The Potential Role of Baseline FT3/FT4 Ratio as a Prognostic Biomarker for Patients With Ischemic Non-Obstructive Coronary Artery Disease.

BACKGROUND: Ischemia with non-obstructive coronary artery disease (INOCA) is associated with an increased risk of major adverse cardiovascular events (MACE). The relationship between thyroid function and the progression of INOCA remains unclear. This study aims to evaluate the prognostic value of the ratio of serum free triiodothyronine (FT3) to free thyroxine (FT4) in patients with INOCA.

METHODS: This study retrospectively included 109 patients who underwent coronary angiography (CAG) and synchronous single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI) in our hospital due to myocardial ischemia symptoms, and were ultimately diagnosed with INOCA. The enrolled patients were divided into high FT3/FT4 value group and low FT3/FT4 value group based on the median FT3/FT4 ratio (0.317). Regularly follow-up on MACE in patients, including cardiac death, non-fatal myocardial infarction, non-fatal stroke, heart failure, coronary revascularization, and readmission due to angina pectoris.

RESULTS: The incidence of MACE in patients with low FT3/FT4 ratio (< 0.317) was significantly higher than that in patients with high FT3/FT4 ratio (≥ 0.317), and the difference was statistically significant (p < 0.05). The proportion of readmission due to unstable angina was significantly increased in the low FT3/FT4 group (p < 0.05). Multivariate Cox regression analysis showed that patients with high FT3/FT4 ratios had a lower risk of MACE compared to those with low FT3/FT4 ratios (HR: 0.267, 95% CI: 0.076-0.937, p = 0.039).

CONCLUSIONS: Low FT3/FT4 ratio was significantly associated with increased MACE incidence in INOCA patients. FT3/FT4 ratio may be a potential biomarker to predict the prognosis of INOCA patients.