Abstract 19163: A Rare Case of Pericarditis as an Initial Manifestation of Rheumatoid Arthritis

Abstract

Case Presentation: A 69-year-old male with a history of chronic recurrent pericarditis presented with a 3-week episode of chest pain. Despite treatment with ibuprofen, colchicine, prednisone, and anakinra, he experienced multiple flares upon attempting to wean off anakinra. His current workup revealed an elevated C-reactive protein and an echocardiogram showing a small pericardial effusion. Cardiac magnetic resonance imaging showed mild pericardial late gadolinium enhancement and increased pericardial signal on T2 STIR imaging, confirming a flare of recurrent pericarditis. The patient was started on rilonacept while being weaned off anakinra. During a follow-up after 3 months, the patient reported new onset polyarthralgia, prompting a referral to rheumatology. Rheumatoid factor was negative, but anti-citrullinated protein antibodies were positive, leading to a diagnosis of rheumatoid arthritis (RA). Azathioprine was added to the treatment regimen alongside rilonacept. Discussion: The patient's recurrent pericarditis was initially considered idiopathic but, with the subsequent RA diagnosis, it was suspected that RA may have been the underlying cause. While pericarditis is a known cardiac complication of RA, it is uncommon for pericarditis to be the initial manifestation of RA. Anakinra and rilonacept are both interleukin-1 (IL-1) inhibitors, with anakinra being FDA-approved for RA treatment. However, rilonacept has not been extensively studied in patients with RA. The case suggests that the use of certain medications may have masked RA symptoms, and as those medications were tapered, the RA symptoms became more evident. This case highlights the possibility of idiopathic pericarditis evolving into an autoimmune etiology, such as RA, over time. The combination of rilonacept and azathioprine for treating RA has limited evidence, emphasizing the need for further research in this area.