Myocarditis in Systemic Lupus Erythematosus Diagnosed by F-fluorodeoxyglucose Positron Emission Tomography

Objectives: Cardiovascular diseaseand heart failure (CHF) are leading causes of death in systemic lupus erythematosus (SLE). The underlying mechanisms for increased CHF in SLE are unclear but myocardial inflammation and lupus myocarditis (LM) may play a role. We propose that F-fluorodeoxyglucose-positron emission tomography (F-FDG-PET)/CT can help diagnose LM.

Methods: This report describes eight patients with presumed LM; five patients were evaluated due to active cardiorespiratory symptoms and three patients were participating in a pilot study to determine the prevalence of subclinical myocarditis in SLE. Clinical characteristics, laboratory and cardiac testing including electrocardiography (ECG), transthoracic echocardiogram (TTE), coronary artery evaluation as well as F-FDG-PET/CT imaging are discussed.

Results: Four patients were African American and the others were Hispanic. Half presented with chest pain; 37% had dyspnoea and 25% were asymptomatic. The median SLE Disease Activity Index (SLEDAI-2K) was 5 (2-18) and SLICC Damage Index (SDI) 0.5 (0-5). The median troponin level was 0.08 ng/mL (0-0.9). The most common ECG findings were non-specific ST-T wave abnormalities (n=5). Fifty per cent of the patients had a decreased ejection fraction on TTE and all patients had diffuse myocardial FDG uptake on F-FDG-PET/CT consistent with myocardial inflammation.

Conclusion: This case series is the first to describe the use of F-FDG-PET/CT in the diagnosis of LM and discuss the clinical characteristics and cardiac findings of eight patients with LM supporting the role for cardiac F-FDG-PET/CT in its diagnosis.