Coronary morphological and functional features in subclinical hypothyroidism with ST-Elevation myocardial infarction.

Background: Subclinical hypothyroidism (SH), characterized by normal free tetraiodothyronine (FT4) but high hyroid-stimulating hormone (TSH), gains attention for relationship with cardiovascular diseases. This study aims to investigate coronary artery features of non-culprit lesions in SH patients with ST-elevation myocardial infarction (STEMI) to understand their intracoronary morphological and functional characteristics.

Methods: A retrospective study of 1,570 STEMI patients with ≥ 50% non-culprit lesions analyzed coronary angiography, optical coherence tomography (OCT) imaging, & quantitative flow ratio (QFR) data. Patients were grouped based on SH status.

Results: Among them, a total of 214 patients had SH. In baseline characteristics, the SH group showed lower male and smoker rates, lower free triiodothyronine (FT3), and higher high-sensitivity C-reactive protein (hs-CRP), N terminal pro B-type natriuretic peptide (NT-proBNP), and TSH levels than the non-SH group. SH group had longer lesions, more micro-vessels, more cholesterol crystals, and lower QFR values for non-culprit lesions. Additionally, SH was an independent predictor for coronary parameters including micro-vessel, cholesterol crystal, and QFR values ≤ 0.8. And the effect of SH on those coronary parameters did not show any interaction in different subgroups.

Conclusions: There was an association between SH and specific coronary artery characteristics, including increased plaque inflammation and plaque instability (the increase of micro-vessels and cholesterol crystal detected by OCT) and potential endothelial dysfunction (the decrease of QFR value detected by QFR). Our forthcoming research will prioritize extensive, multi-center prospective studies aimed at elucidating the precise mechanisms and long-term prognosis of SH on coronary artery lesions.