This systematic review and meta-analysis were conducted to evaluate the prevalence of cardiac manifestations associated with multisystem inflammatory syndrome in children worldwide. We conducted electronic searches in Ovid MEDLINE, Ovid EMBASE, and the World Health Organization COVID-19 Literature Database from the inception of the SARS-CoV-2 pandemic to 1 January, 2022. Three authors independently screened the abstracts to determine eligibility, assessed methodology in the full texts, and extracted the data.

We identified 2848 citations; 94 studies (14,932 patients) were included. The prevalence of vasopressors was 48.2% (95% CI 45.1%, 51.3%), left ventricular systolic dysfunction occurred in 37.2% (95% CI 34.1%, 40.3%), myocarditis in 34.1% (95% CI 30.5%, 37.8%), electrocardiographic dysrhythmias and abnormalities detected in 23.1% (95% CI 18.8%, 27.6%), coronary abnormalities identified in 18% (95% CI 16%, 20%), extracorporeal membrane oxygenation deployed in 2.2% (95% CI 1.7%, 2.8%), and mortality rate of 2.2% (95% CI 1.7%, 2.7%). A sensitivity analysis was performed after removing eleven studies with high bias, and the adjusted prevalence was not different than the original evaluation.

In this meta-analysis of the largest cohort of multisystem inflammatory syndrome in children patients to date, we established the most accurate prevalence of the most common cardiac manifestations. Providers will subsequently have more precise data to anticipate patient outcomes and approach discussions concerning the frequency of monitoring outside the acute hospital period.

We herein report on a series of four patients presented to our tertiary care centre with features of multisystem inflammatory syndrome in children and cardiac involvement. Two of our patients had recent exposure to a COVID-19-positive patient, one had recent documented infection, and another had no known positive contact. All the patients were tested positive for severe acute respiratory syndrome coronavirus 2 immunoglobulin G antibody at the time of presentation. All of them fulfilled the diagnostic criteria according to the World Health Organization Centers for Disease Control or the British guidelines for MIS-C (fever for ≥3 days, multisystem involvement (at least two), elevated markers of inflammation, and no other alternative diagnosis).

Cardiac involvement was variable ranging from isolated ectasia of the coronary arteries to full-blown pancarditis such as severe biventricular dysfunction, multi-valvar involvement, and pericardial effusion.

All our patients received intravenous immunoglobulin (2 g/kg), methylprednisolone, and aspirin and some required inotropic support and ICU admission.

Remarkably, all our patients showed significant improvement in their cardiac disease within a few days as evident on serial echocardiographic evaluation. However, we stress the need for long-term follow-up as one of our patients demonstrated mild LV myocardial scarring as evident by gadolinium late enhancement on a cardiac MRI.

Since 1985 a physical and instrumental cardiac study was carried out in 41 children with perinatal HIV-1 infection in order to assess the prevalence and natural history of cardiac involvement. Children were followed for 66 (range 8-109) months; eight of 41 died of HIV-1 related diseases. The cumulative proportion of children with cardiac manifestations at age of seven years was 14.9% (95% CI: 4.9-31.5%). Cardiac abnormalities were detected in eight of 41 patients (19.5%) and were more significantly (p=0.003) recorded in children who died of HIV-1 related diseases (five of eight, 62.5%). Left ventricular systolic function was normal in most patients during the follow-up and did not depend on zidovudine treatment. Two patients had a severe dilated cardiomyopathy and underwent subsequently a stable regression as far as the clinical and instrumental frame was concerned. Only one patient died because of cardiac disease. We conclude that in our group ofperinatally HIV- 1 infected children, cardiac involvement is relatively rare, represents a late complication compared to other related HIV-1 diseases and occurs in advanced stages of illness. Cardiac disease is therefore a hallmark of poor prognosis, but is rarely the ultimate cause of death.