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Hypothyroidism was 300% More Frequent than Hyperthyroidism in Patients with Atrial Fibrillation Enrolled Over 10 Years
LETTER
Hypothyroidism was 300% More Frequent than Hyperthyroidism in Patients with Atrial Fibrillation Enrolled Over 10 Years To the Editor: I read the review article “Thyroid and the Heart”1 with keen interest. An important point was raised by Jolobe in his letter,2 which was published in The American Journal of Medicine, stating that “For the sake of completeness, the review of “Thyroid and the Heart” should have included the coincidental association of hypothyroidism and atrial fibrillation, especially in the elderly, because both disorders are age related.” I also read the reply of the authors, who quoted a large cohort study showing that patients with both overt and subclinical hypothyroidism had a lower risk of atrial fibrillation compared with euthyroid individuals. In their reply, the authors disagree with the issue raised by Jolobe. I present some interesting evidence on this issue from another article published in The American Journal Medicine, the “History of Thyroid Disorders in Relation to Clinical Outcomes in Atrial Fibrillation.”3 Bruere et al3 studied 8962 patients with atrial fibrillation who were enrolled over 10 years and followed up. They recorded clinical events (stroke/systemic embolism, bleeding, all-cause death) on follow-up and related them to thyroid
Funding: None. Conflict of Interest: None. Authorship: The author had access to the data and played a role in writing this manuscript.
0002-9343/$ -see front matter Ó 2015 Elsevier Inc. All rights reserved.
status and disorders at the time of enrollment. They found no significant difference in the rates of these events in patients with a history of thyroid dysfunction vs those without thyroid problems in univariate or multivariable analysis. I want to highlight that of 8962 patients with atrial fibrillation who were enrolled over 10 years, only 141 had a history of hyperthyroidism, whereas 540 had a history of hypothyroidism.3 The history of hypothyroidism was thus 300% more than that of hyperthyroidism in patients with atrial fibrillation over 10 years. The authors may have overlooked an important aspect because this probably was not their focus. The evidence from this article suggests that association of hypothyroidism with atrial fibrillation cannot be overlooked. To add to the evidence, Zhang et al’s4 animal study has proven that there is increased inducibility of atrial fibrillation in hypothyroid rats. Vivek Chauhan, MD Department of Medicine Dr Rajendra Prasad Government Medical College, Tanda Himachal Pradesh, India
http://dx.doi.org/10.1016/j.amjmed.2015.06.012
References 1. Grais IM, Sowers JR. Thyroid and the heart. Am J Med. 2014;127: 691-698. 2. Jolobe OMP. Thyroid Heart Disease Should Include the Coincidental Association of Hypothyroidism and Atrial Fibrillation. Am J Med. 2015;128(3):e9. 3. Bruere H, Fauchier L, Bernard Brunet A, et al. History of thyroid disorders in relation to clinical outcomes in atrial fibrillation. Am J Med. 2015;128:30-37. 4. Zhang Y, Dedkov EI, Teplitsky D, et al. Both hypothyroidism and hyperthyroidism increase atrial fibrillation inducibility in rats. Circ Arrhythm Electrophysiol. 2013;6:952-959.
Hypothyroidism was 300% More Frequent than Hyperthyroidism in Patients with Atrial Fibrillation Enrolled Over 10 Years To the Editor: I read the review article “Thyroid and the Heart”1 with keen interest. An important point was raised by Jolobe in his letter,2 which was published in The American Journal of Medicine, stating that “For the sake of completeness, the review of “Thyroid and the Heart” should have included the coincidental association of hypothyroidism and atrial fibrillation, especially in the elderly, because both disorders are age related.” I also read the reply of the authors, who quoted a large cohort study showing that patients with both overt and subclinical hypothyroidism had a lower risk of atrial fibrillation compared with euthyroid individuals. In their reply, the authors disagree with the issue raised by Jolobe. I present some interesting evidence on this issue from another article published in The American Journal Medicine, the “History of Thyroid Disorders in Relation to Clinical Outcomes in Atrial Fibrillation.”3 Bruere et al3 studied 8962 patients with atrial fibrillation who were enrolled over 10 years and followed up. They recorded clinical events (stroke/systemic embolism, bleeding, all-cause death) on follow-up and related them to thyroid
Funding: None. Conflict of Interest: None. Authorship: The author had access to the data and played a role in writing this manuscript.
0002-9343/$ -see front matter Ó 2015 Elsevier Inc. All rights reserved.
status and disorders at the time of enrollment. They found no significant difference in the rates of these events in patients with a history of thyroid dysfunction vs those without thyroid problems in univariate or multivariable analysis. I want to highlight that of 8962 patients with atrial fibrillation who were enrolled over 10 years, only 141 had a history of hyperthyroidism, whereas 540 had a history of hypothyroidism.3 The history of hypothyroidism was thus 300% more than that of hyperthyroidism in patients with atrial fibrillation over 10 years. The authors may have overlooked an important aspect because this probably was not their focus. The evidence from this article suggests that association of hypothyroidism with atrial fibrillation cannot be overlooked. To add to the evidence, Zhang et al’s4 animal study has proven that there is increased inducibility of atrial fibrillation in hypothyroid rats. Vivek Chauhan, MD Department of Medicine Dr Rajendra Prasad Government Medical College, Tanda Himachal Pradesh, India
http://dx.doi.org/10.1016/j.amjmed.2015.06.012
References 1. Grais IM, Sowers JR. Thyroid and the heart. Am J Med. 2014;127: 691-698. 2. Jolobe OMP. Thyroid Heart Disease Should Include the Coincidental Association of Hypothyroidism and Atrial Fibrillation. Am J Med. 2015;128(3):e9. 3. Bruere H, Fauchier L, Bernard Brunet A, et al. History of thyroid disorders in relation to clinical outcomes in atrial fibrillation. Am J Med. 2015;128:30-37. 4. Zhang Y, Dedkov EI, Teplitsky D, et al. Both hypothyroidism and hyperthyroidism increase atrial fibrillation inducibility in rats. Circ Arrhythm Electrophysiol. 2013;6:952-959.