• Wajdy J. Majid Lecturer, Dept. of Biochemistry, college of medicine, Thi-Qar University


Background  Atrial fibrillation is a well known manifestation of hyperthyroidism , we studied whether subclinical hyperthyroidism in clinically euothyroid persons is a risk factor for  atrial fibrillation .  Method we studied 267  persons  , the subject was classified into 3  groups according to the serum TSH  group I:   ( 174 ) persons compromised those with normal values of serum TSH  ( 0.25 – 5 μU/ml) and T3 , T4  within normal limit , this group  considered as control group. group II:  ( 61 ) persons those  with low serum  TSH ( < 0.25 μU/ml)   and with elevated serum T3 and T4  i.e  overt hyperthyroidism. group III:   ( 32 ) persons those  with low serum TSH  ( < 0.25 μU/ml )   and T3 and T4 within normal limit  i. e. sub clinical hyperthyroidism . Result:  Atrial fibrillation ( AF )  was presented in 4 only from 174 with a percent of ( 2.3 %) in group I  ,but  9 only from 61 persons with a percent of ( 13.8 %) were presented in group II ,  while 4  only from 32 persons with a percent of  ( 12.7 %) in group III . There is significant difference ( P < 0.01 ) between group I when it compared with other groups . Conclusion:  Low serum thyrotropin concentration is associated with more than 5 fold higher likely hood for the presence of AF with no significance difference between subclinical and overt hyperthyroidism .    


Banach M, Misztal M, Goch A, Rysz J, Goch JH. Predictors of atrial fibrillation in patients following isolated surgical revascularization. A metaanalysis of 9 studies with 28 786 patients. Arch Med Sci. 2007;3:229–239.

Mariscalco G, Klersy C, Zanobini M, Banach M, Ferrarese S, Borsani P, Cantore C, Biglioli P, Sala A. Atrial Fibrillation After Isolated Coronary Surgery Affects Late Survival. Circulation. 2008;118:1612–18.

Staffurt JS, Gibberd JS, Tang FS. Arterial embolism in thyrotoxicosis with atrial fibrillation. Br Med J. 1977;2:688–690.

Agata BDimitri P M, Jacek R, and Maciej B The mechanisms of atrial fibrillation in hyperthyroidism Thyroid Res. 2009; 2: 4.

Jayaprasad N, Johnson F Atrial Fibrillation and Hyperthyroidism Indian Pacing Electrophysiol J. 2005 Oct–Dec; 5(4): 305–311.

Staffurth JS, Gibberd JS, Tang FS, et al. Arterial embolism in thyrotoxicosis with atrial fibrillation. Br Med J. 1977;2:688–690.

Lazar MA. Thyroid hormone receptors: multiple forms, multiple possibilities. Endocr Rev. 1993;24:184–193.

Shimoni Y, Severson DL. Thyroid status and potassium currents in rat ventricular myocytes. Am J Physiol. 1995;268:H576–H583.

Klein I, Ojamaa K. Thyroid hormone and the cardiovascular system. N Engl J Med. 2001;344:501–509.

Ojamaa K, Klemperer JD, Klein I. Acute effects of thyroid hormone on vascular smooth muscle. Thyroid. 1996;6:505–512.

Beirsack H.J. Hotze A. The clinician and the thyroid. Eur. J. Nucl. Med. 1991, 18,761-778.

Jyothis T G, Jonathan C T, Bruce M, Maurice P , and Vijay J,Atrial fibrillation associated with a thyroid stimulating hormone-secreting adenoma of the pituitary gland leading to a presentation of acute cardiac decompensation: A case report, Med Case Reports. 2008; 2: 67.

Welborn TA, Cumpston GN, Cullen KJ, Curnow DH, McCall MG, Stenhouse NS. The prevalence of coronary heart disease and associated factors in an Australian rural community. Am J Epidemiol. 1969;89:521-536.

Sawin CT, Geller A, Wolf P, et al. Low serum thyrotropin concentrations as a risk factor for atrial fibrillation in older persons. N Engl J Med. 1994;331:1249–1252.

Irwin K, Kaie OThyroid Hormone and the Cardiovascular System NEJM , 2001,Volume 344:501-509

Forfar J, Miller HC, Toft AD. Occult thyrotoxicosis: a reversible cause of "idiopathic" atrial fibrillation. Am J Cardiol. 1979;44:9–12.

Fazio S, Palmieri EA, Lombardi G, Biondi B. Effects of Thyroid Hormone on the Cardiovascular System. Recent Progr Horm Res. 2004;59:31–50.

Dillmann WH. Biochemical basis of thyroid hormone action in the heart. Am J Med. 1990;88:626–630.

Krahn AD, Klein GJ, Kerr CR, et al. How useful is thyroid function testing in patients with recent-onset atrial fibrillation? Arch Intern Med 1996;156:2221-2224.

Klein I, Ojamaa K. Thyrotoxicosis and the heart. Endocrinol Metab Clin North Am 1998;27:51-62.

Gilligan DM, Ellenbogen KA, Epstein AE. The management of atrial fibrillation. Am J Med 1996;101:413-421.