Acute myocardial injury has been demonstrated in 7.2%-12% of patients with COVID-19 in preliminary reports, with a higher prevalence among those requiring intensive care 10. Mortality data from 44672 cases of COVID-19 released by the Chinese Centre for Disease Control and Prevention demonstrate that patients with cardiovascular comorbidities show a much higher mortality11.
But there still lack a systematic and comprehensive study including mild and severe patients in the assessment of left ventricular, left atrial and right ventricular function.
The aim of the present study was to evaluate the cardiac function by standard and strain echocardiography including mild and severe patients with COVID-19. We observed that: 1. Both mild and severe COVID-19 infected patients showed reduced left ventricular diastolic function compared with control group; 2. Severe patients with COVID-19 exhibited exacerbated right ventricular systolic function; 3. Both mild and severe patients with COVID-19 showed impaired left ventricular strain, and the strain in severe patients even worse, suggesting all the patients may had early systolic function. 4. The strain in apical segment of mild patients with COVID-19 was elevated compared with basal and middle segment. 5.There was a negative correlation between LV GLS and log TnT-hs, as well as NT-pro BNP. 6. The EF value and strain of left atrium of mild and severe patients with COVID-19 decreased; 7.LV GLS, LV GCS and LA GLS might predict the severity of COVID-19. 8. In the follow-up of severe COVID-19 infected patients, their cardiac structure and function had no change, while left atrial and ventricular strain exhibited an increased trend.
In the present study, there was no difference in the size of LV and LVEF, among the 3 groups. IVS and LVPW in severe patients with COVID-19 were thicker than mild patients and the controls. There were 8 severe patients with hypertension. However, only one mild patient with hypertension. That might contribute to thicker IVS and LVPW12. In addition, the age may also have an effect on this cardiac performance13. In our investigation, E/e’ in severe patients with COVID-19 were higher than mild and control groups, probably suggesting elevated LV filling pressure. Furthermore, no difference in RV among the 3 groups. TDI-s and TAPSE, the index of right ventricular systolic function, in severe patients were lower than that in the other two groups, suggesting right ventricular systolic dysfunction, which was seen, particularly in the context of severe parenchymal lung disease and acute respiratory disease13. Previous study also demonstrated that compared with survivors, nonsurvivors displayed enlarged right heart chambers, diminished RV function, and elevated pulmonary artery systolic pressure.14 7 of 17 (42%) needed prone positioning for severe Hypoxia had RV dysfunction(RV FAC < 35%). 15
LA is considered to modulate left ventricular filling and cardiovascular performance as (i) a reservoir for pulmonary venous return during ventricular systole,(ii) a conduit for pulmonary venous return during early ventricular diastole, and (iii) a booster pump that augments ventricular filling during late ventricular diastole.16 LA size is strong predictor of cardiovascular morbidity and death17.LA size correlates with both LA and left ventricular(LV) function. Previous study found no difference in LA dimension between survivors and nonsurvivors with COVID-1914, and there is still lack of study on left atrial strain for now. In our study, higher LA volume and lower LAEF were observed in severe and mild patients with COVID-19 than control group. Further, LA myocardial deformation is assessed as global longitudinal strain. 18In addition, the results showed that LAGLS decreased in severe and mild patients, suggesting the LA systolic dysfunction. All LA volume, LAEF and LAGLS showed LA systolic dysfunction, contributing to LV dysfunction.
Strain image is superior to standard echocardiography for myocardial injury detection in patients and reflects the complex deformation pattern of the heart during systole19. Previous study showed that LV GLS measurement are stable and repeatable, which have additional predictive value for evaluating the rest cardiac function of patients.20 The normal LV GLS measured by Qlab is 18.9 ± 2.5%21. Though there was no significant change in LVEF and LV volumes, significantly lower LV GLS and LV GCS were observed in severe and mild patients with COVID-19 compared with control group, especially in severe group. Although in severe patients, 2 patients with coronary heart disease and 1 with chronic heart disease may contribute to worse GLS. Patients with hypertension may also lead to lower GLS22. This result showed subclinical cardiac systolic dysfunction in patients with COVID-19. Troponin and NT-pro BNP is a widely accepted biomarker of myocardial injury, and elevated serum levels have been a notable feature during recent epidemics of respiratory virus infections.20Accordingly, we observed the troponin and NT-pro BNP were negatively correlated with LV GLS in severe patients. Previous data indicated a decreased myocardial longitudinal strain in fulminat myocarditis especially decreased in the basal and middle segments4,23,which was similar to our results, our results observed the apical LS in mild patients was higher than middle and basal segment, however, no significant difference among basal, middle and apical LS,CS in severe patients, as shown in Table 4. Previous study showed that GLS can predict functional capacity in patients with preserved LVEF heart failure and to assess prognosis in reduced LVEF heart failure24. And it could classify HF patients according to the functional capacity.25 In this study, we found that GLS had a low predicted value of the disease severity, which may stratify the patients with unknown condition and therefore to deserve more differentiated treatment.
In our study, only 13 severe patients in ICU received echocardiography one more time. Compared with the first examination, no change in cardiac structure on follow-up. For the strain, our results showed only LV GCS increased (30.40 ± 7.51 vs 23.05 ± 8.56, P < 0.05) in severe patients when compared with the first echocardiography, while the LV GLS and LA GLS exhibited an increased trend. Furthermore, the line chart based on 10 patients for 16 days also showed steadily rising trend. Alleviating myocardial injury was implied, although which needed longer observation. Previous study showed cardiac impairment caused by SARS-CoV in the more critically ill patients may be reversible on recovery26.