STATIN INDUCED NECROTIZING AUTOIMMUNE MYOPATHY WITHOUT CONCURRENT STATIN USE: YET ANOTHER SEQUELA OF COVID-19?

Background:

Exposure to a statin is a major risk factor for an autoimmune myopathy called statin induced necrotizing myopathy (SINAM). Viruses have been described to be a trigger for autoimmunity and SARS-CoV-2 may be no different. Here we present a case of SINAM in a patient after developing COVID-19 infection and without use of a statin for a year.

Case:

54-year-old man with history of hyperlipidemia, who had stopped all medications including atorvastatin for a year, presented to the clinic with worsening upper and lower extremities weakness for two months. His weakness began after having symptoms for COVID-19 infection with fever, chills, myalgia. Despite improvement in viral symptoms, weakness persisted and included difficulty rising from a chair, chewing and swallowing. He lost 15 lbs. Physical examination (PE) revealed temporal and facial muscle wasting with significant proximal muscle weakness. Lab results showed Creatinine Kinase (CK) of 14,501 and positive antibodies (AB) against 3-hydroxy-3-methylglutaryl CoA reductase (anti HMG-CoA) with normal TSH, ESR, and negative ANA. Myositis AB panel was negative. Electromyography showed widespread denervation with early recruitment and low amplitude action potential concerning for severe myositis. Ultimately, muscle biopsy revealed necrotizing myopathy with minimal inflammation.

Decision-making:

A diagnosis of SINAM was made and the patient was immediately started on high dose steroids and referred to rheumatologist for immunotherapy.

Conclusion:

Statins can produce a type of myositis that resolves once the medication is removed but it can also produce SINAM which is a necrotizing myositis with anti HMG-CoA antibody production. Symptoms of SINAM have been reported in patients actively taking a statin and should be highly suspected when symptoms do not improve with stopping the statin. This case demonstrates an even rarer finding of SINAM in a patient who had stopped his statin long before developing symptoms. In patients with symptoms of proximal muscle weakness and elevated CK levels, any exposure to statin, current or past, must be identified and warrants checking for anti HMG-CoA levels.