INTRODUCTION NT-proBNP is the gold-standard biomarker for diagnosing and monitoring congestive heart failure (CHF); however, its role in detecting atrial fibrillation (AFib) is gaining attention. This study assessed the influence of aberrant cardiac rhythms on plasma NT-proBNP (pNT) considering urinary NT-proBNP (uNT) as a noninvasive alternative in selected clinical scenarios. METHODS In 824 patients presenting with chest pain at the emergency department of the University Hospital of Regensburg, pNT was assessed. A subset of 355 patients additionally provided uNT. RESULTS Both pNT and uNT were significantly increased in AFib, and lesser in atrial flutter (AFlut) and right ventricular (RV) pacing compared to SR (each p < 0.05). A pNT cutoff of 900 pg/mL yielded 74% sensitivity and 83% specificity for discriminating AFib from SR (AUC = 0.85). In multivariate regression, pNT or uNT and history of AFib were independent predictors of AFib (p < 0.05). CONCLUSION Both pNT and uNT are significantly elevated in AFib, and to a lesser extent AFlut, and RV pacing independently of heart failure. These findings align with prior observations and provide further evidence supporting adequately powered prospective studies to evaluate rhythm-adjusted diagnostic thresholds for CHF in AFib. In addition, uNT may complement pNT when venous access is difficult or serial remote monitoring is required.
