A forgotten essential chamber that may be involved in the cardiac complications of COVID-19 The right ventricle seems to have been forgotten among heart chambers , although some studies have shown its crucial role in coronavirus disease 2019 (COVID-19) Interestingly, both its size and function are believed to be associated with cardiac complications and mortality in COVID-19 COVID-19 is caused by severe acute respiratory syndrome corona-virus 2 (SARS-CoV-2) which spread globally after the first case was observed in Wuhan at the end of 2019 1 Recent studies suggested that COVID-19 may be accompanied by cardiac complications, including acute coronary syndrome, cardiac arrhythmia, myocarditis, pericardi-tis, and heart failure in nearly 20% of patients, which are ssociated with an increased risk of mortality 2 Laboratory data such as cardiac tropo-nin as well as echocardiography parameters can be effective means of cardiac assessment in these patients Transthoracic echocardiography (TTE) is the optimum method of cardiac imaging used in COVID-19 patients which is able to diagnose different cardiac abnormalities including haemodynamic dysfunction Also, it is useful for the prediction of future cardiac morbidity in these patients 3 Reduced right ventricular (RV) activity is a good predictor for heart failure and cardiac mortality 4 The effect of COVID-19 on the right ventricle activity is in the main unknown It seems that the pathophysiological pathways of COVID-19 including increased after-load after acute respiratory distress syndrome, pulmonary embolism, cytokine-negative inotropic effects, and renin-angiotensin system dys-function are possible mechanisms for RV dysfunction in COVID-19 patients 5 A summary of some studies which have been conducted to assess RV function in COVID-19 patients is presented in Table 1 Li et al performed an echocardiographic investigation in 120 cases of COVID-19 They assessed RV fractional area change, tricuspid annu-lar plane systolic excursion, and Doppler tricuspid tissue annular velocity In their study, RV function was categorized by right ventricular longitudinal strain (RVLS) It was concluded that patients with the lowest RVLS tertile were more susceptible to cardiac injury, and a higher mortality rate was observed in this group In addition, patients' mortality was associated with RVLS, RV fractional area change, and tricuspid annular plane systolic excursion 6 In the study of Szekely et al , the most common cardiac pathology in COVID-19 was RV dilatation (39%) which was more than both left ventricular (LV) diastolic dysfunction (16%) and LV systolic dysfunction (10%) In fact, it was concluded that LV systolic function is preserved in these patients, although LV diastolic function and RV function are impaired 2 In a retrospective study by Argulian et al , echocardiography parameters of 105 cases of COVID-19 were studied RV dilation was observed in 32 patients (31%) Furthermore, RV hypokinesis and moderate to severe tricuspid regurgitation were more common in patients with RV dilation Interestingly, there were no differences in LV size and function in patients with RV dilation in comparison with normal patients 7
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