Background: Although thyroid hormones have significant effect on cardiovascular system, the impact of subtle thyroid dysfunction such as subclinical hypothyroidism (SCH) remains to be determined. We investigated coronary flow reserve (CFR) in patients with subclinical hypothyroidism.
Methods: Thirty two subjects with SCH and eighteen control subjects with normal serum thyroid hormones and thyroid-stimulating hormone (TSH) levels were included in the study. TSH, free thyroxine, free triiodothyronine, glucose, insulin, HbA1c, cholesterol, triglyceride and plasma levels of C-reactive protein were measured. Coronary diastolic peak flow velocities in left anterior descending coronary artery were measured at baseline and after adenosine infusion. CFR was calculated as the ratio of hyperemic to baseline diastolic peak velocity.
Results: CFR values were not significantly different between the two groups (SCH 2.76±0.35 vs controls 2.76±0.42). There was a significant correlation of CFR with waist to hip ratio, hypertension, smoking habits, markers of glucose status (glucose level, HbA1c, insulin level, HOMA IR), cholesterol, LDL-cholesterol and triglyceride levels in SCH group, whereas only cholesterol level showed significant correlation with CFR in controls. There was no correlation between CFR and thyroid hormones.
Conclusions: We concluded that there is a different impact of cardiovascular risk factors on CFR in SCH patients compared to healthy control and that these two groups behave differently in the same circumstances under the same risk factors. The basis for this difference could be that the altered thyroid axis "set point" changes the sensitivity of the microvasculature in patients with SCH to known risk factors.
Uvod: Poznato je da tiroidni hormoni imaju značajan efekat na kardiovaskularni sistem, ali i dalje ostaje da se utvrdi uticaj suptilnih promena na nivou tiroidne osovine kao što je subklinička hipotireoza (SHT). Ispitivali smo koronarnu rezervu protoka (KRP) kod pacijenata sa subkliničkim hipotireoidizmom.
Metode: Trideset dva ispitanika sa subkliničkom hipotireozom i osamnaest kontrolnih ispitanika sa urednim tiroidnim hormonskim statusom su bili uključeni u studiju. Mereni su TSH, fT4, fT3, glukoza, insulin, HbA1c, holesterol, trigliceridi i CRP. Koronarne dijastolne brzine protoka u levoj prednjoj silaznoj koronarnoj arteriji merene su na početku i nakon infuzije adenozina. Koronarna rezerva protoka je izračunata kao odnos hiperemijske i osnovne dijastolne brzine protoka.
Rezultati: Vrednosti koronarne rezerve protoka se nisu značajno razlikovale između dve grupe (SHT 2,76 ± 0,35 u odnosu na kontrole 2,76 ± 0,42). Postojala je značajna korelacija KRP sa odnosom struka i kukova, hipertenzijom, navikama pušenja, markerima glikoregulacije (nivo glukoze, HbA1c, nivo insulina, HOMA IR), holesterolom, LDL holesterolom i nivoom triglicerida u SHT grupi, dok je samo nivo holesterola pokazao značajnu korelaciju sa KRP u kontrolnoj grupi. Nije bilo korelacije između KRP i hormona štitaste žlezde.
Zaključak: Zaključili smo da postoji drugačiji uticaj kardiovaskularnih faktora rizika na koronarnu rezervu protoka kod pacijenata sa subkliničkom hipotireozom u poređenju sa zdravom kontrolom i da se ove dve grupe ponašaju različito u istim okolnostima, pod istim faktorima rizika. Osnova za ovu razliku mogla bi biti da promenjen "set point" tiroidne osovine menja osetljivost mikrovaskulature kod pacijenata sa SHT na poznate faktore rizika.
Keywords: cardiovascular risk factors; coronary flow reserve; subclinical hypothyroidism; thyroid.
2022 Mirjana Stojković, Biljana Nedeljković-Beleslin, Milorad Tešić, Zoran Bukumirić, Jasmina Ćirić, Miloš Stojanović, Marija Miletić, Ana Đorđević-Dikić, Vojislav Giga, Branko Beleslin, Miloš Žarković, published by CEON/CEES.