Discussion
TTE is the main imaging technique to investigate LV structure and
functions, but conventional echocardiographic techniques may not be
enough to show the pre-clinic mechanical deterioration. 2D-STE is a
better method for evaluating regional and global myocardial deformation
and can diagnose subclinical myocardial dysfunction earlier and may
detect patients who needs further investigations, cardiac controls, and
myocardial protection (11-14).
In our study we evaluated the difference of left ventricular myocardial
functions with LV-GLS between asymptomatic and symptomatic patients who
had mild COVID infection. Życzkowska et al also investigated mild COVID
infection’s effects in heart functions including standard and advanced
echocardiographic techniques but the result of the study did not show
significant impairment in left ventricle functions (20).
The real prevalence of the cardiac involvement is not clear, and the
study results are conflicting. It can be speculated that these results
may be related with the study populations. In a study from a single
tertiary centre, Erdol et al evaluated 100 consecutive COVID-19 proven
patients after quarantine period with CMR and cardiac involvement was
detected in 49 patients in which 41 patients described cardiac symptoms
that were not present before COVID infection, and the results were
statistically significant (p=0,001). In 24 patients out of 51 who does
not have cardiac involvement in CMR were asymptomatic and this result
was also statistically significant (p=0,001) (21).
As it’s known that the 2D-STE and CMR results are compatible with each
other, 2D-STE for LV quantification has been validated against MRI (22).
Puntmann at al. evaluated left ventricle with CMR after mild COVID
infection without known cardiac disease and showed more diffuse
myocardial edema at follow-up in patients with ongoing symptoms as
compared to the ones who has improved. They also investigated the LV-GLS
values between the control and post-COVID patients and even though the
average values of LV-GLS were in normal ranges in both groups, the
difference was statistically different (23). In our study, even the
average LV-GLS value was lower in the symptomatic group, the difference
was not statistically different.
In another hybrid study using both TTE, 2D-STE and CMR, Brito et al.
evaluated young athletes who had mild to moderate degree COVID-19
infection. Even no athlete showed ongoing myocarditis imaging features,
the result of this study shows that mild or asymptomatic COVID-19 is not
a benign illness, as more than one-half of the younger individuals
showed subclinical myocardial and pericardial disease (24). The
reduction of LV-GLS values is seemed to be obtained mostly in
symptomatic patients or in patients who have an additional finding as
pericardial involvement, and it is independent of the COVID-19 disease
severity.
The limitations of our study are, it’s a single centre retrospective
study and the GLS values of our study population are not known before
the COVID infection, and the number of the study population is low
because we have stopped including patients after August 2021, the date
that the m-RNA vaccines are applied to the general population in Turkey
to avoid the effects of m-RNA vaccine’s myocardial damage and
myocarditis side effect.
Conclusion
Despite the small number of the patients in the study group, the results
of this study show that more symptomatic patients than the asymptomatic
ones have impaired LV-GLS values. Even if it is not statistically
significant, the mean LV-GLS values are also reduced in symptomatic
patients after mild COVID-19 infection. It can be concluded that close
follow-up of these patients in the future may be beneficial until
randomized controlled studies with high numbers of patients are
conducted.