Lymphocytic myocarditis with suspected granulomatosis with polyangiitis presenting as cardiogenic shock, restrictive cardiomyopathy and complete heart block

We report a case of restrictive cardiomyopathy from lymphocytic myocarditis in a patient with suspected granulomatosis with polyangiitis (GPA). The case was complicated by complete heart block and renal failure. The diagnosis was supported by upper airway involvement, elevated serum serine proteinase 3 antibodies, and endomyocardial biopsy with lymphocytic infiltration. The patient responded appropriately to aggressive immunosuppressive therapy.