Immature Surfactant Protein Type-B Associates With Graft Patency in Patients Undergoing Coronary Artery Bypass Grafting

BACKGROUND: Coronary artery bypass graft (CABG) surgery is performed in patients with complex multivessel coronary artery disease, but long-term graft occlusion remains a major limitation. The immature surfactant protein type-B (proSP-B) has emerged as a predictor of adverse cardiovascular outcomes. OBJECTIVES: The purpose of this study was to examine the relationship between preoperative plasma proSP-B and graft occlusion 18 months post-CABG. The aims were to evaluate whether elevated proSP-B could predict graft occlusion and to assess its predictive value within a multivariable model for long-term graft patency. METHODS: We evaluated proSP-B in relation to graft occlusion in 40 patients with occluded grafts (cases) and 130 patients without occlusions (noncases), with 18-month graft patency assessed by coronary computed tomography angiography and/or invasive angiography. Logistic regression assessed the association between proSP-B and graft occlusion. Predictive performance was evaluated using receiver-operating characteristic curves and category-free net reclassification improvement. RESULTS: Preoperative proSP-B was significantly elevated in cases compared to noncases (24.0 [IQR: 19.8-31.0] AU vs 19.4 [IQR: 14.0-25.0] AU; P = 0.002). In a multivariable analysis, proSP-B associated with increased risk of graft occlusion, even after adjusting for factors like D-dimer, left ventricular ejection fraction, and extracorporeal circulation time. Including proSP-B in a reference model improved the area under the curve from 0.7204 to 0.7733, significantly enhancing patient classification (net reclassification improvement = 0.43; SE = 0.18; P = 0.02). CONCLUSIONS: Elevated preoperative proSP-B is independently associated with 18-month graft occlusion following CABG. Including proSP-B improves existing predictive models, supporting its role as a novel biomarker for risk stratification in surgical revascularization.