B-type natriuretic peptide (BNP) levels in female systemic lupus erythematosus patients: what is the clinical significance?

Cardiovascular disease is a major cause of death in patients with systemic lupus erythematosus (SLE) especially during the late phase of the disease. This study was conducted to evaluate B-type natriuretic peptide (BNP) levels in female SLE patients without cardiac symptoms and to investigate whether BNP levels correlated with echocardiographic findings. We studied 59 women with SLE and 33 healthy women. SLE patients with history of cardiac disease, diabetes mellitus, hypertension, and other inflammatory diseases were excluded from the study. All subjects had a complete history and physical examination. Overall disease activity assessment in SLE patients at the time of the study were derived by calculation of SLE disease activity index (SLEDAI). BNP levels were determined, and transthoracic echocardiography were performed in all subjects. There was no difference between SLE patients and controls in terms of age, blood pressure, smoking status, plasma glucose, creatinine levels, and lipid profiles. Nine patients had SLEDAI score greater than 5. All subjects had an EF greater than 55%. Diastolic dysfunction was more frequent in lupus patients than in controls (15 [25.4%] vs. 2 [6%]; p = 0.022). BNP levels of SLE patients were significantly higher than controls (median 17.9 range [5–211] pg/ml vs. median 14.7 range [5–39.7] pg/ml; p = 0.033). Twenty-seven of the SLE patients (46%) and seven of the controls (21%) had BNP levels greater than or equal to 20 pg/ml (p = 0.019). There were no differences in BNP levels of SLE patients with and without diastolic dysfunction (median 17.8 range [5–117] pg/ml vs. median 18.5 range [5–211] pg/mL; p = NS). BNP levels were positively correlated with left atrium diameter (r ² = 0.39, p = 0.001). BNP levels did not correlate with erythrocyte sedimentation rate/C-reactive protein levels, SLEDAI scores, total steroid dosage used, or other echocardigraphic parameters. BNP levels were increased in female SLE patients without cardiac symptoms as compared to healthy controls. Although none of the SLE patients in our study had clinical signs of ischemic heart disease, increased levels of BNP in SLE patients might be a reflection of a ischemic myocardial tissue.