Myopericarditis in Systemic Lupus Erythematosus Unmasking a Concomitant Diagnosis of Marfan Syndrome: A Case Report

Cardiovascular complications represent a major source of morbidity and mortality in systemic lupus erythematosus (SLE). While pericarditis is common, acute myopericarditis leading to significant systolic dysfunction is a less frequent but potentially life-threatening manifestation. The diagnostic evaluation can be complicated by overlapping clinical features and the presence of underlying, undiagnosed comorbidities. Hereditary connective tissue disorders, such as Marfan syndrome, present their own spectrum of cardiovascular risks, and their coexistence with autoimmune diseases like SLE is rare and poses significant diagnostic and therapeutic challenges.

We present the case of a 32-year-old woman with a long-standing diagnosis of SLE who was admitted with new-onset heart failure. Her symptoms included progressive dyspnea and pleuritic chest pain. The initial workup revealed active systemic inflammation, a newly reduced left ventricular ejection fraction of 44%, and a significant fusiform aneurysm of the ascending aorta (4.4 cm) associated with a bicuspid aortic valve. Cardiac magnetic resonance imaging was highly suggestive of active myopericarditis. While the initial findings were attributed to her lupus, the significant aortopathy in a young patient, combined with high myopia and a slender build, prompted further investigation. A formal clinical evaluation confirmed a diagnosis of Marfan syndrome based on the revised Ghent nosology. The patient responded favorably to intensified immunosuppression for her myopericarditis and was concurrently started on guideline-directed medical therapy for her aortopathy.

This case underscores the importance of maintaining a broad differential diagnosis in complex clinical presentations. The diagnosis of lupus myopericarditis was complicated and ultimately overshadowed by the unmasking of Marfan syndrome, a finding that fundamentally altered the patient's long-term prognosis and management strategy. This report highlights the critical need for a multidisciplinary approach and illustrates how a seemingly straightforward complication of a known disease can be the gateway to identifying a second, life-altering diagnosis.