Cardiovascular Involvement and Its Association with Disease Severity and Recovery in SARS-CoV-2 Associated Multisystem Inflammatory Syndrome in Children

Background: Multisystem inflammatory syndrome in children (MIS-C) is a severe clinical entity emerging after severe acute respiratory syndrome coronavirus 2 infection, often characterized by cardiovascular involvement. This study aimed to evaluate the frequency and spectrum of cardiovascular involvement in children with MIS-C and to assess its association with clinical severity, biomarker profiles, and recovery outcomes. Methods: This study included 54 children diagnosed with MIS-C between June 2020 and December 2023. Clinical features, laboratory parameters, electrocardiographic and echocardiographic findings, treatments, and outcomes were analyzed. Clinical severity was classified as mild, moderate, or severe. Kaplan–Meier and Cox regression analyses were used to evaluate recovery trajectories and identify independent predictors. Results: Cardiovascular involvement was detected in 37% of patients. The most common findings were mitral regurgitation (50%), left ventricular dysfunction (20.4%), and pericardial effusion (18.5%). Patients with cardiovascular involvement were older and more likely to present with dyspnea, chest pain, tachycardia, tachypnea, and hypotension (all p < 0.01). They exhibited significantly higher C-reactive protein (CRP), interleukin-6 (IL-6), B-type natriuretic peptide (BNP), urea, and creatinine levels, and lower lymphocyte counts ( p < 0.05). Moderate-to-severe cases showed markedly higher rates of left ventricular dysfunction (44%), mitral regurgitation (100%), pericardial effusion (36%), arrhythmias (16%), hypotension (44%), and inotropic requirement (44%) compared with mild cases (all p < 0.01). Recovery was significantly delayed in patients with cardiovascular involvement (median 12.5 vs. 8.0 days; p = 0.008) and in moderate-to-severe cases (14.0 vs. 7.5 days; p < 0.01). In Cox regression analysis, independent predictors of delayed recovery included cardiovascular involvement (HR: 0.48), CRP > 200 mg/L (HR: 0.52), lymphocyte count < 1000/µL (HR: 0.41), BNP > 10,000 ng/L (HR: 0.35), and IL-6 > 100 pg/mL (HR: 0.44). Conclusion: Cardiovascular involvement in MIS-C is a strong marker of severe disease, heightened systemic inflammation, and prolonged recovery. Echocardiographic abnormalities, combined with elevations in CRP, IL-6, and BNP provide valuable prognostic information.