Serum tiroid stimülan hormon (TSH) düzeyinin koroner kollateral arter gelişimine etkisi
Association Between Serum Thyroid Stimulating Hormone (TSH) Levels and Coronary Collateral Development Introduction: Coronary collaterals are an alternative source of blood supply to the myocardium jeopardized by ischemia. Animal studies have shown that thyroid hormones are pro-angiogenic for the development of blood vessels. Yet, there are no clinical trials investigating the association between the serum thyroid hormones and coronary collateral circulation. In the study, we aimed to analyze the effects of the serum thyroid stimulating hormone (TSH) levels and different thyroid clinics on the development of coronary collaterals. Materials and Methods: Five hundred and sixty-one consecutive patients who have undergone coronary angiography and had at least one major coronary artery stenosis of ≥ 90% were enrolled in the study. Collateral development was graded according to the Cohen-Rentrop method. Grades were divided into two subgroups; patients with grade 0-1 collateral development were defined as having poor collateral and patients with grade 2-3 collateral development were defined as having good collateral. Then, association between the serum thyroid hormones and the coronary collateral circulation was assessed. Subsequently, participants were divided into three subgroups according to the thyroid hormone levels; euthyroidism, subclinical hyperthyroidism, and subclinical hypothyroidism. After that, the effect of different thyroid clinics on the coronary collateral formation was investigated.Results: Mean age of the patients in the study was 63.5 ± 10.7 years. 425 of the cases (75.8%) were men and 136 of them (24.2%) were women. Serum triglyceride (153.0 ± 78.6 mg/dL vs. 176.9 ± 74.3 mg/dL, p=0.03) and TSH (1.99 μIU/ml vs. 2.30 μIU/ml, p=0.02) levels were lower in patients with good collaterals compared to those with poor collaterals. Subjects with good collaterals were significantly more likely to have severe lesion location on the right coronary artery (RCA) (72.4% vs.52.2%, p<0.01). Other demographic characteristics, laboratory data and cardiovascular medications were similar among the groups. Then, the effect of different thyroid clinics on the development of coronary collaterals was investigated, and found that good collateral formation was statistically higher with a significant degree in the subclinical hypothyroidism group (21.1% vs. 8.2%, p<0.001). After that, the association between the various clinical characteristics and the extent of the collaterals was assessed by using univariate and multivariate regression models. Analysis of data has revealed that lesion location on the RCA and presence of subclinical hyperthyroidism were independent predictors of better collateral development [(OR: 1.87, 95%CI 1.15-3.03, p=0.01 for the RCA), and (OR: 2.35, 95% CI 1.05-5.29, p=0.04 for subclinical hyperthyroidism)]. Conclusion: We demonstrated that subclinical hyperthyroidism is associated with better coronary collateral formation. To the best of our knowledge, our study assessed for the first time, the effects of the serum thyroid hormones and different thyroid clinics on the development of coronary collaterals. Nonetheless, we believe that, it is necessary to analyze the influence of thyroid hormones on the coronary collateral circulation through larger, prospective, and randomized trials.