title: The prevalence and prognostic effects of subclinical thyroid dysfunction in dilated cardiomyopathy patients: a single-center cohort study.
abstract: BACKGROUND
  Subclinical thyroid dysfunction may be a risk factor for mortality in patients with heart failure and may be associated with dilated cardiomyopathy (DCM). This was a cohort study to examine the possible association between subclinical thyroid dysfunction and all-cause mortality in DCM patients, because the current evidence on this association remains elusive.
  
  
  RESULTS
  A total of 963 DCM patients were evaluated for thyroid function. Of these patients, 7.1% (n = 68) had subclinical hyperthyroidism (defined as serum thyroid-stimulating hormone [TSH] <0.35 μIU/mL), 84.7% (n = 816) had euthyroidism (TSH 0.35-5.5 μIU/mL), and 8.2% (n = 79) had subclinical hypothyroidism (TSH >5.5 μIU/mL). There was a significant difference in all-cause mortality rates between patients with euthyroidism and patients with subclinical hyper- and hypothyroidism (21%, 38.2%, and 26.6%, respectively; log-rank χ(2) = 13.104; P = .001) with mean follow-up of 3.5 years. After adjustment for other confounding factors at baseline, QRS duration, N-terminal pro-B-type natriuretic peptide, New York Heart Association functional class, left atrial diameter, and subclinical hyperthyroidism (hazard ratio 1.793, 95% CI 1.010-3.183; P = .046) emerged as significant predictors of all-cause mortality.
  
  
  CONCLUSIONS
  DCM patients with subclinical hyper- and hypothyroidism had higher all-cause mortality rates. However, only subclinical hyperthyroidism, not subclinical hypothyroidism, was an independent predictor for increased risk of all-cause mortality.
authors.affiliation: Cardiac Arrhythmia Center, Cardiovascular Institute and Fuwai Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, People's Republic of China; Department of Cardiology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, People's Republic of China.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Li
authors.affiliation: Cardiac Arrhythmia Center, Cardiovascular Institute and Fuwai Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, People's Republic of China.
authors.forename: Xinwei
authors.initials: X
authors.lastname: Yang
authors.affiliation: Biological Information and Statistics Center, Cardiovascular Institute and Fuwai Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, People's Republic of China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Cardiac Arrhythmia Center, Cardiovascular Institute and Fuwai Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, People's Republic of China.
authors.forename: Ligang
authors.initials: L
authors.lastname: Ding
authors.affiliation: Cardiac Arrhythmia Center, Cardiovascular Institute and Fuwai Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Cardiac Arrhythmia Center, Cardiovascular Institute and Fuwai Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, People's Republic of China. Electronic address: drhua@yahoo.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Hua
mesh_terms: D000328:Adult; D000368:Aged; D002311:Cardiomyopathy, Dilated / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D013959:Thyroid Diseases / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D013961:Thyroid Gland / Q000503:physiopathology
keywords: Subclinical thyroid dysfunction; dilated cardiomyopathy; survival