Elevated B-Type Natriuretic Peptide as a Predictor of Unfavorable Outcomes in Post-Acute Stroke Patients.

Background: B-type natriuretic peptide (BNP) is a key biomarker for heart failure (HF) and widely used for risk stratification. Elevated BNP levels in acute stroke are linked to poor outcomes, but its prognostic value in the post-acute phase remains unclear. Methods and Results: This retrospective study included 876 patients admitted to a rehabilitation hospital after acute cerebral infarction or hemorrhage between February 2019 and December 2022. Patients were classified into 4 groups based on BNP or N-terminal prohormone of BNP. The primary outcome was all-cause unfavorable events, including in-hospital death or transfer due to worsening condition. The severely elevated BNP group had a significantly higher risk of all-cause unfavorable events (hazard ratio: 2.34; 95% confidence interval: 1.26-4.32) than the normal group. No significant difference was observed in the mildly or moderately elevated BNP groups. BNP showed superior predictive value over HF diagnosis in terms of area under the receiver operating characteristic curve (0.712 vs. 0.691), net reclassification improvement (0.304, P=0.002), and integrated discrimination improvement (0.025, P=0.015). Higher BNP was associated with lower body mass index, reduced estimated glomerular filtration rate, longer time from stroke onset, atrial fibrillation, and cardioembolic stroke. Conclusions: BNP levels in the post-acute stroke phase were significantly associated with unfavorable outcomes and may serve as a useful prognostic marker.