Complete Atrioventricular Block in an HLA-B27-Positive Woman Without Overt Spondyloarthritis.

BACKGROUND: Complete atrioventricular block (CAVB) in adults younger than 50 years warrants investigation for inflammatory, infiltrative, infectious, autoimmune, and inherited disorders. Human leukocyte antigen B27 (HLA-B27)-associated conduction disease without overt spondyloarthritis is exceptionally rare. CASE SUMMARY: A 43-year-old physically active woman presented with symptomatic CAVB requiring dual-chamber pacemaker implantation. She had recurrent HLA-B27-positive anterior uveitis and Hashimoto thyroiditis but no clinical evidence of spondyloarthritis. Cardiac magnetic resonance imaging, fluorodeoxyglucose positron emission tomography, comprehensive genetic testing, and an extensive autoimmune evaluation were unrevealing, supporting a diagnosis of exclusion. DISCUSSION: Although atrioventricular conduction abnormalities are recognized in ankylosing spondylitis, isolated CAVB associated with HLA-B27 in the absence of overt spondyloarthritis has rarely been reported. This case broadens the recognized clinical spectrum of HLA-B27-associated disease and highlights recurrent HLA-B27-positive uveitis as a potential diagnostic clue in otherwise unexplained CAVB. TAKE-HOME MESSAGES: HLA-B27 testing should be considered in selected younger patients with unexplained CAVB and suggestive immune-mediated features. A multidisciplinary evaluation is essential after exclusion of structural, inflammatory, infectious, autoimmune, and inherited causes.