Background: In patients with symptoms of heart failure, elevations in B-type natriuretic peptide (BNP) accurately identify ventricular dysfunction. However, BNP levels are not specific for ventricular dysfunction in patients who do not have overt symptoms of heart failure, suggesting that other cardiac processes such as myocardial ischemia may also cause elevations in BNP.
Methods and results: To determine whether BNP elevations are associated with myocardial ischemia, we measured plasma BNP levels before performing exercise treadmill testing with stress echocardiography in outpatients with stable coronary disease. Of the 355 participants, 113 (32%) had inducible ischemia. Compared with participants in the lowest BNP quartile (0 to 16.4 pg/mL), those in the highest quartile of BNP (> or =105 pg/mL) had double the risk of inducible ischemia (adjusted relative risk, 2.0; 95% CI, 1.2 to 2.6; P=0.008). The relation between elevated BNP levels and inducible ischemia was especially evident in the 206 participants who had a history of myocardial infarction (adjusted relative risk, 2.6; 95% CI, 1.5 to 3.7, P=0.002) and was absent in those without a history of myocardial infarction (adjusted relative risk, 1.0; 95% CI, 0.3 to 2.2; P=0.9). This association between BNP levels and inducible ischemia remained strong after adjustment for measures of systolic and diastolic dysfunction.
Conclusions: Elevated levels of BNP are independently associated with inducible ischemia among outpatients with stable coronary disease, particularly among those with a history of myocardial infarction. The observed association between BNP levels and ischemia may explain why tests for BNP are not specific for ventricular dysfunction among patients with coronary disease.