A rare bird: Avonex ® -induced pericardial effusion

Abstract Introduction There are multiple causes of pericardial effusion, including drugs. Avonex® (interferon beta-1a) is an immunomodulator used for the treatment of multiple sclerosis. Adverse cardiac effects associated with the use of Avonex® are exceedingly rare. To date, only one case has been reported by the United States Food and Drug Administration, associating the use of Avonex® with the development of pericardial effusion. We report the second such case. Case report A 44-year-old woman with a history of multiple sclerosis, asthma and schizophrenia presented to the Emergency Department with increasing shortness of breath for 2 months, which had acutely worsened that morning, orthopnoea and an unintentional weight loss of 10 pounds over the last 6 months. On examination, the patient was found to be short of breath but haemodynamically stable. Notable findings included bilateral wheezing, jugular venous distension and pulsus paradoxus. An electrocardiogram showed a normal sinus rhythm without electrical alternans. Chest radiograph revealed cardiomegaly; a transthoracic echocardiogram showed a large pericardial effusion with evidence of increased pericardial pressure and impending cardiac tamponade. Additional history revealed that the patient had been started on Avonex® 30 mcg once weekly several months prior. A comprehensive work to exclude all potential causes of pericardial effusion, including connective tissue disorders and infectious aetiologies, proved unrevealing. Surgical drainage was performed. A cytological examination of the pericardial fluid revealed benign mesothelial cells; tissue examination confirmed focal mesothelial hyperplasia. A tuberculin skin test was negative. Computed tomographic scanning of the chest, abdomen and pelvis did not show any evidence of an occult malignancy. Conclusion The patient and her neurologist were alerted to the possibility of Avonex®induced pericardial effusion due to the lack of evidence for other aetiologies. Despite the relative dearth of data on Avonex®-related pericardial effusion, this diagnosis is one that merits consideration to prevent potential morbidity and mortality.