Research Day
STATIN-ASSOCIATED NECROTIZING AUTOIMMUNE MYOPATHY
Document Type
Abstract
Date
2021
Abstract
Introduction: Cardiovascular disease causes significant mortality in the United States and statins are important drugs in its prevention. They are generally safe and tolerated but may rarely cause toxic myopathy which improves on discontinuation of the drug. In very rare cases, 2-3 per 100,000 people, develop an autoimmune necrotizing myopathy.
Case description: A 67-year-old woman with diabetes, hyperlipidemia, hypertension developed proximal upper and lower muscle weakness and was found to have an elevated CPK in the rhabdomyolysis range. As she was on atorvastatin it was felt she may have developed statin-induced toxic myopathy and the drug was discontinued. Her weakness continued to worsen resulting in her falls and difficulties to walk. Her CPK levels, 5 months later, were still elevated in 4000s. EMG of her proximal muscles demonstrated amyopathic process with marked membrane instability characteristic of inflammatory myopathy. She tested positive for autoantibodies against 3-hydroxy-3-methylglutaryl coenzyme A reductase. Subsequent muscle biopsy showed evidence of scattered muscle necrosis with sparse inflammatory response. She was treated with intravenous immunoglobulin (IVIG) and prednisone with taper and addition of a second-line immunosuppressive agent. Her symptoms improved markedly and her CPK levels declined in the lower 1000s.
Discussion: Autoimmune HMGCR myopathy caused by statins is very rare and challenging to treat. Early diagnosis is important because delays in treatment can cause irreversible muscle damage with function loss.