Statins in Genetic Myopathies

Objectives: Statins are widely prescribed lipid-lowering agents, but their safety and tolerability in patients with underlying genetic myopathies remain uncertain. We aimed to study statin safety and tolerability in genetic myopathies using a large retrospective cohort. Methods: We conducted a retrospective study in patients with myotonic dystrophy type 1 (DM1) and type 2 (DM2), facioscapulohumeral dystrophy (FSHD), limb-girdle muscular dystrophy (LGMD), and metabolic or mitochondrial myopathies who were exposed to statins. Results: We included 135 patients (36 with DM1, 46 with DM2, 22 with FSHD, 6 with LGMD, 17 with mitochondrial myopathy, 6 with glycogenosis, and 2 with disorders of fatty acid oxidation or carnitine transport). A total of 44 patients discontinued statins, most often for statin-associated muscle symptoms (SAMS; n = 20). SAMS occurred in 36 of 135 patients (26.67%; 8 with DM1, 10 with DM2, 7 with FSHD, 3 with LGMD, 4 with mitochondrial myopathy, and 4 with metabolic myopathy). Myalgias were the most frequent SAMS (n = 29). Rhabdomyolysis occurred in 4 patients (1 with mitochondrial myopathy and 3 with McArdle disease). Statins unmasked myopathy in 6 of 36 patients. No patient developed immune-mediated necrotizing myopathy. Discussion: SAMS are generally mild and occur at a frequency similar to the general population in common genetic myopathies, except increased rhabdomyolysis in mitochondrial myopathies and McArdle disease. Statins are generally safe, though not well tolerated, and could be used when closely monitored in several genetic myopathies. In mitochondrial and metabolic myopathies, their use should be approached with caution because of the potential risk of rhabdomyolysis.