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Original Articles: Adult Cardiac

Subclinical Hypothyroidism Might Increase the Risk of Transient Atrial Fibrillation After Coronary Artery Bypass Grafting

^a Department of Internal Medicine, Seoul National University College of Medicine and Seoul National University Bundang Hospital, Seongnam, Seoul, Korea
^d Department of Thoracic and Cardiovascular Surgery, Seoul National University College of Medicine and Seoul National University Bundang Hospital, Seongnam, Seoul, Korea
^b Thyroid Cancer Clinic, National Cancer Center, Gyeonggi-do, Seoul, Korea
^c Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, Korea

Accepted for publication March 12, 2009.

^_* Address correspondence to Dr Cheong Lim, Cardiovascular Center, Department of Thoracic and Cardiovascular Surgery, Seoul National University College of Medicine and Seoul National University Bundang Hospital, 300 Gumi-dong Bundang-gu, Seongnam-shi, Gyeonggi-do, 463-707, South Korea (Email: mluemoon{at}snubh.org).

	Abstract

Top Abstract Introduction Patients and Methods Results Comment Footnotes References

 
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 β-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.

	Introduction

Top Abstract Introduction Patients and Methods Results Comment Footnotes References

 
Subclinical hypothyroidism (SCH) is characterized by laboratory findings of an elevated serum thyroid stimulating hormone (TSH) level with a normal free thyroxine (T4) concentration. Overt hypothyroidism reduces cardiac contractility and leads to increased peripheral resistance, decreased cardiac preload, and increased capillary permeability [1]. The clinical significance of SCH is debated, but some have proposed that SCH might have adverse effects on the cardiovascular system [2, 3]. Furthermore, there is a report that subtle thyroid dysfunction also influenced the prognosis of patients after cardiac surgery [4].

Thyroid hormone replacement therapy improves cardiac diastolic function, and possibly systolic function and systemic vascular resistance [5]; however, the increased contractility may induce myocardial ischemia and cardiac arrhythmia, leading to congestive heart failure or myocardial ischemia in patients with coronary artery disease. For these reasons, experts have not reached a consensus about the need to replace thyroid hormone in patients with coronary artery disease undergoing cardiovascular operations. Therefore, preoperative thyroid hormone replacement in patients with SCH is not routinely recommended. We investigated whether SCH might influence the postoperative outcome after coronary artery bypass grafting (CABG) and obtained a finding that might favor preoperative thyroid hormone replacement in such patients.

	Patients and Methods

Top Abstract Introduction Patients and Methods Results Comment Footnotes References

 
Patients
Between July 2005 and June 2007 at Seoul National University Bundang Hospital, we recruited 281 patients who underwent CABG, which is the largest and homogenous cardiovascular surgical patient group in our hospital. Thyroid function tests were performed preoperatively, and patients were followed up prospectively. Of these subjects, 224 had normal thyroid function, 36 had SCH, 3 had overt hypothyroidism, 15 had subclinical hyperthyroidism, and 3 had overt hyperthyroidism. Patients with SCH or euthyroidism were selected for final analysis. Patients with SCH did not receive preoperative T4 replacement. All participants signed an informed consent before enrolling in the study and received appropriate management according to their disease status. This study was approved by the Institutional Review Board of the Seoul National University Bundang Hospital.

Medical Histories and Anthropometric Measurements
We reviewed the patients' medical and social histories. The definition of a smoker included former smokers as well as current smokers. Patients were defined to have diabetes mellitus, hypertension, or hypercholesterolemia according to their medical reports or as determined by specific treatments. Any history of a cerebrovascular accident (CVA) was determined on each patient's report, but 1 patient who had typical magnetic resonance image findings suggesting a previous asymptomatic cerebral infarction was also defined to have had CVA.

Also reviewed were chronic kidney disease, including chronic kidney disease stage 3, as defined by the National Kidney Foundation; acute renal failure, defined as a serum creatinine level of 2.0 mg/dL or higher and a 50% or greater increase from the preoperative baseline value; chronic obstructive pulmonary disease, defined as a preoperative forced expiratory volume in 1 second of less than 75%; and peripheral artery disease, defined as documented atherosclerosis of the upper and lower extremity on preoperative computed tomography (CT) angiography. Atrial fibrillation (AF) was defined on each patient's report and preoperative 12-lead electrocardiographic findings, defined as in the American College of Cardiology, American Heart Association, and European Society of Cardiology Practice Guidelines of 2006, including persistent and paroxysmal AF.

Previous medication history, especially any use of β-blockers, was also investigated. The patients' weight while wearing light clothing at admission was measured to the nearest 0.1 kg, and height was measured to the nearest 0.1 cm using an automatic height/weight scale. The body mass index (kg/m²) was calculated.

Laboratory Measurements
A venous blood sample was taken at an outpatient department within a month before operation from patients undergoing elective procedures or on admission for patients undergoing an urgent or emergency operation. Median duration between blood sampling and the operation was 3 days (range, 0 to 37 days), and 83.4% of the tests were performed within 1 week before the operation. Additional blood sampling was done immediately postoperatively and on days 1 and 2 to measure cardiac enzyme levels. Blood samples other than these were taken as needed to monitor and treat patients during their hospitalization.

For thyroid function tests, serum TSH and free T4 concentrations were measured by immunoradiometry using commercial kits (TSH, CIS Biointernational, Gif-sur-Yvette, France; FT4, DiaSorin S.p.A, Saluggia, Italy). Euthyroidism was defined as a normal level of TSH (range, 0.4 to 4.1 mIU/L) and free T4 (range, 0.7 to 1.8 ng/dL) in the absence of thyroid medication. SCH was defined as a TSH concentration greater than 4.1 mIU/L and a free T4 concentration within the normal range. Subclinical hyperthyroidism was defined as a TSH level of less than 0.4 mIU/L with a T4 concentration within the normal range.

The cardiac enzymes, creatine kinase (Toshiba 200FR, Toshiba, Japan; Dimension RxL Max, Dade Behring, Germany), creatine kinase-MB, and troponin I (Dimension RxL Max, Dade Behring), were measured. Plasma glucose concentration was measured by the glucose oxidase method using an YSI 2300 STAT glucose analyzer (Yellow Springs Instrument Co, Yellow Springs, OH). Plasma hemoglobin A_1c was measured by affinity chromatography using the Variant II system (Bio-Rad Laboratories, Hercules, CA).

Total cholesterol, triglyceride, and high-density lipoprotein cholesterol concentrations were measured enzymatically using an autoanalyzer (Hitachi 747, Hitachi, Ltd, Tokyo, Japan). The level of low-density lipoprotein cholesterol was calculated using the formula: LDL – Chol = TC – (HDL – Chol + TG/5) [6]. Hemoglobin concentration was measured by colorimetry using HST 403XE (SYSMEX, Japan). Other laboratory tests including creatinine and high-sensitivity C-reactive protein were performed using an autoanalyzer (Hitachi 747).

Preoperative Risk Evaluation
The preoperative risk prediction tool suggested by the Northern New England Cardiovascular Disease Study Group [7] was used to calculate a fatal low-output heart failure score for each group of patients.

CABG Procedure
CABG was performed by 3 cardiac surgeons (Drs Park, Choh, and Lim). The priority of the operation was assessed by the surgeons using definitions described previously [8]. Briefly, emergency means that the operation should be performed within hours because of the patient's status to prevent morbidity or death. Elective means that medical factors indicate the need for operation, but the patient's clinical situation allows discharge from the hospital with subsequent readmission. Urgent is neither elective nor emergency, meaning that medical factors require the patient to stay in the hospital for an operation before discharge to minimize further clinical deterioration. Operation time (defined as the time from skin incision to skin closure) and pump hours (length of time on a cardiopulmonary bypass) were recorded in all cases.

Documentation of Cardiac Status
An old myocardial infarction (MI) was defined when significant Q waves on preoperative electrocardiograms were observed, or regional wall akinesia on echocardiography, or persistent perfusion defects on single photon-emission CT, or more than 75% of subendocardial infarction on heart magnetic resonance imaging. Acute MI was defined as a MI that had occurred within 3 months preoperatively. Any history of percutaneous transluminal coronary angioplasty or previous CABG was reviewed using the medical records. Preoperative coronary artery disease status was classified as stable angina, unstable angina, or MI. The definitions of each condition were based on the Case Definitions for Acute Coronary Heart Disease established by the American Heart Association in 2003 [9]. Echocardiography (SONOS 7500, Philips Medical Systems Inc, Andover, MA) was used to measure preoperative left ventricular (LV) ejection fraction (EF) by the M-mode. Preoperative LV dysfunction was defined when the LVEF was less than 0.40.

Left main coronary artery disease was defined when more than 50% of intraluminal stenosis was observed by previous coronary angiography. Calcification of the ascending aorta was evaluated by routine preoperative CT angiography.

Outcomes
A major adverse cardiovascular event (MACE), including death, postoperative MI, an acute CVA, or acute renal failure, was considered a primary outcome. Postoperative complications other than MACE, defined as cardiac arrhythmia, wound problems, mediastinitis, leg infections, respiratory complications, delirium, or reoperation during the same hospitalization, were regarded as secondary outcomes. A postoperative MI was diagnosed by finding at least two of the following four criteria:

• prolonged (> 20 min) typical chest pain not relieved by rest or nitrates, or both;

• enzyme level elevation comprising creatine kinase MB exceeding 5% of total creatine kinase, creatine kinase greater than twice normal value, or troponin I exceeding 0.2 ng/mL;

• new wall motion abnormalities; or

• serial electrocardiograms (at least two) showing changes from baseline or serially in ST-T or Q waves, or both, that were 0.03 seconds or more in width or greater than one-third the height of the total QRS complex in two or more contiguous leads, or both.

Postoperative acute renal failure was diagnosed from serum creatinine levels, as already defined. Patients were routinely monitored postoperatively for the occurrence of arrhythmias by bedside monitors during intensive and intermediate care unit stay. Newly developed supraventricular and ventricular arrhythmias, including episodes within the first 24 hours of the operation, were documented from the rhythm strips on the electronic medical record of the patients. AF was documented when an irregularly irregular supraventricular rhythm was present in the absence of P waves. When needed, 12-lead electrocardiograms were obtained to determine the exact cardiac rhythm.

A respiratory complication was defined as prolonged ventilation, reintubation, or tracheostomy, or a diagnosis of culture-positive pneumonia. A re-event was defined as when a repeat operation or a percutaneous transluminal coronary angioplasty was needed because of recurring ischemic events.

Statistical Analysis
All data are expressed as the mean ± standard deviation or number (%). The ² and t tests were used to determine any statistically significant differences between groups. Binary logistic regression analysis was used to assess the risk of postoperative AF. A Hosmer-Lemeshow goodness of fit test was applied to assess the fit of logistic regression models. To reduce the effect of multicollinearity, we computed correlation coefficients of independent variables and confirmed that no pair of the independent variables had a value of more than 0.8. SPSS 12.0 software (SPSS Inc, Chicago, IL) was used for the analysis, and p < 0.05 was considered significant.

	Results

Top Abstract Introduction Patients and Methods Results Comment Footnotes References

 
Preoperative Characteristics
The prevalence of SCH in this study was 12.8% (Table 1). Mean age, body mass index, and gender distribution were similar between the two groups. Glycemic control variables and lipid profiles were similar in the two groups, but the SCH patients had hemoglobin levels of 12.2 ± 2.3 g/dL vs the euthyroid group at 13.0 ± 2.1 g/dL (p = 0.034). There were no significant differences in inflammatory markers or in serum creatinine levels according to thyroid function. Also similar were preoperative peak cardiac enzyme levels, which indicate the degree of myocardial damage by the coronary event.

Operation-Related Characteristics
Procedures were elective in 114 patients (50.9%) in the euthyroid group vs 20 (55.6%) in the SCH group, and less than 10% of patients underwent emergency operations (Table 2). However, thyroid status did not influence the selection for operation. The frequency of repeat operation was similar between euthyroid and SCH patients: 208 of 281 patients had isolated CABG and the remaining 52 underwent CABG with other major cardiovascular operations, which included CABG with the Dor procedure, with the Maze operation, and with valvular procedure. The proportion of patients undergoing CABG with other major cardiovascular operations was not different between groups. There were no significant differences between groups in the numbers of anastomoses, mean operation and pump times, or in the proportion undergoing on-pump CABG or needing intraaortic balloon pump assistance.

	Comment

Top Abstract Introduction Patients and Methods Results Comment Footnotes References

 
Preoperative SCH before CABG increased the risk of postoperative AF, even after adjusting for other possible risk factors, although it was not related to the risk of MACE, the primary outcome, and most of the postoperative AF was reversible at discharge. Postoperative AF occurs in 30% to 40% of patients undergoing CABG [11, 12]. Despite the improvement of anesthesia and surgical management, postoperative AF remains a relevant clinical problem in patients undergoing CABG, and the increasing number of pharmacologic and other strategies to prevent the onset of AF is a reflection of this [13]. AF can result in tachycardia, hypotension, heart failure, and a possible increase in the risk of a CVA [14]. It also increases medical costs and lengthens hospital stay [10, 15]. Factors associated with an increased risk of postoperative AF include age, male gender, operation for valvular heart disease, use of cardiopulmonary bypass, preoperative nonuse of β-blockers, chronic obstructive lung disease, and right coronary artery stenosis, even though the factors suggested by the individual studies differ [12, 16–18].

Our study found that even after adjusting for these risk factors, postoperative AF was more frequent in patients with SCH. Although we observed no increase in the incidence of CVA, postoperative AF, and hospital stay, we cannot deny that SCH might affect postoperative outcome by increasing the incidence of postoperative AF in patients undergoing CABG.

The cardiovascular system is one of the major target organs of thyroid hormone [1, 19]. The most prominent changes seen in hypothyroid patients are increased systemic vascular resistance and impaired cardiac pump performance [1, 5, 19]. Endothelial dysfunction, altered blood coagulability, and increased levels of C-reactive protein also provide evidence for the deleterious effects of hypothyroidism on the cardiovascular system [5, 20]. SCH can also have repercussions on the cardiovascular system [21]. However, in the context of the known association between chronic hyperthyroidism and AF, our finding that SCH was associated with postoperative AF in this series is somewhat unexpected. Although the exact mechanism of the relationship between SCH and AF is difficult to explain, the association between low T3 levels and postoperative AF in patients undergoing cardiac operations has been reported [22, 23]. It is well known that patients undergoing cardiac procedures have low free T3 levels, which is called the "low T3 syndrome" [24]. Decreased cardiac 5'-monodeiodinase activity, which reduces the peripheral conversion of T4 to T3, and the use of cardiopulmonary bypass, which alters cardiocirculatory physiology, might contribute to this condition [25–27].

The cause of AF in patients with a low T3 level is unknown; however, a potential explanation was suggested from the results of in vitro studies. In a low T3 state, Ca²⁺ load inside the intracellular compartment is reduced by depressed activity of Ca²⁺ adenosine triphosphatase of the sarcoplasmic reticulum in human cardiomyocytes, and a reduction in the L-type Ca²⁺ current has been described in the ventricular myocytes of hypothyroid guinea pigs. Reduced intracellular calcium load is a phenomenon that observed in arrhythmogenic ionic remodeling, and reduction in the L-type Ca²⁺ current is a figure that has been reported in animal and human models of AF [23]. T3 also has important effects on the ionic current of cardiomyocytes during the action potential [28]. Furthermore, the administration of exogenous T3 was reported to reduce the incidence of AF in patients undergoing CABG [29]. With these findings, it seems to be consistent that low thyroid hormonal status is likely to be related to the incidence of AF. We assume that the low T3 state can be more profound in patients with SCH, so postoperative AF is likely to develop more frequently. To verify the mechanism of SCH affecting postoperative AF, however, more studies are needed on the causes of postoperative AF as well as for the potential sites at which thyroid hormone could modify its development.

There have been several trials to replace T3 before or after CABG, but T3 or T4 treatment before CABG does not seem to be beneficial for hemodynamic or prognostic variables [26, 27, 30, 31]. However, because SCH seemed to increase the incidence of postoperative AF in our study and there is a report that correction of a hypothyroid status can reduce it [28], further study will be needed to verify any benefit of thyroid hormone replacement.

Detailed preoperative and postoperative evaluations as well as the prospective study design comprise the strength of this study reporting the effect of SCH on the outcome for patients undergoing CABG. Some limitations need to be addressed, however. Groups with subclinical thyroid dysfunction showed a trend to have more postoperative complications than did euthyroid patients, but this was not statistically significant, perhaps because our study was conducted on a relatively small number of patients.

In addition, preoperative and postoperative T3 and free T3 levels were not measured, so that we could not verify if patients with SCH experienced a more severe "low T3 syndrome" postoperatively, which could be a possible explanation of the increased postoperative incidence of AF in patients with SCH. Without measuring thyroid autoantibodies, we could not identify the cause of SCH in individual patients and could not differentiate the effects of each cause on the development of postoperative AF.

In summary, the incidence of transient postoperative AF was significantly higher in patients with SCH. Although the incidence of a major MACE such as stroke, acute renal failure, death, or postoperative MI was not elevated in patients with SCH, our results indicate that preoperative SCH might have a significant effect on CABG outcome when we consider the hemodynamic effects of transient AF on patients undergoing CABG. Therefore, we suggest that the detection of preoperative thyroid dysfunction or the routine assessment of thyroid function might be important for such patients. A larger study is needed to determine whether thyroid hormone replacement preoperatively or administration of T3 during the operation would be truly beneficial.

	Footnotes

Top Abstract Introduction Patients and Methods Results Comment Footnotes References

 
^_* These authors equally contributed to this work.

	References

Top Abstract Introduction Patients and Methods Results Comment Footnotes References

 

1. Fazio S, Palmieri EA, Lombardi G, Biondi B. Effects of thyroid hormone on the cardiovascular system Recent Prog Horm Res 2004;59:31-50.[Abstract/Free Full Text]
2. Biondi B, Fazio S, Palmieri EA, et al. Left ventricular diastolic dysfunction in patients with subclinical hypothyroidism J Clin Endocrinol Metab 1999;84:2064-2067.[Abstract/Free Full Text]
3. Ripoli A, Pingitore A, Favilli B, et al. Does subclinical hypothyroidism affect cardiac pump performance? Evidence from a magnetic resonance imaging study J Am Coll Cardiol 2005;45:439-445.[Abstract/Free Full Text]
4. Iervasi G, Pingitore A, Landi P, et al. Low-T3 syndrome: a strong prognostic predictor of death in patients with heart disease Circulation 2003;107:708-713.[Abstract/Free Full Text]
5. Biondi B, Klein I. Hypothyroidism as a risk factor for cardiovascular disease Endocrine 2004;24:1-13.[Medline]
6. Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge Clin Chem 1972;18:499-502.[Abstract/Free Full Text]
7. Surgenor SD, O'Connor GT, Lahey SJ, et al. Predicting the risk of death from heart failure after coronary artery bypass graft surgery Anesth Analg 2001;92:596-601.[Abstract/Free Full Text]
8. O'Connor GT, Plume SK, Olmstead EM, et al. A regional prospective study of in-hospital mortality associated with coronary artery bypass grafting. The Northern New England Cardiovascular Disease Study Group. JAMA 1991;266:803-809.[Abstract/Free Full Text]
9. Luepker RV, Apple FS, Christenson RH, et al. Case definitions for acute coronary heart disease in epidemiology and clinical research studies: a statement from the AHA Council on Epidemiology and Prevention; AHA Statistics Committee; World Heart Federation Council on Epidemiology and Prevention; the European Society of Cardiology Working Group on Epidemiology and Prevention; Centers for Disease Control and Prevention; and the National Heart, Lung, and Blood Institute Circulation 2003;108:2543-2549.[Free Full Text]
10. Tamis JE, Steinberg JS. Atrial fibrillation independently prolongs hospital stay after coronary artery bypass surgery Clin Cardiol 2000;23:155-159.[Medline]
11. Hogue Jr CW, Hyder ML. Atrial fibrillation after cardiac operation: risks, mechanisms, and treatment Ann Thorac Surg 2000;69:300-306.[Abstract/Free Full Text]
12. Hill LL, Kattapuram M, Hogue Jr CW. Management of atrial fibrillation after cardiac surgery–part I: pathophysiology and risks J Cardiothorac Vasc Anesth 2002;16:483-494.[Medline]
13. Crystal E, Connolly SJ, Sleik K, Ginger TJ, Yusuf S. Interventions on prevention of postoperative atrial fibrillation in patients undergoing heart surgery: a meta-analysis Circulation 2002;106:75-80.[Abstract/Free Full Text]
14. Ommen SR, Odell JA, Stanton MS. Atrial arrhythmias after cardiothoracic surgery N Engl J Med 1997;336:1429-1434.[Medline]
15. Steinberg JS. Postoperative atrial fibrillation: a billion-dollar problem J Am Coll Cardiol 2004;43:1001-1003.[Free Full Text]
16. Auer J, Weber T, Berent R, Ng CK, Lamm G, Eber B. Risk factors of postoperative atrial fibrillation after cardiac surgery J Card Surg 2005;20:425-431.[Medline]
17. Creswell LL, Alexander Jr JC, Ferguson Jr TB, Lisbon A, Fleisher LA. Intraoperative interventions: American College of Chest Physicians guidelines for the prevention and management of postoperative atrial fibrillation after cardiac surgery Chest 2005;128:28S-35S.[Medline]
18. Ascione R, Caputo M, Calori G, Lloyd CT, Underwood MJ, Angelini GD. Predictors of atrial fibrillation after conventional and beating heart coronary surgery: a prospective, randomized study Circulation 2000;102:1530-1535.[Abstract/Free Full Text]
19. Klein I, Ojamaa K. Thyroid hormone and the cardiovascular system N Engl J Med 2001;344:501-509.[Medline]
20. Cappola AR, Ladenson PW. Hypothyroidism and atherosclerosis J Clin Endocrinol Metab 2003;88:2438-2444.[Free Full Text]
21. Biondi B, Cooper DS. The clinical significance of subclinical thyroid dysfunction Endocr Rev 2008;29:76-131.[Abstract/Free Full Text]
22. Kokkonen L, Majahalme S, Koobi T, et al. Atrial fibrillation in elderly patients after cardiac surgery: postoperative hemodynamics and low postoperative serum triiodothyronine J Cardiothorac Vasc Anesth 2005;19:182-187.[Medline]
23. Cerillo AG, Bevilacqua S, Storti S, et al. Free triiodothyronine: a novel predictor of postoperative atrial fibrillation Eur J Cardiothorac Surg 2003;24:487-492.[Abstract/Free Full Text]
24. Broderick TJ, Wechsler AS. Triiodothyronine in cardiac surgery Thyroid 1997;7:133-137.[Medline]
25. Salter DR, Dyke CM, Wechsler AS. Triiodothyronine (T3) and cardiovascular therapeutics: a review J Card Surg 1992;7:363-374.[Medline]
26. Klemperer JD, Klein I, Gomez M, et al. Thyroid hormone treatment after coronary-artery bypass surgery N Engl J Med 1995;333:1522-1527.[Medline]
27. Teiger E, Menasche P, Mansier P, et al. Triiodothyronine therapy in open-heart surgery: from hope to disappointment Eur Heart J 1993;14:629-633.[Abstract/Free Full Text]
28. Bosch RF, Wang Z, Li GR, et al. Electrophysiological mechanisms by which hypothyroidism delays repolarization in guinea pig hearts Am J Physiol 1999;277:211-220.
29. Klemperer JD, Klein IL, Ojamaa K, et al. Triiodothyronine therapy lowers the incidence of atrial fibrillation after cardiac operations Ann Thorac Surg 1996;61:1323-1327discussion 1328–9.[Abstract/Free Full Text]
30. Ranasinghe AM, Quinn DW, Pagano D, et al. Glucose-insulin-potassium and tri-iodothyronine individually improve hemodynamic performance and are associated with reduced troponin I release after on-pump coronary artery bypass grafting Circulation 2006;114:I245-I250.[Medline]
31. Sirlak M, Yazicioglu L, Inan MB, et al. Oral thyroid hormone pretreatment in left ventricular dysfunction Eur J Cardiothorac Surg 2004;26:720-725.[Abstract/Free Full Text]

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Young Joo Park Kwang Il Kim Kyung Won Kim Joong Haeng Choh Cheong Lim Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Park, Y. J. Articles by Lim, C. Search for Related Content PubMed PubMed Citation Articles by Park, Y. J. Articles by Lim, C. Related Collections Electrophysiology - arrhythmias