Normalization of peripheral thyroid hormone metabolism induced by successful chronic amiodarone treatment in patients with ventricular arrhythmias

Non-Thyroidal Illness Syndrome-Associated Multiorgan Dysfunction After Surgical Repair of Type A Aortic Dissection

OBJECTIVE

The purpose of this cohort study was to investigate the relationship between non-thyroidal illness syndrome (NTIS) and severe multiorgan dysfunction, measured by Sequential Organ Failure Assessment score ≥11, after surgical repair of type A aortic dissection (TAAD).

SETTING

An observational study.

PARTICIPANTS

The present study included 310 patients with TAAD surgically repaired between January 2019 and December 2020 in Beijing Anzhen Hospital.

INTERVENTIONS

Patients after surgical repair after TAAD.

MEASUREMENTS AND MAIN RESULTS

Among a total of 310 patients with TAAD undergoing surgical repair included in this study, 132 (42.6%) experienced surgery-associated NTIS. Severe multiorgan dysfunction was experienced more often in patients with NTIS (27.3% v 11.2%, p < 0.0001). Multivariate analysis demonstrated NTIS was associated closely with an increased risk of severe multiorgan dysfunction (odds ratio [OR] = 2.54, 95% CI = 1.39-4.64 p = 0.002), which predicted an in-hospital death rate of 95%. Non-thyroidal illness syndrome also was related with in-hospital major adverse cardiovascular and cerebral events (OR = 2.12, 95% CI = 1.30-3.46 p = 0.003), acute kidney injury (OR = 3.17, 95% CI = 1.17-8.47 p = 0.023), and postoperative pulmonary complications (OR = 2.32, 95% CI = 1.34-4.03 p = 0.003). However, hepatic inadequacy was comparable in the NTIS and control groups.

CONCLUSIONS

Non-thyroidal illness syndrome was associated closely with multiorgan dysfunction after surgical repair of TAAD, which may be correlated further with an increased incidence of in-hospital mortality and complications.

Low Free Triiodothyronine at Admission Predicts Poststroke Infection

BACKGROUND

Poststroke infection (PSI) is common and is usually associated with a severe prognosis. We investigated the association between PSI and thyroid hormones, which are critical to immune regulation, in patients with acute stroke.

METHODS

We retrospectively enrolled 520 consecutive patients with acute ischemic stroke (326 men; age, 71.9 ± 13.2 years) admitted to our department between September 2014 and June 2016. The impact of serum thyroid hormone levels measured at admission (thyroid-stimulating hormone [TSH], free triiodothyronine [FT3], and free thyroxine [FT4]) on the PSI was evaluated using multivariate logistic regression analysis.

RESULTS

We diagnosed 107 patients (20.6%; pneumonia, 65; urinary tract infection, 19; others, 23) with PSIs. While age (P <.001), body mass index (P = .0012), preadmission modified Rankin scale score (P = .0001), National Institutes of Health Stroke Scale score on admission (P <.001), admission FT3 level (P <.001), atrial fibrillation (P <.001), and ischemic heart disease (P = .0451) were significantly associated with PSI, we found no relationship among TSH levels, FT4 levels, and PSI occurrence. After multivariate adjustment, patients with PSIs were more frequently in the Q1 quartile (≤2.25 pg/mL) than in the Q2 (2.26-2.55 pg/mL; P = .0251), Q3 (2.56-2.89 pg/mL; P = .0007), or Q4 (≥2.90 pg/mL; P = .0010) quartiles of FT3 levels. Moreover, low FT3 levels (<2.29 pg/mL) were independently associated with PSI occurrence (P = .0013).

CONCLUSIONS

Low FT3 levels at admission are independently associated with PSI occurrence.

Amiodarone inhibits the 3,5,3'-triiodothyronine-dependent increase of sodium/potassium adenosine triphosphatase activity and concentration in human atrial myocardial tissue

In animal models the function of the sodium pump (sodium/potassium-adenosine triphosphatase [Na+/K(+)-ATPase]) is enhanced by 3,5,3'-triiodothyronine (T3) and inhibited by the antiarrhythmic agent amio. However, it is still unclear whether the effect of the drug on Na+/K(+)-ATPase depends on the interference with thyroid hormone action. We evaluated the interaction of T3 with amiodarone on Na+/K(+)-ATPase activity and site number in human myocardium. Right atrial slices were cultured with (T3+) and without (T3-) 3 nM T3 in presence and absence of amiodarone at therapeutical dose (1.5 microM). When compared to T3+, T3- preparations showed decreased 3H-ouabain binding (p < 0.004) and lower 20-minute and 45-minute 86Rb-uptake (p < or = 0.004). Amiodarone caused an average 49% reduction of the T3-dependent 3H-ouabain binding and decreased the Western blot signal for the Na+/K(+)-ATPase alpha1 subunit. The drug also inhibited T3-dependent increase in 86Rb-influx at 20 and 45 minutes by 66% and 42%, respectively, without affecting the affinity of the pump for K+. No differences were found in the 3H-ouabain binding and 86Rb-uptake of T3-, T3- amio and T3(+)-amio. In conclusion, T3 stimulates the Na+/K(+)-ATPase in human atrial myocardium by increasing the number of ouabain-binding sites, whereas amiodarone decreases the sodium pump function secondarily to the antagonism with thyroid hormone.

Low-T3 syndrome: a strong prognostic predictor of death in patients with heart disease

BACKGROUND

Clinical and experimental data have suggested a potential negative impact of low-T3 state on the prognosis of cardiac diseases. The aim of the present prospective study was to assess the role of thyroid hormones in the prognosis of patient population with heart disease.

METHODS AND RESULTS

A total of 573 consecutive cardiac patients underwent thyroid function profile evaluation. They were divided in two subgroups: group I, 173 patients with low T3, ie, with free T3 (fT3) <3.1 pmol/L, and group II, 400 patients with normal fT3 (>or=3.1 pmol/L). We considered cumulative and cardiac death events. During the 1-year follow-up, there were 25 cumulative deaths in group I and 12 in group II (14.4% versus 3%, P<0.0001); cardiac deaths were 13 in group I and 6 in group II (7.5% versus 1.5%, P=0.0006). According to the Cox model, fT3 was the most important predictor of cumulative death (hazard ratio [HR] 3.582, P<0.0001), followed by dyslipidemia (HR 2.955, P=0.023), age (HR 1.051, P<0.005), and left ventricular ejection fraction (HR 1.037, P=0.006). At the logistic multivariate analysis, fT3 was the highest independent predictor of death (HR 0.395, P=0.003). A prevalence of low fT3 levels was found in patients with NYHA class III-IV illness compared with patients with NYHA class I-II (chi(2) 5.65, P=0.019).

CONCLUSIONS

Low-T3 syndrome is a strong predictor of death in cardiac patients and might be directly implicated in the poor prognosis of cardiac patients.

Nonthyroidal illness syndrome in off-pump coronary artery bypass grafting

BACKGROUND

Cardiopulmonary bypass (CPB) is an established cause of nonthyroidal illness syndrome (NTIS). Off-pump coronary artery bypass (OPCAB) has been reported to be less invasive than coronary artery bypass grafting (CABG) with CPB. We prospectively evaluated thyroid metabolism in OPCAB patients.

METHODS

We analyzed free thyroid hormones (FT3 and FT4), thyroid-stimulating hormone (TSH), and reverse T3 (rT3) in 20 consecutive patients undergoing CABG surgery. Nine patients underwent CABG with CPB, and 11 underwent OPCAB. Blood samples were taken on admission, on the day of surgery (7:30 AM), after sternotomy, at the end of the operation, and at 2, 6, 12, 24, 36, 48, 72, 96, 120, and 144 hours postoperatively. The concentrations of FT3, FT4, and TSH were determined on each sample. Reverse T3 concentration was measured in 10 patients up to 48 hours and at 144 hours postoperatively.

RESULTS

Baseline, operative, and postoperative variables were similar in the two groups. FT3 concentration dropped significantly (p < 0.0001), reaching its lowest value 12 hours postoperatively. There were no significant differences between CPB and OPCAB patients. FT4 varied significantly in both groups (p < 0.0001), but remained in the normal range. TSH variation was not significant. rT3 concentration rose significantly (p = 0.0002) in both groups, peaking 24 hours after surgery. CONCLUSIONS. OPCAB induces a NTIS similar to that observed after CPB, probably due to the inhibition of T4 conversion to T3. This finding suggests that NTIS is a nonspecific response to stress. CPB should not be considered as the sole trigger of NTIS in cardiac surgical patients.

The role of thyroid hormone in blood pressure homeostasis: evidence from short-term hypothyroidism in humans

Arterial hypertension is known to be frequently associated with thyroid dysfunction, with a particularly high prevalence in chronic hypothyroidism. However, to our knowledge no comprehensive study addressed causal mechanisms possibly involved in this association. We here report the physiological relationships between blood pressure and neuro-humoral modifications induced by acute hypothyroidism in normotensive subjects. Twelve normotensive patients with previous total thyroidectomy were studied. Ambulatory 24-h blood pressure monitoring was performed, and free T(3), free T(4), TSH, PRA, aldosterone, cortisol, adrenaline, and noradrenaline were assayed 6 wk after oral L-T(4) withdrawal (phase 1) and 2 months after resumption of treatment (phase 2). During the hypothyroid state (TSH, 68.1 +/- 27.7 microIU/ml; mean +/- SD), daytime arterial systolic levels slightly, but significantly, increased (125.5 +/- 9.7 vs. 120.4 +/- 10.8 mm Hg; P < 0.05), and daytime diastolic levels (84.6 +/- 7.9 vs. 76.4 +/- 6.8 mm Hg; P < 0.001), noradrenaline (2954 +/- 1578 vs. 1574 +/- 962 pmol/liter; P < 0.001), and adrenaline (228.4 +/- 160 vs. 111.3 +/- 46.1 pmol/liter; P < 0.05) also increased. PRA remained unchanged (0.49 +/- 0.37 vs. 0.35 +/- 0.21 ng/ml.h; P = NS), whereas both aldosterone (310.3 +/- 151 vs. 156.9 +/- 67.5 pmol/liter; P < 0.005) and cortisol (409.2 +/- 239 vs. 250.9 +/- 113 pmol/liter; P < 0.02) significantly increased. By using univariate logistic regression daytime arterial diastolic values, noradrenaline and aldosterone were found to be significantly related to the hypothyroid state (P < 0.02, P < 0.036, and P < 0.024, respectively). In conclusion, our data show that thyroid hormones participate in the control of systemic arterial blood pressure homeostasis in normotensive subjects. The observed sympathetic and adrenal activation in hypothyroidism, which is reversible with thyroid hormone treatment, may also contribute to the development of arterial hypertension in human hypothyroidism.

Hyperthyroidism is associated with lengthening of ventricular repolarization

OBJECTIVE

Lengthened ventricular repolarization, as assessed by the QT interval on electrocardiogram (ECG), can predispose to an increased risk of cardiac dysrhythmias; no data are available on QT corrected for heart rate (QTc) in hyperthyroidism in vivo.

DESIGN

QT and RR intervals from 24 h ambulatory ECG Holter recording were measured in patients with hyperthyroidism and again following pharmacological achievement of stable euthyroidism for at least 2 months.

PATIENTS

We enrolled a total of 16 hyperthyroid patients with Graves' disease, six males and 10 females (mean age 47 +/- 4 years, mean +/- SEM); 13 healthy age- and sex-matched subjects were utilized as a control group.

MEASUREMENTS

The QT analysis was carried out by a computerized algorithm (QTc was corrected by the heart rate by Bazett's formula). Serum total T4, total T3, free T4, free T3 and TSH concentrations were measured by a fully automated immunoenzymometric assay; plasma norepinephrine by automatized high-pressure liquid chromatography, potassium and chloride by a potentiometric method, magnesium and calcium by a colourimetric method.

RESULTS

The 24-h average QTc in the hyperthyroid patients was significantly prolonged compared to controls (458 +/- 7 vs. 431 +/- 6 ms, P = 0.01) and it returned to normal after treatment of thyrotoxicosis (432 +/- 6 ms, P < 0.05 vs. time H, NS vs. controls). QTc positively correlated with FT3 (r = 0.63, P < 0.001) and with FT4 (r = 0.481, P < 0.02). Conversely, QTc did not correlate with plasma basal norepinephrine levels, nor with electrolytes.

CONCLUSIONS

Hyperthyroidism is associated with prolonged QTc that normalizes once the patient becomes euthyroid. The strong positive correlation between FT3 and QTc supports the hypothesis of an important role of thyroid hormone on modulation of QTc lengthening.