Subclinical hyperthyroidism and biatrial function and mechanics: a two- and three-dimensional echocardiographic study

Association of Thyroid Dysfunction in Individuals ≥ 65 Years of Age With Subclinical Cardiac Abnormalities

CONTEXT

The relationship between thyroid dysfunction and measures of myocardial disease in older individuals remains to be defined.

OBJECTIVE

To evaluate the impact of thyroid dysfunction on structure and function of the left heart chambers and blood markers of cardiac disease.

METHODS

Cross-sectional analysis of the Cardiovascular Health Study, a community-based cohort of older individuals recruited from 4 urban areas in the United States. Of 3163 participants studied, 2477 were euthyroid, 465 had subclinical hypothyroidism (SCH), 47 overt hypothyroidism (OH), 45 endogenous (endo) subclinical hyperthyroidism (endo-SCT), and 129 had exogenous (exo) SCT due to thyroid hormone supplementation. Participants underwent clinical evaluation, blood sampling and biomarker measurement, 2-dimensional and speckle tracking echocardiography for assessment of left heart myocardial deformation, circulating biomarkers of diastolic overload (NT-proBNP), fibrosis (sST2, gal-3), and cardiomyocyte injury (hs-cTnT).

RESULTS

SCH was associated with higher NT-proBNP (beta = 0.17, P = .004), whereas OH was associated with higher hs-cTnT (beta = 0.29, P = .005). There were also suggestive associations of SCH with higher sST2, as well as endo-SCT with higher gal-3 and lower (worse) left atrial reservoir strain. Left ventricular longitudinal strain and end diastolic strain rate did not differ significantly from euthyroid participants in SCH, OH, or exo-SCT.

CONCLUSION

In this free-living elderly cohort, subclinical and overt hypothyroidism were associated with abnormalities of blood biomarkers consistent with diastolic overload and myocardial necrosis respectively, whereas subclinical hyperthyroidism tended to be associated with myocardial fibrosis and decreased left atrial strain. Our findings could represent stage B heart failure and illuminate distinct aspects of the pathobiology of heart disease related to thyroid gland dysfunction with potential clinical implications.

Investigating Changes in Cardiac Function and Structure of Left Ventricle by Speckle-Tracking Echocardiography in Patients With Hyperthyroidism and Graves' Disease

Subclinical hyperthyroidism is a common thyroid dysfunction that can lead to cardiovascular complications. It is necessary to understand the treatment strategy in clinical practice. This study aimed to investigate the changes in cardiac function and left ventricular (LV) structure by speckle-tracking echocardiography in patients with hyperthyroidism and Graves' disease. PubMed, Medline, Cochrane Library, Embase, and SinoMed were searched for targeted articles, from inception till November 26, 2020, without any language restriction. All studies that evaluated changes in cardiac function and LV structure by speckle-tracking echocardiography in patients with hyperthyroidism and Graves' disease were screened. Included studies met the following inclusion criteria: (1) study population diagnosed with hyperthyroidism or Graves' disease; (2) patients without treatment and are undergoing speckle-tracking echocardiography; (3) necessary data could be extracted from original studies; (4) studies published in English or Chinese; and (5) if the study population was duplicated, only one study from the same institution that provided detailed information or newly published article was selected. All relevant articles from the above databases were screened and assessed according to the inclusion criteria by two reviews independently. Inverse variance methods with random-effects were employed to pool the mean differences (MDs) and the corresponding 95% confidence intervals (CIs). Ten studies with 483 patients and 434 healthy controls were included for data extraction and meta-analysis. On comparing patients with healthy controls, two-dimensional echocardiography revealed significant differences in several parameters including interventricular septal thickness (IVST) [mean difference (MD): 0.43, 95% CI = 0.12–0.73, P < 0.05] and left ventricular end systolic diameter (LVESD) (MD: 1.42, 95% CI = 0.33–2.52, P < 0.05). Moreover, there were significant differences in left ventricular ejection fraction (LVEF) (P < 0.05), global longitudinal strain (P < 0.05), and global circumferential strain (P < 0.05) demonstrated by three-dimensional echocardiography. These findings suggested that left ventricle (LV) function evaluated by speckle-tracking echocardiography showed significant impairment in patients with hyperthyroidism. However, additional original studies and meta-analyses are warranted for an in-depth investigation.

Assessment of Right Atrium Function in Patients With Systemic Lupus Erythematosus With Different Pulmonary Artery Systolic Pressures by 2-Dimensional Speckle-Tracking Echocardiography

OBJECTIVES

To assess right atrium (RA) function of patients with systemic lupus erythematosus (SLE) and pulmonary artery hypertension (PAH) by 2-dimensional speckle-tracking echocardiography.

METHODS

Thirty matched healthy adults were selected as group A. Then, 102 patients with SLE were divided into 3 groups according to the severity of PAH. Group B included 37 patients without PAH (pulmonary artery [PA] systolic pressure ≤ 30 mm Hg); group C included 34 patients with PAH (PA systolic pressure of 30-50 mm Hg); and group D included 31 patients with PAH (PA systolic pressure ≥ 50 mm Hg). Parameters evaluated included RA maximum volume, minimum volume, preatrial contraction volume, passive ejection fraction (EF), and active EF. The global peak longitudinal systolic strain rate and early and late diastolic strain rates of the RA were obtained by 2-dimensional speckle-tracking echocardiography.

RESULTS

No significant differences were found in all parameters between groups B and A (P > .05). The RA maximum volume, minimum volume, preatrial contraction volume, active EF, and late diastolic strain rate in groups C and D were significantly increased compared with those in groups A and B, and the parameters in group D were significantly higher than those in group C (P < .05). Although the RA passive EF, early diastolic strain rate, and systolic strain rate in groups C and D were significantly decreased compared with those in groups A and B, those in group D were significantly lower than those in group C (P < .05).

CONCLUSIONS

Two-dimensional speckle-tracking echocardiography could effectively assess RA function in patients with SLE who have different severities of PAH.

Repercussions of hypo and hyperthyroidism on the heart circadian clock

Myocardial gene expression and metabolism fluctuate over the course of the day in association with changes in energy supply and demand. Time-of-day-dependent oscillations in myocardial processes have been linked to the intrinsic cardiomyocyte circadian clock. Triiodothyronine (T3) is an important modulator of heart metabolism and function. Recently, our group has reported time-of-day-dependent rhythms in cardiac T3 sensitivity, as well as, T3-mediated acute alterations on core clock components. Hypo and hyperthyroidism are the second most prevalent endocrine disease worldwide. Considering the importance of the cardiomyocyte circadian clock and T3 to cardiac physiology, the aim of this study was to investigate the consequences of chronic hypo and hyperthyroidism on 24-h rhythms of circadian clock genes in the heart. Hypo and hyperthyroidism was induced in rats by thyroidectomy (Tx) and i.p. injections of supraphysiological dose of T3, respectively. Here we report alterations in mRNA levels of the major core clock components (Bmal1, Per2, Nr1d1, and Rora) for both experimental conditions (with the exception of Per2 during hyperthyroid condition). Oscillations in mRNA levels of key glucose and fatty-acid metabolism genes known to be clock controlled (Pdk4, Ucp3, Acot1, and Cd36) were equally affected by the experimental conditions, especially during the hypothyroid state. These findings suggest that chronic alterations in thyroid status significantly impacts 24-h rhythms in circadian clock and metabolic genes in the heart. Whether these perturbations contribute toward the pathogenesis of cardiac dysfunction associated with hypo and hyperthyroidism requires further elucidation.