Background/Purpose: IgG4-related disease (IgG4-RD) classically presents with a mass or diffusely enlarged organ, but it also affects blood vessels of all sizes. Coronary artery involvement (CAI) is well described but understudied. Prior work demonstrated CAI in 13 out of 361 (4%) IgG4-RD patients, however it was limited by lack of standardized screening for the evaluation of CAI1. The goal of our study was to establish a conservative estimate of the true prevalence of CAI by screening IgG4-RD patients that had prior cross-sectional imaging of the chest, regardless of whether CAI was clinically suspected.

Methods: IgG4-RD patients were identified using the STAnford medicine Research data Repository by searching all adult patients seen at Stanford University between 2/28/09 and 3/1/2023 with any clinical document containing “IgG4-related disease,” “IgG4-RD,” or “IgG4 disease.” Each chart was manually reviewed to verify the diagnosis. Cases were categorized as definite, probable, or possible IgG4-RD2. We included all patients with prior non-gated CT chest imaging. A radiologist with expertise in IgG4-RD and vasculitis reviewed the scans, and patients who had features concerning for possible CAI were recommended to obtain a gated CT of the heart or chest. After reviewing the confirmatory imaging, we calculated the prevalence of CAI, as well as the positive predictive value (PPV) for detecting CAI.

Results: Of the 250 IgG4-RD patients in the full cohort, 130 patients (52.0%) had prior non-gated chest imaging (Figure 1). Twenty patients (15.4%) had findings concerning for possible CAI. Four of the 20 patients could not be contacted due to departure from our healthcare system or death. Of the 16 remaining patients, 3 had a negative gated CT angiography (CTA) of the chest or heart, 4 had a positive gated CTA, and 7 had prior gated CTA studies obtained after the original non-gated CT chest, which were subsequently reviewed and were positive (representative images of CAI are shown in Figure 2). Additionally, 2 patients had such profound results on the initial non-gated CT chest they were deemed definitely positive without the need for a confirmatory gated CTA. As Table 1 demonstrates, patients with CAI were older (70 years vs 63 years), more likely to be male (77% vs 49%), more likely to be current smokers (23% vs 3%), more likely to have multiorgan disease (100% vs 58%), and had higher serum IgG4 concentrations (mean peak value 973 mg/dL vs 456 mg/dL). In total, 13 out of 16 patients who screened positive were confirmed to have CAI, resulting in a PPV of 81.3%. The prevalence of CAI in this cohort of patients was 13 out of 130 (10.0%).

Conclusion: By reviewing non-gated CT chest imaging to screen for IgG4-RD CAI, we observed a prevalence of CAI of 10% in our cohort. This is higher than what has been previously reported and likely represents a conservative estimate. Our results suggest that CAI is relatively common in IgG4-RD, and future studies are needed to determine which patients should be screened for CAI and whether the approach described herein has adequate sensitivity to be implemented as a screening test. References:Katz G, et al. Semin Arthritis Rheum. 2023;60:152184.Baker MC, et al. J Rheumatol. 2023;50(3):408-12.

Figure 1. Cohort selection.

Figure 2. IgG4-RD coronary artery involvement on computed tomography. Panel A demonstrates suspected right coronary artery thickening on a non-gated chest CT without IV contrast (large arrow), which is confirmed on gated CT angiography (Panel B; large arrow). Panel C demonstrates additional sites of disease, including the left main, left anterior descending, and proximal left circumflex (small arrows), which were not clearly apparent on the initial CT.

Table 1. Demographics and characteristics of IgG4-RD patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/prevalence-of-coronary-artery-involvement-in-igg4-related-disease-detected-by-non-gated-cross-sectional-imaging/