engleski

Delayed onset of Statin-induced necrotizing autoimmune myopathy

Learning objective Statin-induced necrotising autoimmune myopathy (SINAM) is a relatively new term, which describes a rare and severe complication of statin therapy and, because of its clinical presentation, complicated course, and the expected increased statin use in the future, an extremely challenging phenomenon. Case A 73-year-old woman was admitted to the hospital with progressive symmetrical muscle weakness in the legs. The laboratory test showed elevated liver enzymes, an elevated creatine kinase of 4830 U/L and Troponin T of 405 ng/L. The heart diagnostic was negativ. MRI of the legs showed signal alterations of several muscles. The biopsy of the musculus rectus femoris was performed – the result corresponded to the morphological picture of the necrotizing autoimmune myopathy. The patient confirmed an earlier statin intake. However, the medication has been stopped 18 months before the current hospitalization because of elevated liver enzymes. The blood analysis showed positive antibodies against anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (anti-HMGCR). The cortisone and immunoglobulin therapy quickly improved the patient's clinical condition. Discussion SINAM is a very rare form of the myopathy (approximately 2-3 cases of every 100, 000 statin-patients), with potentially severe consequences and very often unrecognized symptoms, mostly present in patients above the age of 50 years. The mechanisms of the emergence of SINAM are still poorly understood. The timing of the onset of this disease cannot be defined - as a rule, the disease manifests itself within 10-20 years of the start of statin administration. The laboratory findings showed the elevation of the creatine kinase more than 10-fold greater than normal. The finding of anti-HMGCR antiboides is a valuable test to confirm the suspicion of SINAM. The muscle biopsy with a finding of necrotic muscle fibers and mild or absent inflammatory cell infiltration is an indispensable method, which together with anamnesis, clinical symptoms, laboratory findings, and imaging diagnostic methods fills the puzzle of diagnostic procedures A such a late onset of symptoms as in our case confirms the assumption that pathophysiological mechanisms of SINAM are still unclear and must be taken into account in the differential diagnosis of every progressive muscle weakness independently of the time of the statin uptake.

statin, myopathy, therapy

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