High plasma brain natriuretic peptide level in thromboembolism patients associated with nonvalvular atrial fibrillation: cause or effect?

Determinants of plasma levels of brain natriuretic peptide after acute ischemic stroke or TIA

Plasma levels of brain natriuretic peptide (BNP) are frequently elevated after an acute stroke and have been shown to be an independent predictor of mortality. However, the relationships between stroke and BNP concentrations have not yet been systematically investigated. Plasma BNP assay and echocardiography were performed in 48 patients with ischemic stroke or TIA with a mean delay of 12.7 h after onset. Median BNP concentration was 88.6 pg/mL (range 5-1270). Older age, chronic heart failure, atrial fibrillation, stroke severity, lower hemoglobin levels, lower left ventricular ejection fraction, and abnormalities of left atrium or appendage (LA/LAA) were univariately associated with increased BNP levels. At multivariable analysis, the presence of at least one LA/LAA abnormality (atrial dilatation, low flow velocity, spontaneous echocontrast or thrombus) had the strongest association with BNP, explaining 38.9% of the variance in the whole sample and 28.5% in patients without atrial fibrillation. In acute ischemic stroke patients, elevated plasma BNP levels have multiple determinants, among which left atrial disease appears to be the stronger, even in patients without atrial fibrillation. These results encourage further investigation of plasma BNP concentration as a potential marker of the presence of left atrial sources of emboli.

B-type natriuretic peptide levels in patients with paroxysmal lone atrial fibrillation

To investigate the levels of B-type natriuretic peptide (BNP) in patients with atrial fibrillation (AF) but without structural heart disease, we measured plasma BNP concentration in 61 consecutive AF patients and in 61 age- and sex-matched healthy subjects. Plasma BNP concentration in the AF group was significantly higher than in the control group (121+/-32 vs 41+/-12 pg/ml, P<0.001). Logistic regression analysis showed that age (r=0.66, P<0.001), left atrial diameter (r=0.59, P<0.01), and a history of AF (r=0.72, P<0.001) were independent predictors of elevated BNP. We concluded that BNP was elevated in patients with paroxysmal lone AF. The clinical significance of BNP elevation in these patients requires further investigation.