Abstract 1644: B-type Natriuretic Peptide, Subclinical Atherosclerosis, and Inducible Myocardial Ischemia
Background: B-type natriuretic peptide (BNP) is associated with both coronary artery calcium (CAC), a marker of subclinical atherosclerosis, as well as myocardial ischemia and cardiac events. We examined if the utility of BNP is limited to those with pre-existing subclinical atherosclerosis.
Methods: We examined in 356 patients (mean age 60 years, 52% male) who underwent CAC screening by computed tomography and myocardial perfusion scanning (MPS) for detection of inducible ischemia whether CAC screening might identify patients where BNP predicts myocardial ischemia, defined as a sum difference score of ≥4. BNP was measured by Biosite, Inc. (San Diego, CA), with elevated levels defined both as ≥40 pg/ml and ≥100 pg/ml.
Results: Overall, persons with elevated BNP levels were more likely to demonstrate myocardial ischemia: 19% vs. 7% for BNP >=40 vs. <40 pg/ml (p<0.01) and 32% vs. 8% for BNP ≥100 vs. <100 pg/ml (p<0.001). Also, by CAC category (0, 1–99, and ≥100), elevated BNP was more frequent (BNP ≥40 pg/ml: 13.6%, 18.9%, and 28.6%, respectively; and BNP≥100 pg/ml: 3.3%, 4.4%, and 14.3%, respectively, both p≤0.01). Myocardial ischemia was significantly more likely in those with elevated BNP levels, but only among those with CAC≥100 (see table⇓ below). This relationship persisted in multivariable logistic regression only for those with CAC ≥100 upon adjustment for age, gender, other cardiac risk factors, ejection fraction, and symptoms: odds ratio (OR) (95% confidence intervals) = 4.8 (1.4–16.4) (p=0.01) for BNP ≥40 vs. <40 pg/ml and 4.5 (1.1–18.3) (p<0.05) for BNP ≥100 vs. <100 pg/ml. Prevalence of Myocardial Ischemia by BNP and CAC
Conclusions: Elevated BNP identifies a substantially increased likelihood of myocardial ischemia only when CAC≥100, suggesting its utility for predicting ischemia may be limited to those with subclinical atherosclerosis.