In 2019, we conducted an intervention study, MUSE. The purpose of the study is to investigate the effect of statins on muscle symptoms in patients who report such complaints. We will also examine if statin metabolites in blood can be used to detect genuine statin-dependent muscle side effects. We reviewed the hospital records of nearly 1000 patients at the hospitals in Drammen and Vestfold who had acute myocardial infarction between 2016-2019. Of these, 77 patients who reported muscle side effects were randomized to 7 weeks of double-blind treatment with atorvastatin 40 mg/day and 7 weeks of treatment with an identical placebo tablet in a random sequence. Patients reported muscle symptoms weekly in a diary throughout the study period. At the start of the study and after each 7-week treatment period, blood samples were taken for analysis of statin metabolites, cholesterol, inflammatory markers, and genes potentially significant for statin metabolism. Patients also completed a questionnaire about cholesterol treatment and adherence, psychological factors, and the location and nature of muscle symptoms.

In 2020, we conducted a new intervention study, MUSE follow-up. The purpose of this study was to gain new knowledge about the effects of statins in muscle tissue and to investigate whether we can find markers in blood or muscle that can be used to detect genuine muscle side effects of statins. A selection of patients from the MUSE study with (15 patients) and without (15 patients) identified atorvastatin-dependent muscle side effects underwent a new 7-week treatment with atorvastatin 40 mg/day followed by 7 weeks without statins. Muscle symptoms were reported weekly in a diary throughout the study period, and we collected blood samples and tissue samples from the thigh muscle for analysis of statin metabolites and other biomarkers (lipids, proteins, genetic material) that might be significant for muscle side effects. We also aimed to examine the muscle samples under a microscope to determine if there are changes in the structure of muscle cells or surrounding tissue.