FT4/FT3 ratio: A novel biomarker predicts coronary microvascular dysfunction (CMD) in euthyroid INOCA patients

Abstract

BackgroundIschemia and no obstructive coronary artery disease (INOCA) patients who presented coronary microvascular dysfunction (CMD) demonstrate a poor prognosis, yet the risk factors for CMD remain unclear. Subtle changes in thyroid hormone levels within the normal range, especially the free thyroxine (FT4)/free triiodothyronine (FT3) ratio, have been shown to regulate the cardiovascular system. This prospective study investigated the correlation between FT4/FT3 ratio and CMD in euthyroid patients with INOCA.MethodsThis prospective study (www.chictr.org.cn/, ChiCTR2000037112) recruited patients with myocardial ischemia symptoms who underwent both coronary angiography (CAG) and myocardial perfusion imaging (MPI) with dynamic single-photon emission computed tomography (D-SPECT). INOCA was defined as coronary stenosis< 50% and CMD was defined as coronary flow reserve (CFR)<2.5. All patients were excluded from abnormal thyroid function and thyroid disease history.ResultsAmong 71 INOCA patients (15 [21.1%] CMD), FT4 and FT4/FT3 ratio in CMD group were significantly higher and both showed significantly moderate correlation with CFR (r=-0.25, p=0.03; r=-0.34, p=0.003, respectively). The ROC curve revealed that FT4/FT3 ratio had the highest efficacy for predicting CMD with an optimized cutoff value>3.39 (AUC 0.78, p<0.001, sensitivity, 80.0%; specificity, 71.4%). Multivariate logistic regression showed that FT4/FT3 ratio was an independent predictor of CMD (OR 7.62, 95% CI 1.12-51.89, p=0.038, P for trend=0.006).ConclusionIn euthyroid INOCA patients, increased FT4/FT3 ratio levels are associated with the occurrence of CMD, presenting a novel biomarker for improving the risk stratification.

Relationship between Thyroid Feedback Quantile‐based Index and cardiovascular diseases in a population with normal thyroid function: Evidence from the National Health and Nutrition Examination Survey 2007–2012

“…Over the years, significant attention has been given to the effect of hyperthyroidism or hypothyroidism on CVD. However, recent research has suggested that even in individuals with normal function of the thyroid, higher levels of thyroid hormone resistance index are associated with an increased incidence and adverse prognosis of CVD 12,13,16,17 . Furthermore, there is a greater incidence of diabetes, obesity, and metabolic syndrome in individuals with elevated thyroid hormone resistance index 18,19 .…”

“…However, recent research has suggested that even in individuals with normal function of the thyroid, higher levels of thyroid hormone resistance index are associated with an increased incidence and adverse prognosis of CVD. 12 , 13 , 16 , 17 Furthermore, there is a greater incidence of diabetes, obesity, and metabolic syndrome in individuals with elevated thyroid hormone resistance index. 18 , 19 Our study aligns with these prior findings, as we found a positive connection between TFQI and the incidence of CVD and a strong association with diabetes.…”

ANOCA patients with and without coronary vasomotor dysfunction present with limited electrocardiographic remodeling

“…In addition, thyroid hormone levels can influence the QTc interval. Higher levels of free thyroxine (FT4) and the ratio between FT4 and free triiodothyronine were observed in patients with ischemia and non-obstructive coronary artery disease with CMD compared to patients without CMD [9] . Baseline differences might therefore have influenced the results.…”

The prognostic value of CZT SPECT myocardial blood flow (MBF) quantification in patients with ischemia and no obstructive coronary artery disease (INOCA): a pilot study

“…Dynamic imaging was reconstructed into 32 frames (21 frames 3s, 1 frame 9s, 1 frame 15s, 1 frame 21s, 1 frame 27s, and 7 frames 30s) as previously described [ 16 ]. An ordered subset expectation maximization (OSEM) iterative algorithm was used to reconstruct the images (4 iterations and 32 subsets).…”