Eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome) masquerading as acute ST-elevation myocardial infarction with complete resolution after immunosuppressive therapy: a case report

BACKGROUND: Eosinophilic granulomatosis with polyangiitis (EGPA, formerly known as Churg–Strauss syndrome) is a rare autoimmune condition characterized by inflammation of small- and medium-sized blood vessels, which usually presents with systemic vasculitis preceded by airway allergic hypersensitivity. CASE SUMMARY: Here, we report a highly unusual case of acute ST-elevation myocardial infarction in a young and fit man with no cardiovascular risk factors. His emergency coronary angiography revealed disproportionately severe widespread coronary artery disease. We describe the diagnostic challenges with emphasis on meticulous history-taking (deep hyponasal voice, anosmia, and childhood asthma), supported by timely blood markers (peripheral eosinophilia and raised CRP), and multi-modal imaging (severe paranasal sinusitis on cranial magnetic resonance imaging and multiple lung infiltrates with small patches of ground-glass appearance on thoracic computed tomography), to reach a diagnosis of EGPA coronary vasculitis with particular reference to the American College of Rheumatology EGPA classification. Importantly, with prompt immunosuppression, his coronary lesions resolved completely without the need of any surgical or percutaneous revascularisation. He remained well and asymptomatic on maintenance immunosuppressants at 1 year follow-up. DISCUSSION: This case highlighted the rare but recognized involvement of the coronary arteries in systemic EGPA vasculitis, which can sometimes mimic atherosclerotic coronary disease and acute coronary syndrome.