Eosinophilic granulomatosis with polyangiitis (EGPA), formerly Churg-Strauss syndrome, is an ANCA-associated small-vessel vasculitis characterized by eosinophilic infiltration, granuloma formation, and necrotizing vasculitis. It progresses through three phases: prodromal (allergic rhinitis, nasal polyps, adult-onset asthma), eosinophilic (peripheral eosinophilia with tissue infiltration of lungs, GI tract, heart), and vasculitic (systemic vasculitis affecting skin, nerves, kidneys, heart). Cardiac involvement (eosinophilic myocarditis, coronary arteritis) is the leading cause of death.