Subclinical hypothyroidism might increase the risk of transient atrial fibrillation after coronary artery bypass grafting.
BACKGROUND
Some studies have proposed that subclinical hypothyroidism (SCH) has adverse effects on the cardiovascular system, but little is known about the effect on patients undergoing cardiovascular operations. We examined the influence of preoperative SCH on postoperative outcome in patients undergoing coronary artery bypass grafting (CABG).


METHODS
Among patients who underwent CABG between July 2005 and June 2007 at Seoul National University Bundang Hospital, 224 with normal thyroid function and 36 with SCH were enrolled. Preoperative risks and postoperative outcomes were evaluated prospectively without thyroid hormone replacement.


RESULTS
There were no significant differences in primary outcomes (major adverse cardiovascular events) and secondary outcomes such as wound problems, mediastinitis, leg infection, respiratory complications, delirium, or reoperation during the same hospitalization. However, patients with SCH had a higher incidence of postoperative atrial fibrillation than those with normal thyroid function after adjustment for age, gender, body mass index, and other independent variables such as emergency operation, the use of cardiopulmonary bypass, combined valvular operation, preoperative creatinine levels, left ventricular systolic dysfunction, and nonuse of beta-blockers (45.5% vs 29%; odds ratio, 2.552; 95% confidence interval, 1.117 to 5.830; p = 0.026).


CONCLUSIONS
SCH appears to influence the postoperative outcome for patients by increasing the development of postoperative atrial fibrillation. However, it is still unproven whether preoperative thyroxine replacement therapy for patients with SCH might prevent postoperative atrial fibrillation after CABG.
Park
Young Joo
YJ
Department of Internal Medicine, Seoul National University College of Medicine and Seoul National University Bundang Hospital, Seongnam, Korea.
Yoon
Ji Won
JW
Kim
Kwang Il
KI
Lee
You Jin
YJ
Kim
Kyung Won
KW
Choi
Sung Hee
SH
Lim
Soo
S
Choi
Dong Ju
DJ
Park
Kay-Hyun
KH
Choh
Joong Haeng
JH
Jang
Hak Chul
HC
Kim
Seong Yeon
SY
Cho
Bo Youn
BY
Lim
Cheong
C
D000368:Aged; D001281:Atrial Fibrillation / Q000453:epidemiology* / Q000209:etiology*; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000150:complications* / Q000175:diagnosis; D008297:Male; D011300:Preoperative Care; D012307:Risk Factors