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.