We present a case of a 47‐year‐old woman with a history of asthma and mononeuritis who presented with shortness of breath and fatigue. Heart failure was diagnosed and echocardiography revealed large floating thrombi attached to the left ventricular walls. Cardiac magnetic resonance imaging showed evidence of myocarditis and angiitis. Blood count revealed eosinophilia. She was diagnosed with eosinophilic granulomatosis with polyangiitis or Churg–Strauss syndrome (CSS) according to recently updated criteria. Medical management with specific aetiology (anticoagulation or immunosuppression) and heart failure treatment resulted in clinical improvement. We further discuss the diagnostic approach of CSS with cardiovascular complications and therapeutic management.