AbstractObjectiveChurg‐Strauss syndrome (CSS) is a rare form of systemic vasculitis. Previous studies showing cardiac involvement in CSS patients were limited in the number of patients and were often based solely on clinical manifestations. The aim of the present study was to determine in detail the incidence of cardiac involvement in a large population of ambulatory CSS patients.MethodsThirty‐two consecutive patients with CSS in remission (mean ± SD duration of disease between diagnosis and enrollment 6.1 ± 5.8 years, mean ± SD age 61 ± 10 years) who were previously unaware of cardiac involvement were compared with 32 randomly selected age‐ and sex‐matched control subjects, using clinical evaluation, electrocardiography (EKG), echocardiography, and cardiac magnetic resonance imaging (MRI).ResultsDetailed cardiac evaluation revealed a 62% prevalence of cardiac involvement in CSS patients compared with 3% in controls (P < 0.001), with clinical symptoms in 26% and 3%, respectively (P = 0.009), EKG abnormalities in 66% and 3%, respectively (P < 0.001), and echocardiographic defects in 50% and 3%, respectively (P < 0.001). Cardiac MRI detected cardiac manifestations in 62% of CSS patients. In the presence of cardiac MRI abnormalities, echocardiography could detect cardiac involvement with a sensitivity of 83% and a specificity of 80%. The absence of symptoms or EKG abnormalities did not exclude cardiac involvement, because abnormalities could still be detected in 38% of these patients at the time of echocardiography or cardiac MRI.ConclusionThese results demonstrate a high incidence of cardiac involvement in CSS patients. Systematic cardiac evaluation including detailed imaging is required to properly identify CSS patients with cardiac involvement.