BACKGROUND AND OBJECTIVES: In acute coronary syndrome (ACS), the B-type natriuretic peptide (BNP) level is a strong predictor of mortality. Most ACS patients have a history of myocardial infarction (MI) or high risk ACS, clinical entities that are anticipated to lead to elevated BNP levels. Therefore, we assessed the relationship between BNP levels and long-term prognosis in low-risk patients with unstable angina (UA). SUBJECTS AND METHODS: Between September 2002 and June 2004, BNP was measured in baseline samples from 137 patients referred for angiography. UA was defined as a clinical diagnosis paired with significant coronary artery narrowing. Patients had to exhibit no ST segment changes or abnormal Q waves, no elevation of cardiac enzymes, and no abnormal left ventricular diastolic or systolic function or regional wall motional abnormality on echocardiography. Major adverse cardiac events (MACEs) were defined as cardiovascular death, MI, or readmission due to heart failure. RESULTS: The mean patient age was 62.2+/-10 years, and 70 (51.1%) of the patients were men. The mean follow-up duration was 44.5 months. Six patients died due to cardiac causes, 4 were admitted due to heart failure, and 2 had MIs. The mean BNP level was not different between patients suffering MACEs and those not suffering MACEs. Other characteristics were similar between the groups. Kaplan-Meier survival curves showed a statistically significant benefit in the BNP < or =80 pg/mL group (p=0.037). There were no significant prognostic factors on multivariate analysis. CONCLUSION: A single BNP measurement was not an independent prognostic factor, but was related to event-free survival in patients with low-risk UA.