P208 PET-CT scanning of GCA patients: the additive role of opportunistic screening for cardiovascular disease in a high-risk population
Authors: Mulhearn Ben , Ellis Jessica , Foley Robert , Gunawardana Shannon , Wickramarachchi Rajika , Rodrigues Jonathan , Watkinson Oliver , Tansley Sarah , Graham Richard , Skeoch Sarah 
Published: April 2023

Abstract

Background/Aims
Cardiovascular disease (CVD) is well-recognised in giant cell arteritis (GCA) and thoracic aortic aneurysms (TAAs) are a late complication. Although the British Society for Rheumatology acknowledge the increased risk of CVD and TAAs, guidance for the management of GCA does not recommend antithrombotic agents or vascular screening due to lack of evidence. Positron emission topography (PET-CT) is commonly used for evaluation of large vessel vasculitis (LVV) in GCA. Although not routinely reported, additional measurements including aortic calibre and presence of coronary and aortic calcification can be assessed. LVV is known to be a risk factor for TAA. Therefore, this cohort represents an enriched population to evaluate for cardiovascular abnormalities. Our aims were to: estimate the prevalence of CV abnormalities on PET-CT scans in GCA; develop a standard operating procedure of CV parameters to improve the management of cardiovascular complications in conjunction with radiology and cardiology.

Methods
A retrospective review of PET-CT scans in GCA patients between 2016-2022 was undertaken. We determined the prevalence of CV abnormalities. Maximum diameter of the thoracic aorta and the presence of coronary and aortic calcification were reviewed by a PET-CT radiologist. Clinical characteristics and CV risk factors were evaluated. A standardised reporting protocol was developed for GCA PET-CT scans. A local guideline for the management of CV abnormalities was formulated.

Results
Fifty-two consecutive patients with GCA who had undergone PET-CT were identified. Most were female (40/51; 80%). Median age at diagnosis was 71 years (interquartile range [IQR] 63-75). Median time from GCA diagnosis to PET-CT scan was 20 months (IQR 4-38). Nine patients were diagnosed with GCA by PET-CT scan. Most GCA patients (32/51; 63%) were known to have CVRFs. 17/32 (53%) took an antithrombotic and/or anticoagulant, and 10/32 (31%) had a lipid lowering therapy. Original PET-CT scans reported coronary artery and/or aortic calcification in 6/51 (12%) GCA patients. Re-examination of PET-CT scans found coronary artery calcification in 38/51 (74%) and aortic calcification in 14/51 (27%) of all GCA patients. Coronary artery calcification was found in 27/32 (84%) of GCA patients known to have CVRFs, and 12/32 (38%) had evidence of aortic calcification. For GCA patients without CVRFs, 11/19 (58%) had evidence of coronary artery calcification and 2/19 (10%) had aortic calcification.

Conclusion
We observed a significant burden of cardiovascular abnormalities on PET-CT in GCA patients. Ten percent of patients with aortic dilation required follow up. A significant proportion of those with coronary calcification were not on primary prevention therapy. Importantly, 58% of patients without known CV risk factors were found to have coronary artery calcification. Given the burden of abnormalities identified we have now instituted a standardised reporting policy on CV abnormalities on PET-CT for GCA indications. Local policies have been developed for the management of thoracic aneurysms in GCA.
Disclosure
B. Mulhearn: None. J. Ellis: None. R. Foley: None. S. Gunawardana: None. R. Wickramarachchi: None. J. Rodrigues: None. O. Watkinson: None. S. Tansley: None. R. Graham: None. S. Skeoch: None.