Limitations and strengths
There were limitations and strengths in this study’s design and running, as follows. The most accurate way to evaluate chambers’ volumes and strains is cardiac magnetic resonance imaging (CMR) (21). Although it was better to evaluate the heart condition with CMR, echocardiography is still the most accessible and inexpensive way to carry out the global cardiac status (7). So, in case of having access and enough budgets to perform CMR for research purposes, it would be more reliable to perform this study with CMR, which would probably lead to higher inter-and intra- observer reproducibility. Another noteworthy limitation is the limited sample size. It was a single-center cohort of health care workers, and the COVID-19 pandemic, by its nature of being highly contagious, made it difficult to provide a sample of patients with proper size in different clinical COVID-19 severity groups that may have affected the present results.
Moreover, as the participants were all health care workers and thus aware of alarm signs and symptoms ending to severe COVID-19, they received proper care right away. Consequently, there were fewer patients with cytokine storm and severe COVID-19 pneumonia to measure the impact on the cardiopulmonary system. The bright point of the current study is considering patients without cardiac indication for echocardiography which provides evidence for silent long-term effects of COVID-19 on the cardiovascular system. On the other hand, having a population bare of known cardiac problems excludes the impact of the baseline cardiac complications on the outcomes of the patients. Another novelty of the current study is the duration of the follow-up period (6 months), which is not practiced in any other similar study. It is of note that the participants of this cohort were all young, otherwise healthy, without any history of cardiac disease, and still productive people working as healthcare staff. Hence, the considered response to COVID-19 systemic implications was assessed to be the response of a healthy heart to sepsis. Thus, it can practically be generalizable to the non-complicated heart response to the COVID-19 crisis. The current results may not present the outcomes of aged or, to any extent, previously damaged hearts against the multi-system-involving COVID-19 infection.