IgG-4 RD causing aortic regurgitation and complete AV block
The present case has been reported in the European Heart Journal - Case Reports.

Immunoglobulin G4-related disease (IgG4-RD) is a systemic disease characterized by the tumefactive lesions and infiltration of IgG4-positive plasma cells. IgG4-RD has been described in various organs, but rarely the aortic valve.

A 62-year-old man, receiving steroid therapy, who presented with general malaise, shortness of breath, and bradycardia. He had suspected IgG4-RD because of pancreatitis, lacrimal gland enlargement, and retroperitoneal fibrosis. An examination revealed a thickened aortic valve extending to the left ventricular outflow tract with severe aortic regurgitation and complete atrioventricular block.

He received intensive steroid therapy for a suspected IgG4-related aortic valve lesion. The complete atrioventricular block improved, but worsening aortic regurgitation caused congestive heart failure. He required replacement of the aortic valve.

A histopathological examination of the excised aortic valve leaflets revealed IgG4-positive lymphoplasmacytic infiltration with fibrotic tissue. The prosthetic valve was functioning well without leakage around the valve at the 1-year follow-up.

This case highlights the rare possibility that IgG4-RD of the aortic valve also causes significant aortic regurgitation. Conservative treatment with steroids may induce regression of the lesion and contribute to the stability of the prosthetic valve after surgery, but it may also exacerbate heart failure due to the progression of aortic regurgitation in patients with aortic valve lesions.

Learning points
• Immunoglobulin G4-related disease (IgG4-RD) of the aortic valve may cause aortic regurgitation and heart block. Steroid therapy is effective for regression of the lesion, but can exacerbate aortic regurgitation and cause heart failure.

• Regardless of whether serum IgG4 level normalizes, sustained increases in inflammatory markers during medication therapy for IgG4-RD may indicate the development of new lesions.

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