Association between Thyroid Function and Postoperative Outcomes in Patients with Acute Coronary Syndrome after Treatment with PCI: A Retrospective Study

Objective: This study aims to investigate the relationship between thyroid function and prognosis in acute coronary syndrome (ACS) patients after percutaneous coronary intervention (PCI). Methods: According to the thyroid function status of the patients at admission, they were divided into the euthyroid group (Group A), subclinical hyperthyroidism group (Group B), subclinical hypothyroidism group (Group C), and low T3 group (Group D). The clinical data of the four patient groups were compared. The logistic regression model was used to analyze the relationship between thyroid function and postoperative outcomes in patients with ACS undergoing PCI. Results: A total of 200 ACS patients who underwent PCI treatment in our hospital from January 2022 to October 2023 were selected as the research population. The incidences of subclinical hyperthyroidism, subclinical hypothyroidism, and low T3 syndrome were 17.00% (34/200), (36/200), and 29.50% (59/200), respectively. Univariate analysis of variance showed significant differences in age, diabetes, smoking history, systolic pressure and heart rate at admission, shock index, blood urea nitrogen (BUN), Cr, glucose (GLU), fibrinogen (FIB), glycosylated hemoglobin (HbA1c), creatine kinase isoenzyme (CK-MB), and CRP among all groups (p < 0.05). Thyroid function markers differed significantly across the groups (p < 0.001). Specifically, Group B exhibited the lowest thyroid stimulating hormone (TSH) levels (0.23 ± 0.09 mIU/L), whereas Group C displayed the highest (8.05 ± 3.72 mIU/L). Group D showed the lowest free triiodothyronine (FT3) levels (2.74 ± 0.51 pmol/L), and Group B had the highest free thyroxine (FT4) levels (16.31 ± 2.62 pmol/L). A significant difference in the incidences of cardiovascular death and heart failure was observed among the four groups (p < 0.05). Notably, Group D showed higher incidences of cardiovascular death (11.86%) and heart failure (50.85%). Similarly, at 1-year follow-up, a significant difference in the incidences of cardiovascular death and heart failure were found among the four groups (p < 0.05). Specially, Group D exhibited higher rates of cardiovascular death (15.25%) and heart failure (27.12%). Logistic regression analyses highlighted FT3 as a significant predictor of adverse events during hospitalization (OR = 0.335, 95% CI: 0.222–0.506, p < 0.001), while TSH emerged as an independent risk factor for adverse events during 1-year follow-up (OR = 1.136, 95% CI: 1.040–1.240, p = 0.005). Conclusion: Patients with ACS have a higher incidence of mild thyroid dysfunction. Compared with patients with euthyroid function, patients with low triiodothyronine (T3) syndrome have a worse prognosis after PCI treatment. Serum FT3 concentration and TSH can be used as predictors of poor prognosis in ACS patients.