title: Coronary flow reserve is impaired in subclinical hypothyroidism.
abstract: OBJECTIVE
  Although the cardiovascular system is highly sensitive to thyroid hormones, the cardiovascular effects of subtle thyroid dysfunction such as subclinical hypothyroidism (SHT) remain unclear. Therefore, we investigated coronary flow reserve (CFR) reflecting coronary microvascular function in patients with SHT.
  
  
  METHODS
  Fifty subjects with SHT and 30 control subjects with normal serum thyroid hormones and TSH levels were included in this study. Coronary diastolic peak flow velocities were measured at baseline and after dipyridamole infusion. CFR was calculated as the ratio of hyperemic to baseline diastolic peak velocity.
  
  
  RESULTS
  Age, gender, diastolic and systolic blood pressure, body mass index (BMI), serum lipid parameters, and thyroid hormone levels were similar between the groups. Heart rate was significantly lower in the SHT group. Left ventricular diastolic filling parameters were significantly different in the SHT group while other echocardiographic parameters were similar. CFR values were significantly lower in subjects with SHT than in the control group (2.38 +/- 0.44 vs. 2.98 +/- 0.47, p < 0.0001).
  
  
  CONCLUSIONS
  These findings suggest that CFR, which reflects coronary microvascular function, is impaired in patients with SHT.
authors.affiliation: Cardiology Department, Baskent University, Faculty of Medicine, Ankara, Turkey. semrab@baskent-kon.edu.tr
authors.forename: Semra
authors.initials: S
authors.lastname: Baycan
authors.forename: Dogan
authors.initials: D
authors.lastname: Erdogan
authors.forename: Mustafa
authors.initials: M
authors.lastname: Caliskan
authors.forename: Baris Onder
authors.initials: BO
authors.lastname: Pamuk
authors.forename: Ozgur
authors.initials: O
authors.lastname: Ciftci
authors.forename: Hakan
authors.initials: H
authors.lastname: Gullu
authors.forename: Aylin
authors.initials: A
authors.lastname: Yildirir
authors.forename: Nilgun D
authors.initials: ND
authors.lastname: Guvener
authors.forename: Haldun
authors.initials: H
authors.lastname: Muderrisoglu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D015992:Body Mass Index; D016022:Case-Control Studies; D003326:Coronary Circulation; D003971:Diastole; D004452:Echocardiography / Q000379:methods; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000150:complications* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D009206:Myocardium / Q000473:pathology; D013972:Thyrotropin / Q000378:metabolism
chemical_list: D013972:Thyrotropin