Article Type : Case Report
Title : New-Onset Atrial Fibrillation Associated with Mycophenolate Mofetil in Systemic Sclerosis: A Case Report
Abstract : Mycophenolate mofetil (MMF) is commonly used in the treatment of systemic sclerosis (SSc) due to its immunosuppressive and antifibrotic properties. While MMF is generally well tolerated, cardiovascular complications have been rarely reported. We present a case of a 54-year-old female with systemic sclerosis who developed a clinically significant arrhythmia following MMF initiation. The patient experienced palpitations and dizziness, with electrocardiography (ECG) revealing atrial fibrillation with a rapid ventricular response. A comprehensive evaluation ruled out other potential causes, implicating MMF as the likely contributor. Upon MMF discontinuation, the arrhythmia resolved. This case highlights the importance of monitoring for cardiac arrhythmias in patients on MMF therapy, particularly in those with pre-existing cardiovascular risk factors. Clinicians should be aware of this potential adverse effect and consider alternative treatment strategies when necessary.
Introduction : Systemic sclerosis (SSc) is a chronic autoimmune connective tissue disease characterized by fibrosis, vasculopathy, and immune dysregulation [1]. Mycophenolate mofetil (MMF) is widely used as an immunosuppressive agent in SSc to manage interstitial lung disease and skin fibrosis [2-4]. Though MMF is generally well tolerated, rare adverse effects, including hematologic, gastrointestinal, and infectious complications, have been reported [5-7]. Cardiovascular effects, particularly arrhythmias, remain poorly documented [8]. We report a case of new-onset atrial fibrillation in a patient with SSc following MMF initiation.
Case Presentation : A 54-year-old female with a 7-year history of limited systemic sclerosis presented with progressive skin tightening, Raynaud’s phenomenon, and mild interstitial lung disease. She was initiated on MMF at 500 mg twice daily, gradually titrated to 2 g daily over four weeks.
Two weeks after reaching the target dose, the patient developed palpitations and dizziness. Her heart rate was 130 beats per minute, and blood pressure was 110/70 mmHg. An ECG showed atrial fibrillation with a rapid ventricular response. Laboratory workup, including thyroid function tests, electrolytes, and inflammatory markers, was unremarkable. A transthoracic echocardiogram showed normal left ventricular function without valvular abnormalities.
MMF was discontinued, and rate control was achieved with beta-blockers. Within a week, the patient’s rhythm reverted to normal sinus without requiring cardioversion. She remained arrhythmia-free on follow-up, suggesting a potential causal link between MMF and the arrhythmia.
Discussion : While MMF is not commonly associated with arrhythmias, its immunomodulatory effects may contribute to autonomic dysregulation or direct myocardial toxicity [1-6]. Previous reports have linked MMF to bradyarrhythmias, but this case suggests a possible role in triggering atrial fibrillation [4]. Other potential contributors, such as infection, thyroid dysfunction, and electrolyte imbalance, were excluded, strengthening the association [7-8].
Clinicians should maintain a high index of suspicion for cardiac arrhythmias in patients treated with MMF, particularly those with underlying cardiovascular risk factors. Further research is needed to establish the exact mechanism and incidence of this adverse effect.
This case underscores the need for vigilance when prescribing MMF in patients with systemic sclerosis. Close cardiac monitoring should be considered in those developing palpitations or other cardiovascular symptoms. Alternative immunosuppressive therapies may be warranted in susceptible individuals.
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