N-terminal pro-brain natriuretic peptide shows diagnostic accuracy for detecting atrial fibrillation in cryptogenic stroke patients

Background: Diagnosing paroxysmal atrial fibrillation in patients with stroke can be difficult. We aimed to determine if N-terminal pro-brain natriuretic peptide can help identify paroxysmal atrial fibrillation in cryptogenic stroke.

Methods and results: Among 264 ischemic stroke patients, serum levels of N-terminal pro-brain natriuretic peptide were measured within 72 h of stroke onset. In cryptogenic stroke patients, 24-h Holter monitoring was used to look for paroxysmal atrial fibrillation within the first week and also three- and six-months after admission. First, patients with a defined etiology were used to construct a receiver operating characteristic curve for the diagnosis of atrial fibrillation. From this curve, the sensitivity and specificity of preestablished cutoff points for the diagnosis of atrial fibrillation were calculated. A logistic regression was performed to assess the independent relationship of the logarithm of N-terminal pro-brain natriuretic peptide levels with atrial fibrillation. The cutoff points were then evaluated in patients with cryptogenic stroke.

Results: One hundred eighty-four patients had a specific stroke etiology. Fifty-five patients had atrial fibrillation. Using multivariate analysis, the logarithm of N-terminal pro-brain natriuretic peptide levels was independently associated with atrial fibrillation. The area under the receiver operating characteristic curve of N-terminal pro-brain natriuretic peptide for the diagnosis of atrial fibrillation was 0.91 (95% confidence interval 0.87-0.95). The cutoff point of 265.5 pg/ml had a sensitivity of 100% and specificity of 70.5% for the diagnosis of atrial fibrillation. The cutoff point of 912 pg/ml had a sensitivity of 81.8% and a specificity of 87.5%. Eighty patients had a cryptogenic stroke. In 17, paroxysmal atrial fibrillation was found during follow-up. In these patients, the area under the curve for the diagnosis of paroxysmal atrial fibrillation was 0.83. The cutoff point of 265.5 had a sensitivity of 88.2% and a specificity of 61.9%. The cutoff point of 912 pg/ml had a sensitivity of 47.1% and a specificity of 88.9%.

Conclusion: N-terminal pro-brain natriuretic peptide has good accuracy in predicting the presence of paroxysmal atrial fibrillation in patients with cryptogenic stroke and can help to identify these patients.