Fulminant Influenza B Myocarditis in an Adolescent Requiring Venoarterial Extracorporeal Membrane Oxygenation (VA-ECMO): Complete Recovery at a Pediatric Cardiac Referral Center in Mexico

Influenza is a common viral infection associated with seasonal outbreaks; however, fulminant myocarditis secondary to influenza Type B represents a rare and life-threatening complication in the pediatric population, with poorly understood pathophysiology. Only a limited number of cases have been reported worldwide, and to our knowledge, this is the first published case in Mexico. We report the case of a previously healthy 13-year-old girl who presented with a five-day history of nonspecific symptoms and rapidly progressed to cardiogenic shock. Prompt recognition and a multidisciplinary approach were essential, involving the pediatric cardiology, cardiac surgery, intensive care, and cardiac imaging teams. Advanced mechanical circulatory support was initiated, including an intra-aortic balloon pump and extracorporeal membrane oxygenation. Medical management included antiviral therapy, corticosteroids, and intravenous immunoglobulin. Following 45 days of intensive management, the patient demonstrated complete recovery of cardiac function and was discharged with close outpatient follow-up. This case highlights the importance of early recognition of fulminant myocarditis in pediatric patients with influenza infection and demonstrates that timely multidisciplinary management and advanced mechanical circulatory support can result in favorable outcomes, even in severe presentations.