Background/Purpose: Myocardial dysfunction is reported in over half of systemic lupus erythematosus (SLE) patients, yet the underlying pathogenesis remains poorly understood. Endomyocardial biopsies (EMBs) are considered the gold standard for diagnosing cardiac involvement and myocarditis in inflammatory conditions, including SLE. However, EMBs are rarely performed in clinical practice and most of the histopathology reports in the literature consist of post-mortem data. We sought to describe the histopathologic findings of EMBs in SLE patients with active cardiac symptoms.

Methods: A retrospective review of histopathology reports was performed on SLE patients at Columbia University Medical Center who underwent EMBs from 1994-2017. SLE patients were identified by ICD-9 & 10 codes. EMBs, performed for evaluation of unexplained low ejection fraction suspicious for myocarditis, were similarly identified by procedure codes for cardiac pathology. Out of 1,994 SLE patients identified by ICD codes, 59 had cardiac pathology reports. The diagnosis of SLE was confirmed in 41/59 patients by chart review using ≥ 4 revised 1997 ACR classification criteria or SLICC classification criteria. Eleven histopathology reports were EMBs and the remaining were valvular specimens. Demographics, SLE characteristics, and cardiovascular disease risk factors were ascertained by chart review.

Results: Data from eleven SLE EMBs patients was reviewed (Table 1). Mean age was 37 ± 17; 82% were female, and median disease duration was 2.5 years (0-25.5). Anti-dsDNA and anti-SSA/Ro antibodies were present in 64% and 45%, respectively. Forty-five percent had hypertension, 27% had coronary artery disease, 9% had hyperlipidemia, and 36% had end-stage renal disease; none had diabetes or smoked. One patient had antiphospholipid antibody syndrome on anticoagulation. Mean ejection fraction was 37%. On histopathology, 91% had mild interstitial fibrosis, 82% had myocyte hypertrophy, 27% had organized blood clots, and 27% had a mild infiltration of lymphocytes and macrophages without clear evidence of myocarditis. None of the patients had vasculitis, endocarditis, ischemia, or amyloid deposition. Glycogen storage was observed in one patient.

Conclusion: EMBs are rarely performed in SLE. Inflammatory infiltrates were present in only 27% of all SLE EMBs and non-specific interstitial fibrosis and myocyte hypertrophy were the most common findings. These data suggest that EMBs have limited value in the diagnosis of cardiac involvement in lupus and support the need for alternative diagnostic approaches to SLE heart disease.

Table 1. Patient Characteristics.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/endomyocardial-biopsies-in-the-diagnosis-of-myocardial-involvement-in-systemic-lupus-erythematosus/