Association of the stress hyperglycemia ratio with coronary artery disease complexity as assessed by the SYNTAX score in patients with acute coronary syndrome

Background Mounting evidence supports a significant correlation between the stress hyperglycemia ratio (SHR) and both short- and long-term prognoses in patients with acute coronary syndrome (ACS). Nevertheless, research examining the association between the SHR and the complexity of coronary artery disease (CAD) is scarce. Therefore, this study aimed to explore the association between the SHR and CAD complexity, as assessed by the SYNTAX score, in patients with ACS. Methods A total of 4715 patients diagnosed with ACS were enrolled and divided into five groups according to the quintiles of the SHR. CAD complexity was assessed using the SYNTAX score and categorized as low (<= 22) or mid/high (> 22) levels. Logistic regression was utilized to examine the association between the SHR and CAD severity (mid-/high SYNTAX score). Restricted cubic spline (RCS) curves were generated to assess the association between the SHR and CAD severity. Subgroup analyses were conducted to stratify outcomes based on age, sex, diabetes mellitus (DM) status, and clinical presentation. Results Among the total ACS population, 503 (10.7%) patients had mid/high SYNTAX scores. Logistic regression analysis revealed that the SHR was an independent risk factor for mid/high SYNTAX scores in a U-shaped pattern. After adjusting for confounding variables, Q1 and Q5 demonstrated elevated odds ratios (ORs) relative to the reference category Q3, with ORs of 1.61 (95% CI: 1.19 similar to 2.19) and 1.68 (95% CI: 1.24 similar to 2.29), respectively. Moreover, the ORs for Q2 (1.02, 95% CI: 0.73 similar to 1.42) and Q4 (1.18, 95% CI: 0.85 similar to 1.63) resembled that of Q3. Compared with the merged Q2-4 group, the ORs were 1.52 (95% CI: 1.21 similar to 1.92) for Q1 group and 1.58 (95% CI: 1.25 similar to 2) for the Q5 group. Subgroup analysis revealed that the U-shaped association between the SHR and mid/high SYNTAX score was attenuated in DM patients (P for interaction = 0.045). Conclusions There were U-shaped associations between the SHR and CAD complexity in ACS patients, with an SHR ranging from 0.68 to 0.875 indicating a relatively lower OR for mid/high SYNTAX scores. Further studies are necessary to both evaluate the predictive value of the SHR in ACS patients and explore the underlying mechanisms of the observed U-shaped associations.