Serial inflammation imaging with pericoronary adipose tissue in patients with immunoglobulin G4-related coronary periarteritis: a case report.

Background: Immunoglobulin G4-related disease (IgG4-RD) is a systemic immune-mediated inflammatory disease that infrequently involves the coronary arteries. Given that pericoronary adipose tissue (PCAT) attenuation reflects the degree of inflammation in the coronary arteries, monitoring inflammation with PCAT may enable evaluation of disease activity in IgG4-related coronary periarteritis (CP).

Case Summary: A 58-year-old man with a history of IgG4-RD presented with ST-segment elevation myocardial infarction. Emergent coronary angiography revealed a severe stenotic lesion in the mid-segment of his left circumflex artery (LCX). Intravascular ultrasound (IVUS) imaging demonstrated thickening of the adventitia, and optical coherence tomography (OCT) showed the formation of vasa vasorum in the proximal segment of the LCX. Along with an elevated IgG4 level (1890 mg/dL), he was diagnosed with IgG4-related CP. Coronary computed tomography angiography (CCTA) after percutaneous coronary intervention (PCI) revealed soft tissue proliferation with elevated PCAT attenuation [PCAT attenuation = -68.4 Hounsfield units (HU)] around the proximal LCX. Following the initiation of prednisolone, the IgG4 level decreased to 239 mg/dL at 8 months post-PCI. Follow-up IVUS showed reduced adventitial thickness, and most of the previously observed vasa vasorum had disappeared on OCT. Furthermore, CCTA demonstrated a reduction in PCAT attenuation (to -81.8 HU), accompanied by a reduction in soft tissue volume.

Discussion: In this case, serial PCAT analysis demonstrated resolution of inflammatory activity in response to prednisolone therapy. Serial PCAT imaging may have potential for evaluating disease activity and monitoring response to anti-inflammatory therapy in patients with IgG4-RD.