Abstract
BACKGROUND: We investigated the application value of no-invasive myocardial work in evaluating left ventricular (LV) function in patients with hyperthyroidism. METHODS: Sixty-five patients with an initial hyperthyroidism diagnosis were sorted into tachycardia (group TH1, n=31) and without tachycardia (group TH2, n=34) groups. Thirty healthy participants served as the control group (group CON). LV strain parameters and LV myocardial work parameters were evaluated at rest. Each parameter's value in identifying myocardial damage was analyzed using receiver operating characteristic curves. The correlation of myocardial work parameters with global longitudinal strain (GLS), longitudinal peak strain dispersion (normalized by heart rate, PSD(N)), and systolic blood pressure (SBP) was analyzed. RESULTS: There was no difference in classic echocardiographic parameters between the groups. Compared with that in group CON, GLS decreased in groups TH1 and TH2 (TH1 17.99%±2.21% and TH2: 19.00%±2.85% vs. 20.27%±1.49%; both P<0.05); there was no significant difference between groups TH1 and TH2. PSD(N) increased in groups TH1 and TH2 (TH1 73.13±19.51 ms and TH2 55.06±17.03 vs. 44.13±8.65 ms; both P<0.05); it was higher in group TH1 than in group TH2 (P<0.05). Myocardial global work efficiency (GWE) decreased in groups TH1 and TH2 {TH1 95% [interquartile range (IQR), 94-95%] and TH2 96% (IQR, 95-97%) vs. 97% (IQR, 96-97%); both P<0.05}; it was lower in group TH1 than in group TH2 (P<0.05). Global constructive work (GCW) decreased in group TH1 (1,865.29±284.13 vs. 2,030.33±252.52 mmHg%; P<0.05), but was not different from that in group TH2; there was no difference between groups TH2 and CON. Global wasted work (GWW) increased in groups TH1 and TH2 [TH1 83.00 (IQR, 74.00-97.00) mmHg% and TH2 69.50 (IQR, 51.25-84.25) vs. 50.50 (IQR, 40.75-65.25) mmHg%; both P<0.05]; it was higher in group TH1 than in group TH2 (P<0.05). The area under the GWE curve was the largest (area under the curve =0.835), and the optimal cutoff point was 96.5%, with a sensitivity of 0.83 and a specificity of 0.70. GWE and GCW were positively correlated with GLS and negatively correlated with PSD(N). GWW was negatively correlated with GLS and positively correlated with PSD(N). In group CON, GCW and GWW were positively correlated with SBP; GWE was not correlated with SBP. In groups TH1 and TH2, GCW was positively correlated with SBP, but not with GWW or GWE. CONCLUSIONS: Hyperthyroidism can significantly decrease the GWE and increase GWW of the left ventricle. This change is more pronounced in patients with tachycardia. Myocardial work could be a novel method for the evaluation of LV myocardial function in patients with hyperthyroidism.