Churg-Strauss syndrome (CSS) is a rare small-vessel vasculitis typically associated with adult-onset asthma, peripheral and tissue hypereosinophilia, migratory pulmonary infiltrates, upper respiratory tract symptoms, and clinical evidence of systemic vasculitis. Cardiac involvement is a well-recognized complication with an estimated prevalence of 60%. Heart disease is associated with poor prognosis, accounting for almost 50% mortality in CSS. We present a case of a 48-year-old woman with CSS complicated by congestive heart failure with left ventricular ejection fraction of 25%, who was initially treated with long course of high-dose steroids without any clinical or echocardiographic improvement. She was referred to our hospital 1 year later and was initiated with cyclophosphamide 2 mg/kg per day and prednisone 60 mg/d followed by slow taper. Subsequently, the patient had remarkable improvement. Patient was then transitioned to azathioprine for 1.5 years with sustained disease remission. It may be difficult to determine myocardial disease activity status versus tissue damage in CSS with prolonged duration of heart failure symptoms. This is the first case report demonstrating that CSS cardiac disease may remain active despite 1 year of corticosteroid therapy, and significant improvement or remission can still be achieved by administering more aggressive cytotoxic immunosuppressive therapy.