Evaluation of left ventricular myocardial work in patients with hyperthyroidism with different heart rates with noninvasive pressure-strain loop based on two-dimensional speck tracking imaging

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.

Keywords: Hyperthyroidism; left ventricle; myocardial work; pressure-strain loop; tachycardia.

Figure 1

Longitudinal peak strain bull’s-eye diagram and pressure-train loop and myocardial work parameters. (A) A patient with hyperthyroidism and tachycardia: HR =108 bpm, BP =128/81 mmHg, PSD =55.21 ms, GLS =–16%, GWI =1,572 mmHg%, GCW =1,873 mmHg%, GWW =74 mmHg%, GWE =95%. (B) A patient with hyperthyroidism but no tachycardia: HR =86 bpm, BP =125/80 mmHg, PSD =21.19 ms, GLS =–19%, GWI =1,876 mmHg%, GCW =2,043 mmHg%, GWW =74 mmHg%, GWE =96%. (C) Healthy volunteer: HR =66 bpm, BP =111/75 mmHg, PSD =37.94 ms, GLS =–20%, GWI =1,865 mmHg%, GCW =1,948 mmHg%, GWW =46 mmHg%, GWE =97%. HR, heart rate; bpm, beats per minute; BP, blood pressure; PSD, longitudinal peak strain dispersion; GLS, global longitudinal strain; GWI, global work index; GCW, global constructive work; GWW, global waste work; GWE, global work efficiency; GS, global strain; ANT, anterior segment; INF, inferior segment; LAT, lateral segment; POST, posterior segment; SEPT, septal segment; G peak SL Full, global peak strain longitudinal full; AVC, aortic valve closure; HR APLAX, heart rate; LVP, left ventricular pressure.

Figure 2

ROC curve analyses for the accuracy of GWI, GCW, GWW, GWE, GLS, and PSD_N parameters to identify patients with hyperthyroidism with myocardial injury. The analyses include all study participants (N=95). AUC, area under the curve; ROC, receiver operating characteristic; GLS, global longitudinal strain; PSD_N, longitudinal peak strain dispersion normalized by heart rate; GWE, global work efficiency; GCW, global constructive work; GWW, global waste work.

Figure 3

Correlation coefficients plots of parameters. Correlation of all participants between GWE and GLS (A), GCW and GLS (B), GWE and PSD_N (C), GCW and PSD_N (D), GWW and GLS (E), and GWW and PSD_N (F). Correlation between GCW and SBP (G) and between GWW and SBP (H) in group CON. Correlation between GCW and SBP of group TH1 (I) and group TH2 (J). GWE, global work efficiency; GLS, global longitudinal strain; GCW, global constructive work; PSD_N, longitudinal peak strain dispersion normalized by heart rate; GWW, global waste work; SBP, systolic blood pressure.

Figure 4

Bland-Altman plots of the intraobserver agreement for GWI (A), GCW (B), GWW (C), and GWE (D). Bland-Altman plots of the inter-observer agreement for GWI (E), GCW (F), GWW (G), and GWE (H). GWI, global work index; GCW, global constructive work; GWW, global waste work; GWE, global work efficiency; SD, standard deviation.