Cardiac involvement in children with paediatric multisystem inflammatory syndrome temporally associated with SARS-CoV-2 (PIMS-TS): data from a prospective nationwide surveillance study

BACKGROUND: Paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS) may occur 4 to 8 weeks after SARS-CoV-2 infection. The acute presentation of PIMS-TS has been well described, but data on longer-term outcomes, particularly cardiac, is scarce. METHODS: This prospective nationwide surveillance study included children and adolescents less than 18 years of age who were hospitalised with PIMS-TS in Switzerland between March 2020 and March 2022. Data was collected from all 29 paediatric hospitals through the Swiss Paediatric Surveillance Unit (SPSU) during hospitalisation and approximately six weeks after discharge. The data was analysed after categorising the participants into three groups based on their admission status to the intensive care unit (ICU) (non-ICU, ICU-moderate) and the requirement for invasive ventilatory and/or inotropic support (ICU-severe). RESULTS: Overall, 204 children were included of whom 194 (95.1%) had follow-up data recorded. Median age was 9.0 years (interquartile range [IQR] 6.0-11.5) and 142 (69.6%) were male. In total, 105/204 (51.5%) required ICU admission, of whom 55/105 (52.4%) received inotropic support and 14/105 (13.3%) mechanical ventilation (ICU-severe group). Echocardiography was performed in 201/ 204 (98.5%) children; 132 (64.7%) had a cardiac abnormality including left ventricular systolic dysfunction (73 [36.3%]), a coronary artery abnormality (45 [22.4%]), pericardial effusion (50 [24.9%]) and mitral valve regurgitation (60 [29.9%]). Left ventricular systolic dysfunction was present at admission in 62/201 (30.8%) children and appeared during hospitalisation in 11 (5.5%) children. A coronary artery abnormality was detected at admission in 29/ 201 (14.2%) children and developed during hospitalisation or at follow-up in 13 (6.5%) and 3 (1.5%) children, respectively. None of the children had left ventricular systolic dysfunction at follow-up, but a coronary abnormality and pericardial effusion were found in 12 (6.6%) and 3 (1.7%) children, respectively. School absenteeism at the time of follow-up was more frequent in children who had been admitted to the ICU (2.5% in the non-ICU group compared to 10.4% and 17.6% in the ICU-moderate and ICU-severe group, respectively) (p = 0.011). CONCLUSION: Cardiac complications in children presenting with PIMS-TS are common and may worsen during the hospitalisation. Irrespective of initial severity, resolution of left ventricular systolic dysfunction is observed, often occurring rapidly during the hospitalisation. Most of the coronary artery abnormalities regress; however, some are still present at follow-up, emphasising the need for prolonged cardiac evaluation after PIMS-TS.