B-type natriuretic peptide: A 32-amino-acid polypeptide secreted by the ventricles of the heart in response to excessive stretching of myocytes (heart muscles cells) in the ventricles. The levels of B-type natriuretic peptide (BNP) are elevated in patients with left ventricular dysfunction. BNP levels correlate with both the severity of symptoms and the prognosis in congestive heart failure.

BNP levels are higher in patients with dyspnea (shortness of breath) due to heart failure than in patients with dyspnea from other causes. Rapid measurement of BNP in the emergency department therefore helps in the evaluation and treatment of patients with acute dyspnea and reduces the time to discharge and the cost of their treatment.

BNP appears to be a useful marker of cardiovascular risk, even in people with no clinical evidence of cardiovascular disease. The levels of BNP predict the risk of heart failure, first cardiovascular events, atrial fibrillation, and stroke or transient ischemic attack.

See also: Natriuretic peptide.