Detailed Assessment of Left Ventricular Function in Multisystem Inflammatory Syndrome in Children Using Strain Analysis.

Background: Cardiac manifestations in multisystem inflammatory syndrome in children (MIS-C) occur in ∼80% of patients. Left ventricular (LV) systolic dysfunction is the most frequent cardiac finding. Methods: In this single-center, retrospective cohort study we report on detailed assessment of LV function in MIS-C patients using strain and strain rate analysis. We compare those with normal peak systolic strain z-scores (both longitudinal and circumferential strain) to those with abnormal peak systolic strain z-scores (decreased circumferential and/or longitudinal strain). Results: Among 25 patients, 14 (56%) were male, 20 (80%) were Black or Hispanic, 13 (52%) were overweight/obese, and median age was 11.4 years (IQR, 7.5 to 16). Median ejection fraction (EF) was 55.2% (IQR, 48.3 to 58%) with the abnormal strain patients having lower EF (p<0.01). Demographics were similar between groups. The abnormal strain patients had more organ systems involved and were more likely to require inotropic support. When comparing MIS-C patients with normal EF (n=15) to controls, MIS-C patients had lower peak systolic strain as well as lower early diastolic strain rates. In patients with initially depressed function, EF normalized in 8/10 (80%) but 4/11 (36%) patients had persistently abnormal systolic strain after discharge. Conclusion: Left ventricular systolic dysfunction is common in the acute phase of MIS-C and detection may be improved with strain imaging. Longitudinal cardiac follow-up is imperative as some patients may be at risk for persistent LV dysfunction.