlated negatively with functional capacity (p <0.001, r = −0.516), whereas BNP response correlated positively (p = 0.002, r = 0.326). Patients with BNP release (vs patients without) had higher maximum oxygen consumption (19.2 ± 5.1 vs 15.9 ± 3.6, p <0.001), better functional capacity (59 ± 13% vs 50 ± 15%, p = 0.002), and lower minute ventilation/carbon dioxide production slope (33.6 ± 4.8 vs 36.5 ± 7.7, p = 0.026) independent of other clinical parameters. In conclusion, BNP release during exercise could be a determinant of functional capacity in patients with chronic HF and IDC.