Beyond the Usual Suspects: IgG4-Related Disease as a Rare Culprit in Cardiac Valvular Disorders.

Cardiologists consider degenerative or infectious causes when evaluating valvular heart disease. However, the role of autoimmune disorders, though less frequent, remains clinically significant. This report describes a young male patient presenting with persistent coronary disease and a suspected valvular cusp perforation initially attributed to infective endocarditis, which ultimately proved to be a manifestation of IgG4-related disease. IgG4-related disease is a rare condition, more prevalent in Asian populations, that typically affects the pancreas, salivary glands, lacrimal glands, and the retroperitoneum. Cardiac involvement, although uncommon, can present in various ways, including pericarditis, pulmonary arterial hypertension, valve dysfunction, cardiac pseudotumor, and coronary disease. Diagnosing and managing IgG4-related cardiac involvement requires heightened clinical suspicion, serological and histopathological assessment, and prompt interdisciplinary collaboration. Notably, involving rheumatologists in the management of these rare yet impactful autoimmune cardiac diseases is essential.