Little is known about the association between the free triiodothyronine/free thyroxine (FT3/FT4) ratio and clinical outcomes in euthyroid patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS) undergoing percutaneous coronary intervention (PCI). A total of 1448 euthyroid patients with NSTE-ACS who underwent PCI were included in this prospective study. Multivariate Cox regression analysis revealed that there was a significantly increased risk of stroke (hazard ratio [HR] 11.380, 95% confidence interval [CI]: 1.386-93.410, P = .024) and major adverse cardiovascular and cerebrovascular events (MACCEs) (HR 3.364, 95% CI: 1.595-7.098, P = .001) in patients in lower FT3/FT4 tertiles. The combined model of FT3/FT4 ratio and the Global Registry of Acute Coronary Events (GRACE) score provided the added value of risk assessment by improving C-statistics, integrated discrimination improvement (IDI), and the net reclassification index (NRI) (all P < .05). Thus, in euthyroid patients with NSTE-ACS undergoing PCI, the FT3/FT4 ratio was not only an independent prognostic indicator of long-term MACCE but also enhanced risk discrimination when combined with the GRACE risk score, which suggests that the calculation of FT3/FT4 before and after PCI may contribute to risk stratification in this particular patient group.
Keywords: Global Registry of Acute Coronary Events risk score; free triiodothyronine/free thyroxine ratio; major adverse cardiovascular and cerebral events; non-ST-segment elevation acute coronary syndrome.