Directional Coronary Atherectomy as a Diagnostic Adjunct in Suspected IgG4-Related Coronary Artery Disease.

BACKGROUND: Immunoglobulin (Ig) G4-related disease can involve the cardiovascular system, and isolated vessel involvement is diagnostically challenging. CASE SUMMARY: A 79-year-old Japanese man with a history of percutaneous coronary intervention presented with exertional angina. Imaging demonstrated in-stent occlusion of the left anterior descending artery, severe distal left circumflex artery stenosis, and marked adventitial thickening of the coronary arteries and aorta. Serum IgG4 levels were markedly elevated. Directional coronary atherectomy (DCA) enabled retrieval of intimal tissue. Although the pathological findings did not fulfill formal classification criteria, tissue sampling provided supportive histopathological evidence for IgG4-related disease. Prednisolone therapy resulted in regression of adventitial thickening and reduction of nonrevascularized coronary lesions. DISCUSSION: DCA may serve as both a therapeutic strategy and an adjunctive diagnostic approach. TAKE-HOME MESSAGES: DCA may provide supportive histopathological information when conventional biopsy is not feasible, and steroid therapy can be effective for cases of vascular involvement in IgG4-related disease.