Cardiorenal stress phenotyping using the log-transformed bun-to-ejection fraction ratio improves prediction of recurrent ischemic events in young patients with acute coronary syndrome
A Celik, H Erdem, S BabacanAbstract
Background
Young patients with acute coronary syndrome (ACS) represent a distinct clinical population with a substantial residual risk of recurrent ischemic events despite contemporary therapies and guideline-directed management. Traditional risk models are primarily derived from older populations and may not adequately capture the interplay between cardiac dysfunction and systemic stress in younger individuals. Biomarkers reflecting integrated cardiorenal stress may provide additional prognostic insights and improve individualized risk stratification.
Purpose
To investigate whether cardiorenal stress phenotyping using the log-transformed blood urea nitrogen to left ventricular ejection fraction ratio (log[BUN/EF]) provides incremental prognostic value beyond conventional clinical risk factors for predicting recurrent ischemic events in a young ACS population beyond conventional clinical risk factors.
Methods
This retrospective cohort study included 672 consecutive patients presenting with ACS. A baseline clinical model incorporating age, sex, diabetes, hypertension, smoking status, clinical presentation, and multivessel diseases was developed. The incremental value of log(BUN/EF) was assessed using receiver operating characteristic (ROC) analysis, net reclassification improvement, integrated discrimination improvement, calibration metrics, and decision curve analysis to evaluate clinical utility. Median follow-up was 3.5 years (IQR 2.0–4.7 years).
Results
During follow-up, 50 patients (7.4%) experienced recurrent ischemic events. Addition of log(BUN/EF) significantly improved model discrimination, increasing the area under the curve from 0.78 to 0.84 (ΔAUC +0.056; p=0.0005). Continuous net reclassification improvement was 0.65 (95% CI 0.37–0.91; p<0.001), and the integrated discrimination improvement was 0.063 (95% CI 0.03–0.09; p<0.001). The calibration remained robust with a calibration slope near unity and a lower Brier score (0.060 vs 0.064), indicating a reduced prediction error. Decision curve analysis demonstrated higher net clinical benefit across clinically relevant threshold probabilities, supporting the clinical relevance of incorporating log(BUN/EF) into the risk assessment.
Conclusions
Cardiorenal stress phenotyping using log(BUN/EF), a simple and widely available biomarker integrating renal function and ventricular performance, provides significant incremental prognostic information beyond traditional risk factors and may enhance individualized risk stratification in young patients with ACS.tablesfigures