Association between serum triiodothyronine level and coronary artery disease in elderly patients with low triiodothyronine syndrome

Objective To investigate the coronary artery lesion in elderly patients with coronary heart disease combined with low three triiodothyronine (T3) syndrome, analyze the correlation between T3 serum hormone levels and the coronary artery disease. Methods A total of 986 cases with low T3 syndrome in elderly patients with coronary artery disease as group A (low T3 group), 1 074 cases with normal free triiodothyronine (FT3), free thyroxine (FT4), thyroid stimulating hormone (TSH) in elderly patients of coronary heart disease as group B (control group). The levels of FT3, FT4, TSH in two groups were determined, The level of coronary artery disease was evaluated by lesion count and Gensini score according to the results of coronary arteriongraphy, analysis. Results Group A had higher age than the group B (P<0.05). The levels of total cholesterol and LDL-C were higher in group A than in group B (P<0.05). Serum FT3 values, in group A was lower than group B 〔(1.0±0.6) pmol/Lvs.(4.1±0.5) pmol/L, P<0.05)〕, serum FT4 and TSH were no significant different between the two groups. Group A's total gensini score was higher than group B〔(43.5±18.3)vs.(24.5±10.1), P<0.05)〕. As the characteristics of coronary artery lesion, 3 vessel disease incidence was higher in the low T3 group than that of control group (P< 0.05). In the low T3 group, severe coronary artery stenosis (arbitrary 1 of 3 major vascular stenosis in excess of 75%) and complete occlusion (arbitrary 1 of 3 major vascular occlusion) were higher compared with group B (P<0.05). Multivariate logistic regression analysis showed that age and low FT3 were related to number and degree of coronary artery lesions. Conclusions The lesion of coronary heart disease in the elderly patients with low T3 syndrome are mainly multivessel and two-vessel involving a wide range and higher severity. Key words: Coronary disease; Triiodothyronine; Thyroxine