Assessing left ventricular function in patients with hyperthyroidism across varied heart rates via press-strain loop analysis: a retrospective cross-sectional study.

Background: In the early stages of hyperthyroidism (HTH), cardiovascular symptoms are not prominent, and heart function impairment may occur before structural changes. The non-invasive left ventricular (LV) pressure-strain loop (PSL) allows for early, quantitative assessment of changes in LV systolic function. However, previous studies have not grouped hyperthyroid patients based on the presence or absence of tachycardia. This study aimed to assess the LV function in individuals diagnosed with HTH who exhibit varying heart rates, utilizing the PSL technique.

Methods: Seventy-eight hyperthyroid patients were recruited between December 2022 and September 2023 using a random method and then stratified into two groups based on the presence or absence of tachycardia, designated as HTH1 (tachycardia) group and HTH2 (non-tachycardia) group, respectively. Additionally, a control group comprising 38 healthy volunteers was included for comparison purposes. Standard echocardiographic parameters and LV global longitudinal strain (GLS) were quantified. Furthermore, LV myocardial work parameters, encompassing global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE), were assessed using the PSL technique. The main statistical methods included one-way analysis of variance, LSD-t test, Kruskal-Wallis H test, Bonferroni correction, and χ² test.

Results: Compared to the control group, the systolic blood pressure (SBP), pulse pressure differential, serum free triiodothyronine (FT3) and free thyroxine (FT4) levels of HTH1 and HTH2 subgroups demonstrated elevation, whereas serum thyroid-stimulating hormone (TSH) levels exhibited reduction (P<0.05). Moreover, comparisons between the HTH1 and HTH2 subgroups revealed significantly higher SBP, pulse pressure differential, FT3, and FT4 concentrations in the former relative to the latter (P<0.05). LV ejection fraction (LVEF) exhibited a statistically significant increase in the HTH group compared to the control group (P<0.05). GLS, GWI, and GWE in the HTH group were less compared to the control group, while GWW exhibited an increase in the HTH group relative to the control group (P<0.05). Within the HTH group, both GWI and GWE were significantly lower in the HTH1 subgroup compared to the HTH2 subgroup.

Conclusions: PSL method enables the quantitative assessment of LV myocardial work alterations in individuals with HTH exhibiting varying heart rates, which may help clinical physicians make an accurate early diagnosis and take timely treatment measures.