Migratory Arthritis and Heart Block in an Adult: A Forgotten Diagnosis Revisited.

Acute rheumatic fever (ARF) is an abnormal immunologic response to group A streptococcus (GAS) infections, most commonly tonsillopharyngitis. While ARF most often occurs in children, it is rare in adults. Carditis is a recognized manifestation of ARF, though it is uncommon in adult presentations. We present a case of a 35-year-old male with fever, migratory polyarthritis, and subclinical carditis in the form of a prolonged PR interval, mild aortic regurgitation (AR), and trace mitral regurgitation (MR) detected on echocardiography. Further investigations revealed an erythrocyte sedimentation rate (ESR) of 101 mm/hour and markedly elevated antistreptolysin O (ASO) titers of 1,600 IU/mL. The diagnosis of ARF was made based on the 2015 revised Jones criteria, which included one major criterion (migratory polyarthritis), three minor criteria (fever, elevated ESR, and prolonged PR interval), and supportive evidence of recent streptococcal infection. Other causes of arthritis, such as septic arthritis, were ruled out. The patient responded well to nonsteroidal anti-inflammatory drugs (NSAIDs) and was treated with intramuscular penicillin G for eradication, followed by lifelong azithromycin prophylaxis for recurrence prevention. This case highlights the importance of considering ARF in adult patients presenting with migratory arthritis and conduction abnormalities.