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Keywords:

  • atrial fibrillation;
  • biomarker;
  • cryptogenic;
  • diagnosis;
  • NT-proBNP;
  • stroke

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.