Objective:

To study statin-related muscle complications in patients with hereditary muscle diseases.

Background:

Statins, known for their muscle-related complications, have been reported to unmask myopathic symptoms in rare patients with hereditary muscle diseases. Studies on their safety and tolerability in patients with hereditary muscle diseases are lacking. 

Design/Methods:

We reviewed medical records (2013-2023) to identify patients with myotonic dystrophies (DM1 and DM2), facioscapulohumeral dystrophy (FSHD), limb-girdle muscular dystrophy (LGMD), and mitochondrial myopathies (MM). We included patients who had ever taken statins. 

Results:

We included 134 patients (36 DM1, 47 DM2, 23 FSHD, 10 LGMD, and 18 MM), in 39 of whom statins were discontinued because of newly diagnosed myopathy (13), new or worsened muscle symptoms (19), or other (7). Ninety-five patients were still on statin at last follow-up. Muscle complications occurred in 31/134 (23.1%) patients (8 DM1, 10 DM2, 7 FSHD, 3 LGMD, and 3 MM), encompassing isolated myalgia (23), isolated weakness (1), weakness and myalgia (6), and rhabdomyolysis (1). CK was markedly elevated in a rhabdomyolysis patient (MM), mildly elevated in 3 patients, and normal in others. Statins unmasked myopathy symptoms that led to a diagnosis in 5/31 patients (1 DM1, 1 FSHD, and 3 MM), in whom muscle complications (1 myalgia, 1 weakness, 2 combined, and 1 rhabdomyolysis) persisted despite statin discontinuation. Eight patients with statin-related symptoms underwent HMGCR antibody testing, all of which were negative.

Conclusions:

Statin-related muscle complications are typically mild in this patient population with hereditary muscle diseases and occur with the same frequency as in the general population, except for a more frequent occurrence of rhabdomyolysis in mitochondrial myopathy patients.  Rarely, statin initiation can unmask muscle symptoms in asymptomatic patients with hereditary muscle diseases. Persistent muscle symptoms after statin discontinuation should prompt consideration of not only immune-mediated necrotizing myopathy, but also hereditary muscle diseases.