Rheumatoid arthritis (RA) is the most likely cause of this patient's pericarditis. RA is an independent risk factor for both coronary artery disease and heart failure; patients with severe extra-articular disease are at particularly increased risk of cardiovascular death. Pericarditis is the most common cardiac manifestation of RA and is often asymptomatic. Approximately one third of patients with RA can be found to have an asymptomatic pericardial effusion, and 10% of patients with RA will have symptomatic pericarditis at some point during the course of their disease. Most of those with symptomatic disease have a positive rheumatoid factor and active synovitis; however, when symptomatic, the manifestations are likely to be similar to those of any other cause of pericarditis. Diagnosis is most often made by confirming two of three classic findings: chest pain, often with a pleuritic component; friction rub; and diffuse ST-segment elevation on electrocardiogram.

Ankylosing spondylitis is a form of spondyloarthritis that manifests primarily by axial inflammation and bony ankylosis (fusion across joints). Inflammatory arthritis involvement of the hands tends to present as “sausage digits” rather than the symmetric polyarthritis seen in RA. Although conduction defects and aortitis with dilatation of the aortic valve ring and aortic regurgitation occur, pericarditis is not seen in patients with ankylosing spondylitis.

Polymyalgia rheumatica occurs in patients over the age of 50 years and causes diffuse achiness at the neck, shoulder girdle, and pelvic girdle. It is rarely associated with synovitis and is not associated with pericarditis.

Psoriatic arthritis is associated with an increased risk of coronary artery disease, as is RA. It can also cause a symmetric polyarticular inflammatory arthritis involving the small joints of the hands. However, psoriatic arthritis is not a common cause of pericarditis.