What autoimmune diseases can cause myocarditis?

Autoimmune Causes of Myocarditis

Systemic autoimmune diseases and vasculitides are well-established causes of myocardial inflammation, with rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, sarcoidosis, and inflammatory myopathies being the most clinically significant entities. 1

Major Autoimmune Diseases Associated with Myocarditis

Rheumatoid Arthritis

• Myocardial inflammation occurs in 46-55% of patients with rheumatoid arthritis, demonstrating focal late gadolinium enhancement (LGE) on cardiac MRI and larger areas of myocardial edema compared to controls. 1
• Patients show elevated native T1 mapping and extracellular volume (ECV) on advanced cardiac imaging, indicating active inflammation. 1

Systemic Lupus Erythematosus (SLE)

• SLE-associated myocarditis correlates directly with disease activity, with increased T2 ratios and EGE ratios on cardiac MRI. 1
• LGE is present in approximately 45-69% of SLE patients when systematically evaluated with cardiac MRI. 1
• Diffuse coronary vessel wall contrast enhancement occurs in 89% of patients, indicating widespread vascular inflammation. 1

Systemic Sclerosis (Scleroderma)

• Focal LGE appears in 17.5-53% of systemic sclerosis patients, with variation depending on study methodology and disease duration. 1
• The pattern typically involves the basal and midseptum and right ventricular insertion sites. 1
• Native T1 and ECV correlate with disease activity and abnormal systolic and diastolic strain parameters. 1

Cardiac Sarcoidosis

• Cardiac involvement occurs in 19-26% of patients with extracardiac sarcoidosis, substantially higher than the 12% identified by traditional Japanese Ministry of Health criteria. 1
• This represents a critical diagnostic consideration as it requires specific immunosuppressive therapy. 1

Inflammatory Myopathies

• Polymyositis, dermatomyositis, and other inflammatory myopathies carry significant risk for myocarditis, which is historically underrecognized due to subclinical presentation. 2
• Cardiac involvement is associated with poor prognosis and requires aggressive immunosuppressive therapy. 2
• The anti-Jo1 syndrome specifically can present with acute myocarditis as the heralding manifestation. 3

Additional Autoimmune and Inflammatory Entities

Vasculitides

• Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome) causes eosinophilic myocarditis with characteristic diffuse subendocardial LGE patterns, distinct from the subepicardial distribution of viral myocarditis. 1, 3
• Behçet's disease can be accompanied by myocarditis as part of its systemic inflammatory manifestations. 4

Other Autoimmune Conditions

• Mixed connective tissue disease can present with acute myocarditis. 3
• Antiphospholipid syndrome has been documented as a cause of myocarditis. 3
• Adult-onset Still's disease may have myocarditis as its initial presentation. 3

Giant Cell Myocarditis

• Giant cell myocarditis represents a fulminant autoimmune form requiring immediate immunosuppressive therapy to improve outcomes. 1
• CMR shows large areas of high signal intensity in various, sometimes atypically subendocardial layers, similar to severe sarcoidosis. 1

Clinical Recognition Features

Key Diagnostic Clues for Autoimmune Etiology

When evaluating acute myocarditis, the presence of pericardial effusion, absence of chest pain, and elevated CRP levels at presentation are independently associated with underlying autoimmune disease. 3

• Pericardial effusion is more common in autoimmune myocarditis compared to viral or idiopathic forms. 3
• Elevated inflammatory markers (CRP) suggest systemic autoimmune process rather than isolated viral infection. 3
• Approximately 6.9% of acute myocarditis cases reveal previously undiagnosed autoimmune disease. 3

Pathophysiology and Emerging Mechanisms

Autoreactive T cells specific for cardiac myosin play a pivotal role in autoimmune myocarditis, with these cells capable of bypassing thymic selection and persisting even in healthy individuals. 5

• IL-17A-mediated inflammation drives progression from acute myocarditis to inflammatory dilated cardiomyopathy. 6
• The TRIM21-TRAF3 pathway amplifies IL-17A signaling in cardiac fibroblasts, establishing a self-reinforcing inflammatory loop. 6

Treatment Implications

All patients with myocarditis due to autoimmune disorders require immunosuppressive therapy, typically including corticosteroids with or without additional immunosuppressive agents. 3, 7

• Left ventricular ejection fraction normalizes in the vast majority of autoimmune myocarditis patients with appropriate immunosuppression. 3
• Despite potentially severe presentation (LVEF <30% in 33% of cases), prognosis is generally favorable under specific treatment. 3
• Immunosuppression is specifically indicated for eosinophilic myocarditis, giant cell myocarditis, and myocarditis due to systemic autoimmune disorders. 7