Role of Levothyroxine Supplementation in Delayed Recovery Following Cardiac Surgery

NCT ID: NCT06660823

Last Updated: 2025-08-17

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: PHASE3
• Total Enrollment: 70 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2024-11-30
• Study Completion Date: 2025-06-25

Brief Summary

Research indicates that hypothyroidism decreases heart contractility, reduces stroke volume and rate, affects the vascular endothelium, and increases the risk of atherosclerosis, systemic vascular resistance, hypertension, atherogenic lipid profile, and coagulation abnormality .

Hypothyroidism was reported to be strongly related to cardiovascular disease, respiratory complications, neurological complications, and a significant difference in ventilator weaning time.

Once subclinical hypothyroidism patients are treated with levothyroxine, their physical fitness measured by a 6-minute walk is significantly improved, also showed that levothyroxine treatment can optimize the treatment of heart failure with preserved functions (HFpEF) and heart failure with reduced functions (HFrEF) patients with systolic left ventricular dysfunction and sub clinical hypothyroidism (SCH).

The primary aim of this study is to investigate the effect of supplementation of oral levothyroxine in delayed recovery patients post cardiac surgery.

Detailed Description

Research indicates that hypothyroidism decreases heart contractility, reduces stroke volume and rate, affects the vascular endothelium, and increases the risk of atherosclerosis, systemic vascular resistance, hypertension , atherogenic lipid profile, and coagulation abnormality .

Hypothyroidism was reported to be strongly related to cardiovascular disease, respiratory complications, neurological complications, and a significant difference in ventilator weaning time. Severe thyroid dysfunction is related to muscle relaxation and lead to respiratory muscle depression and disturbed conscious level.Surgical stress of cardiac surgery might be followed by a prolonged recovery process and cardiac dysfunction .

The exact physiology of thyroid disease and the relationship with post cardiac surgery remain unclear. Thus far, large-scale clinical statistical analysis evidence on the complication rate and long-term mortality is lacking. Current important prognostic assessment tools such as EuroSCORE II , and Society of Thoracic Surgeons (STS) score do not include thyroid function assessment, even though it has a significant impact on the metabolic, cardiovascular, and circulation system.

Once subclinical hypothyroidism patients are treated with levothyroxine, their physical fitness measured by a 6-minute walk is significantly improved, also showed that levothyroxine treatment can optimize the treatment of heart failure with preserved functions (HFpEF) and heart failure with reduced functions (HFrEF) patients with systolic left ventricular dysfunction and sub clinical hypothyroidism (SCH).

The heart is a major target of thyroid hormones, with maintenance of euthyroid hormone balance critical for proper function. Moreover, thyroid hormones have been shown a vital role in cardiac repair after injury beyond their roles in development and metabolism homeostasis.

After cardiac surgery with cardiopulmonary bypass (CPB), however, serum thyroid hormone levels are often decreased, especially in pediatric patients. This is called as the euthyroid sick syndrome (ESS).

It is reported that after cardiac surgery with CPB, 50% to 75% of adult patients present a decreased serum level of triiodothyronine (T3) (type 1 ESS) and 100% of pediatric patients display decreased serum levels of both T3 and tetraiodothyronine (T4) (type 2 ESS).

Because ESS has been associated with increased morbidity after cardiac surgery, it is deemed that intravenous supplementation of thyroid hormones in postoperative period is benefit to infants and small children. This view is supported by the largest randomized clinical trial so far, the Triiodothyronine for Infants and Children Undergoing CPB (TRICC) study, in which subgroup analysis shows a significant reduction in mechanical ventilation time, less use of inotropic drugs, and better cardiac function with intravenous T3 supplementation after surgery in pediatric patients aged <5 months.

Ischemia and reperfusion occur during almost every cardiac surgery and myocardial ischemia/reperfusion injury (IRI) is an important cause of morbidity and mortality in the early postoperative period after cardiac surgery. It has been shown that thyroid hormones can limit myocardial IRI via a fine balance between proapoptotic and prosurvival signaling pathways.Furthermore, thyroid hormones can provide a protection against myocardial IRI by inducing pharmacological preconditioning.The available evidence also indicates that perioperative oral T3 therapy can significantly attenuate the postoperative decline in serum T3 level or maintain total and free serum T3 levels within normal limits in adult and pediatric patients undergoing cardiac surgery.Given that oral administration is a safe, convenient and feasible route of perioperative medication. This has been proven by the single-center, prospective, double blind, randomized placebo-controlled clinical pilot trial including 40 patients receiving a dose of 0.4mg/kg (trial group, thyroid tablet taken orally once a day, for 4 days before surgery).In summary, this pilot study demonstrated that children after cardiac surgery with CPB are at a high risk to develop postoperative ESS. Preoperatively short-term oral thyroid hormones can reduce severity of postoperative ESS without negative effects and provides a protection against myocardial IRI by increasing HSP70 and MHCa expression.

In another reported double blind, placebo-controlled trial in 100 infants with normal thyroid function. Subjects underwent cardiac surgery and were randomly assigned during a 16-month period into 2 groups (50 in the thyroxine supplementation group and 50 in the placebo group) to determine whether there was an association between oral thyroxine (T4) supplementation and changes in cardiac index (CI), along with other important outcomes. Subjects in the study group received an oral dose of 5 µg/kg of T4 starting 12 hours before surgery and every morning thereafter while in the intensive care unit. Subjects in the study group had higher CI than did the placebo group (CI 0.30 L/min/m2 higher; P = .04).

It has been well described that early after the initiation of CPB, particularly DHCA, thyroid-stimulating hormone concentration is raised, responding to decreased concentrations of triiodothyronine (T3), and that levels restore during a period of days, beginning with thyroid stimulating hormone and followed by T3, an entity referred as ''euthyroid sick syndrome.'' An actual etiology for these changes has not been precisely described; however, hemodilution, hypothermia, and inflammation have been implicated. As of now, thyroid hormone supplementation remains the mainstay therapy for euthyroid sick syndrome.

This study , like several others, demonstrates that perioperative thyroid hormone supplementation is associated with improved outcomes. They demonstrated that Thyroid hormone levels are reduced significantly in the immediate postoperative period after open-heart surgery. Oral T4 supplementation improves the CI and reduces the inotropic requirement. In addition, it reduces the duration of mechanical ventilation, ICU and hospital stay, and TISS in infants after surgery for complex congenital heart defects.

Routinely, patients with delayed recovery and/or prolonged mechanical ventilation are managed as follow :

1. Full neurological examination, CT brain, repeated CT brain after 48-hour, MRI stroke protocol, adding of brain stimulants medications and if fits developed antiepileptics would be added accordingly.

2. Liver profile checked and liver support added,

3. Renal profile checked, stoppage of nephrotoxic drugs, fluids chart, renal dose adjustment of medications.

4. Blood sugar hourly monitored.

5. Sepsis surveillance by withdrawing pan cultures, replacing old IV catheters upgrading antibiotics accordingly.

This is typically included in institutional ICU protocol. The primary aim of this study is to investigate the effect of supplementation of oral levothyroxine in delayed recovery patients post cardiac surgery.

Conditions

Cardiac Surgery Intensive Care Treatment; Delayed Recovery From Anaesthesia; Euthyroid Sick Syndrome; Cardiac Surgery Requiring Cardiopulmonary Bypass

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: DOUBLE

Study Groups

Group A (Study group)

group A will receive levothyroxine via Ryle, dose of 25 to 50 ug/ day according to BMI

Group Type: ACTIVE_COMPARATOR

L-thyroxine

Intervention Type: DRUG

Patients who show signs of delayed recovery defined as either prolonged ventilation for 48 hours or delayed conscious level recovery for 48 hours despite exclusion of muscle relaxants and/or sedative drugs. Those patients will undergo CT brain, CT chest and neurological examination to exclude structural damage as per institutional protocols. Also, metabolic profile screening including full kidney function, full liver function, electrolyte to exclude correctable metabolic abnormalities. and thyroid profile (TSH, free T3, free T4) sick euthyroid patients who are having normal FreeT3, normal Free T4, low TSH and low level of free T3 or freeT4 will be included in the study according lab reference.Daily assessment of conscious level according to Glasgow Coma Scale (GCS) and spontaneous breathing trial by ICU consultant (the investigator) till ICU discharge.

Patients will receive levothyroxine via Ryle, dose of 25 to 50 ug/ day according to BMI.

Group B (Control)

group B will receive placebo in form of inert starch tablet

Group Type: PLACEBO_COMPARATOR

Placebo Oral Tablet

Intervention Type: DRUG

patients will receive placebo oral tablet

Interventions

L-thyroxine

Patients who show signs of delayed recovery defined as either prolonged ventilation for 48 hours or delayed conscious level recovery for 48 hours despite exclusion of muscle relaxants and/or sedative drugs. Those patients will undergo CT brain, CT chest and neurological examination to exclude structural damage as per institutional protocols. Also, metabolic profile screening including full kidney function, full liver function, electrolyte to exclude correctable metabolic abnormalities. and thyroid profile (TSH, free T3, free T4) sick euthyroid patients who are having normal FreeT3, normal Free T4, low TSH and low level of free T3 or freeT4 will be included in the study according lab reference.Daily assessment of conscious level according to Glasgow Coma Scale (GCS) and spontaneous breathing trial by ICU consultant (the investigator) till ICU discharge.

Patients will receive levothyroxine via Ryle, dose of 25 to 50 ug/ day according to BMI.

Intervention Type: DRUG

Placebo Oral Tablet

patients will receive placebo oral tablet

Intervention Type: DRUG

Eligibility Criteria

Inclusion Criteria

• • Age group: Adult patients from age of 45 to70 years. (Majority of our patients falls in this age group 45-70 years, below these patients are relatively young and usually do not show delayed recovery or prolonged ventilation, while above 70 years are considered frail and more vulnerable to anesthetic medications, so we preferred to exclude them)

• Sex: Both sexes
• Elective, urgent and emergency open heart surgeries. (Most of urgent and emergency cases are either mechanical valve thrombosis or aortic dissection patients, and are more prone to prolonged mechanical ventilation and delayed recovery compared to elective patients)

Exclusion Criteria

• • Patients refuse to give informed consent.

• Patient younger than 45 years old, older than 70 years old.
• Off pump patients.
• Patients known hypothyroidism on levothyroxine supplementation.
• Patients known hyperthyroidism on Carbimazole.
• Those developing any form of arrhythmia L-Thyroxine will be stopped immediately and the patient will be excluded from the study.

• Minimum Eligible Age: 45 Years
• Maximum Eligible Age: 70 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Ain Shams University

OTHER

Sponsor Role: lead

Responsible Party

sarah hamdy

Lecturer of Anesthesia,ICU and pain management

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

Faculty of Medicine ,Ain Shams University

Cairo, , Egypt

Countries

Egypt

References

Duntas LH, Jonklaas J. Levothyroxine Dose Adjustment to Optimise Therapy Throughout a Patient's Lifetime. Adv Ther. 2019 Sep;36(Suppl 2):30-46. doi: 10.1007/s12325-019-01078-2. Epub 2019 Sep 4.

Reference Type: BACKGROUND

PMID: 31485977 (View on PubMed)

Flores S, Checchia PA. Inflammatory and neurohormonal modulation for congenital heart surgery: The quest continues. J Thorac Cardiovasc Surg. 2018 Sep;156(3):1207-1208. doi: 10.1016/j.jtcvs.2018.06.004. Epub 2018 Jun 22. No abstract available.

Reference Type: BACKGROUND

PMID: 30005886 (View on PubMed)

Batra YK, Singh B, Chavan S, Chari P, Dhaliwal RS, Ramprabu K. Effects of cardiopulmonary bypass on thyroid function. Ann Card Anaesth. 2000 Jul;3(2):3-6.

Reference Type: BACKGROUND

PMID: 17848764 (View on PubMed)

Zhang JQ, Yang QY, Xue FS, Zhang W, Yang GZ, Liao X, Meng FM. Preoperative oral thyroid hormones to prevent euthyroid sick syndrome and attenuate myocardial ischemia-reperfusion injury after cardiac surgery with cardiopulmonary bypass in children: A randomized, double-blind, placebo-controlled trial. Medicine (Baltimore). 2018 Sep;97(36):e12100. doi: 10.1097/MD.0000000000012100.

Reference Type: BACKGROUND

PMID: 30200092 (View on PubMed)

Kumar A, Taliyan R, Sharma PL. Evaluation of thyroid hormone induced pharmacological preconditioning on cardiomyocyte protection against ischemic-reperfusion injury. Indian J Pharmacol. 2012 Jan;44(1):68-72. doi: 10.4103/0253-7613.91870.

Reference Type: BACKGROUND

PMID: 22345873 (View on PubMed)

Plumpton K, Haas NA. Identifying infants at risk of marked thyroid suppression post-cardiopulmonary bypass. Intensive Care Med. 2005 Apr;31(4):581-7. doi: 10.1007/s00134-004-2549-1. Epub 2005 Jan 28.

Reference Type: BACKGROUND

PMID: 15678312 (View on PubMed)

Gerdes AM, Ojamaa K. Thyroid Hormone and Cardioprotection. Compr Physiol. 2016 Jun 13;6(3):1199-219. doi: 10.1002/cphy.c150012.

Reference Type: BACKGROUND

PMID: 27347890 (View on PubMed)

Biondi B, Klein I. Hypothyroidism as a risk factor for cardiovascular disease. Endocrine. 2004 Jun;24(1):1-13. doi: 10.1385/ENDO:24:1:001.

Reference Type: BACKGROUND

PMID: 15249698 (View on PubMed)

Provided Documents

Document Type: Study Protocol and Statistical Analysis Plan

View Document

Other Identifiers

FMASU R237/2024

Identifier Type: -

Identifier Source: org_study_id