This study has involved patients who were hospitalized with COVID-19 in a University Hospital in North-East Italy and had been consecutively recruited, after hospital discharge, in a short-term follow-up. In these patients, cardiac structure and function that were assessed by two-dimensional, Doppler, and TDI echocardiography did not differ from controls who were matched for age, sex, body mass index, blood pressure, and major coexisting conditions. Moreover, structural and functional characteristics of the heart were comparable in patients who had recovered from mild-to-moderate or severe COVID-19. Despite the descriptive nature of this study due to its observational design, these echocardiographic findings together with normality of serum troponin, strongly suggest that patients who recover from COVID-19 do not have considerable pathological sequelae in the heart.
There is now considerable interest in the identification of persistent organ damage in survivors of COVID-19. This topic has ended up in the spotlight after demonstration of a pathological involvement of many organs different from the lung during the acute phase of infection [3]. Cardiac injury has been identified by detection of increased markers of myocardial damage during the critical stage of COVID-19 [17] and has been associated with an increased risk of death [6, 7]. Anecdotal necropsy studies conducted in subjects who died with COVID-19 have identified myocardial infiltration by interstitial mononuclear inflammatory cells, suggesting existence of a SARS-CoV-2-related myocarditis [18, 19]. Also, isolated cases of severe myocarditis with biventricular dysfunction have been reported in patients with COVID-19 [20, 21], even in the absence of overt pulmonary disease [22]. Although position statements of scientific societies have suggested use of targeted echocardiography for cardiac screening of patients with COVID-19 [13, 23], information obtained in the acute phase of illness is limited to a few studies. Right ventricular dilatation and reduced right ventricular fractional area change were observed in 27% of 74 patients with COVID-19 pneumonia and increased troponin levels, suggesting right ventricular systolic dysfunction as a possible consequence of acute pulmonary arterial hypertension [24]. Signs of pulmonary hypertension were observed with use of cardiac ultrasound in another investigation of 112 COVID-19 patients [25]. In a more recent systematic echocardiographic study conducted within 24 h of hospital admission in 100 COVID-19 patients, right ventricular dilatation and dysfunction have been reported in 39% of patients, left ventricular diastolic dysfunction in 16%, and left ventricular systolic dysfunction in 10% [26]. Thus, evidence obtained in the acute phase of COVID-19 has consistently and prevalently indicated a functional involvement of the right ventricle in a substantial proportion of patients. In this context, right ventricular dysfunction could be due to a hemodynamic overload caused by an increased pulmonary arterial pressure that, in turn, results from pulmonary thromboembolism.
Pulmonary thromboembolism has been demonstrated in patients who died with COVID-19 pneumonia as a possible consequence of a COVID-19 induced prothrombotic state [27]. The presence of a prothrombotic state in COVID-19 patients has also been supported by frequent detection of markedly increased D-dimer levels [28], and therefore, specific attention should be directed to assessment of right ventricular function even after recovery from infection. In this study, both right ventricular function and systolic pulmonary arterial pressure did not differ in patients who recovered from COVID-19 and controls. Also and most important, no significant abnormalities in right ventricular function and systolic pulmonary arterial pressure were found despite detection of persistent pulmonary involvement in COVID-19 patients who had been hospitalized with severe illness. These observations strongly suggest that cardiac changes that are associated with pulmonary involvement of COVID-19 during the acute phase of infection are rapidly reversed after recovery from disease.
More recently, two cross-sectional magnetic resonance studies have examined the heart of COVID-19 survivors in the early recovery phase. Puntmann et al. reported on 100 COVID patients who recovered from infection and had a cardiac magnetic resonance scan a mean of 71 days after diagnosis [29]. These subjects had larger left ventricular volumes and lower ejection fraction compared to controls, and 60% had evidence of ongoing myocardial inflammation. Another study by Rajpal et al. reported on 26 young athletes who recovered from COVID-19 and had a cardiac magnetic resonance from 11 to 53 days after diagnosis [30]. Of these patients, four had imaging data suggestive of myocarditis and eight of possible prior myocardial injury. Both these studies reported changes of the left ventricle, whereas, as indicated above, most magnetic resonance data obtained during the acute phase of COVID-19 reported involvement of the right ventricle. To notice, more than two-thirds of patients included in Puntmann’s paper were not hospitalized during the acute phase of COVID-19 and patients included in Rajpal’ s study were asymptomatic or mildly symptomatic, which suggests that their clinical conditions at presentation were not severe. This observation raises an important question on what could be the meaning, in terms of clinical relevance, of cardiac changes that were detected by magnetic resonance imaging in these patients. It would be definitely difficult to reconcile all these findings, because cardiac changes in people who recover from COVID-19 appear to be highly variable and this might depend on the technique that is used, the characteristics of patients in terms of severity of disease, and timing of examination. In particular, cardiac findings might differ significantly from the acute phase of infection and the short-term and long-term recovery phase and this is why it will be important to monitor the cardiac conditions of COVID-19 survivors even in a long-term follow-up.
Because cardiac abnormalities may persist in COVID-19 patients after viral clearance is achieved, or even arise in the chronic phase of disease, evaluation of cardiac structure and function in patients who recover from clinically relevant illness is of great importance. The present study was conducted during the pandemic peak in a geographic area of northeast Italy that has faced a slightly lower burden of infectivity, morbidity, and mortality than other regions in this country. However, during the study period mortality among COVID-19 patients who were admitted to our hospital with severe illness was 55%. Notably, the characteristics of patients included in our analysis overlap those that have been reported in much larger case series of patients with COVID-19 [31]. Consistent with previous descriptions of disease, our patients with severe COVID-19 were more frequently males, had lower lymphocyte count, and higher serum values of C-reactive protein, lactate dehydrogenase, procalcitonin, D-dimer, and interleukin 6 than patients with mild-to-moderate COVID-19 [2]. Therefore, despite the important limitation due to the small size of our study, these findings could be reasonably generalized to all subjects that recover from COVID-19.
Additional limitations of our study should be highlighted. First, lack of echocardiographic measurements obtained during the hospital stay in the acute phase of COVID-19 does not allow any longitudinal assessment of cardiac changes. Second, inclusion of consecutive COVID-19 patients who attended the follow-up visits might have led to a selection bias that occurs almost inevitably in observational studies. Third, although the matching process of control subjects was accurate for demographic and clinical variables, uncontrolled confounders might have affected the final results. For instance, significant differences in the frequency of use of antivirals and interleukin-6 antagonists between patients with mild-to-moderate and severe COVID-19 could have affected the cardiac outcome. Last, because data were collected after a median of 6 weeks after COVID-19 diagnosis, these do not provide information on the cardiac outcome of infection in a longer time span.
In conclusion, in this study we did not identify structural or functional abnormalities in the heart of survivors of COVID-19 more than a month after the first detection of infection. No abnormalities were also observed in the heart of patients who recovered from severe COVID-19. These findings suggest that patients who recover from COVID-19 do not have considerable cardiac sequelae, but this evidence needs to be further investigated in larger and longer-term studies.