Abstract Background/Introduction Coronary angiographic complexity, reflected by the Syntax score, is a well-established determinant of outcomes after coronary artery bypass surgery (1). However, malnutrition and immune-inflammatory imbalance, represented by the Prognostic Nutritional Index (PNI), have been increasingly recognized as important prognostic factors in cardiovascular surgery (2). Low PNI reflects decreased serum albumin and lymphocyte levels, both associated with impaired recovery and increased mortality after major operations (2). Whether the prognostic value of PNI remains significant regardless of coronary anatomical complexity remains unclear. Purpose This study aimed to investigate the relationship between the Prognostic Nutritional Index and early mortality after coronary artery bypass surgery and to assess its interaction with the Syntax score. We hypothesized that a low PNI would predict higher early mortality even in patients with less complex coronary anatomy. Methods A total of 219 patients undergoing isolated coronary artery bypass surgery were retrospectively analyzed. The Prognostic Nutritional Index was calculated as (10 × serum albumin g/dL) + (0.005 × lymphocyte count /mm³) (2). Patients were divided according to mortality status and Syntax score tertiles. Statistical analyses included Spearman correlation, receiver operating characteristic curve, and multivariable logistic regression adjusted for age, ejection fraction, diabetes, urea, creatinine, and Syntax score. Results There was no significant correlation between the Prognostic Nutritional Index and Syntax score (ρ = 0.045, p = 0.51). Patients who died early had lower PNI values than survivors (372 ± 52 vs. 396 ± 41, p = 0.042). In multivariable analysis, the Prognostic Nutritional Index independently predicted mortality (odds ratio = 0.989, 95% confidence interval = 0.979–0.999, p = 0.044), while the Syntax score did not. The adverse prognostic effect of low PNI persisted even among patients with low Syntax scores. The distribution of PNI by mortality and Syntax tertiles is illustrated in Figure 1. Conclusion(s) Preoperative nutritional and immune impairment, expressed by a low Prognostic Nutritional Index, increases early mortality risk after coronary artery bypass surgery, even in patients with less complex coronary anatomy. Integrating nutritional assessment into preoperative evaluation may enhance risk prediction and improve surgical outcomes.Figure 1For image description, please refer to the figure legend and surrounding text.
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