Long-term evolution of myocardial strain and coronary artery Z-scores in multisystem inflammatory syndrome in children versus Kawasaki disease

Multisystem inflammatory syndrome in children (MIS-C) and Kawasaki disease (KD) are pediatric inflammatory conditions which share overlapping clinical features, yet their long-term cardiovascular trajectories remain incompletely characterized. Understanding differences in myocardial strain evolution and coronary artery Z-score progression is essential for optimizing surveillance strategies and risk stratification. Aims of this review were to comprehensively compare the long-term evolution of myocardial strain parameters and coronary artery Z-scores in children with MIS-C versus KD through mid- and long-term follow-up assessment studies, and to identify clinical implications for monitoring and management. A comprehensive literature search was conducted in PubMed to identify studies evaluating myocardial strain and coronary artery Z-scores in MIS-C and KD. Publications from January 2020 to February 2026 were considered for MIS-C, with earlier key studies on KD included to contextualize established cardiac outcomes. Observational studies and cohort reports describing echocardiographic findings and follow-up data were reviewed. Available evidence indicates that MIS-C commonly presents with acute myocardial dysfunction, frequently characterized by reduced global longitudinal strain despite preserved or mildly reduced ejection fraction; in most cases, myocardial strain abnormalities substantially improve within weeks to a few months following treatment. In contrast, myocardial strain impairment in KD, which typically presents at less than 5 years of age, is less pronounced; coronary artery involvement shows an opposite trend, as KD is more frequently associated with coronary dilations and aneurysm formation, reflected by persistent elevations in coronary artery Z-scores, whereas coronary abnormalities in MIS-C are milder and often transient. Recovery patterns therefore differ, with MIS-C demonstrating rapid myocardial functional recovery, and KD carrying a greater risk of long-term coronary artery sequelae. MIS-C and KD exhibit distinct cardiovascular phenotypes: MIS-C is primarily characterized by reversible myocardial dysfunction, whereas KD remains a condition most strongly associated with a risk of persistent coronary artery abnormalities. Deciphering these differences may help guide disease-specific cardiac monitoring and long-term follow-up strategies in affected children.