Abstract
BACKGROUND: This study was designed to investigate the impact of the serum free triiodothyronine to free thyroxine ratio (FT3/FT4) on both the incidence and long-term prognosis of contrast-induced nephropathy (CIN) following elective percutaneous coronary intervention (PCI). METHODS: This retrospective study was conducted among patients who underwent elective PCI at the Second Hospital of Tianjin Medical University from January 1, 2019, to March 31, 2022. The diagnosis of CIN was established when serum creatinine (SCr) level increased by more than 44.2 mol/L (0.5 mg/dL) or 25% compared to baseline within 48-72 h post-PCI. Logistic regression analysis was employed to identify independent predictors of CIN. Cox regression and survival analysis were utilized to assess factors influencing all-cause and cardiovascular mortality. Furthermore, the correlation between FT3/FT4 and the occurrence of CIN was examined via restricted cubic spline (RCS) analysis. RESULTS: The study encompassed a cohort of 1,390 patients, out of whom 173 (12.4%) experienced CINs. Patients diagnosed with CIN exhibited advanced age, a greater prevalence of acute myocardial infarction (AMI) and chronic renal dysfunction, along with a lower level of FT3/FT4 (all P < 0.001). Stratification based on FT3/FT4 quartile resulted in four distinct patient groups. Notably, significant distinctions emerged among the groups in terms of CIN occurrence, all-cause mortality, cardiovascular mortality. RCS analysis depicted a J-shaped relationship between FT3/FT4 levels and the incidence of CIN. The curve showed an inflection point at an FT3/FT4 ratio of approximately 0.306. CIN risk initially decreases and then increases with the increase of FT3/FT4 ratio. Several factors were identified as risk factors for all-cause mortality, including age, myocardial infarction, LVEDD, SCr before PCI, diuretic usage, left main coronary artery disease, and left circumflex artery disease. Conversely, diastolic blood pressure, serum albumin, post ballooning, statin usage, and FT3/FT4 demonstrated protective effects. CONCLUSION: The FT3/FT4 level was significantly associated with both incidence of CIN and long-term all-cause mortality in patients undergoing elective PCI.