7T Magnetic Resonance Spectroscopy and Skeletal Muscle Biopsy Findings in Statin
Phase: PHASE4
Conditions: Muscle Cramp, Ache, Weakness, Muscle, Statin Adverse Reaction
Sponsor: University of Texas Southwestern Medical Center

Official title:   Statin-associated muscle symptoms: in vivo and in vitro 
studies of mitochondrial function 
NCT number: NCT04507373   
IRB approved date: 04/25/2018 

1. Project Description 
 
1.a Overview. Over 40 million Americans take statins to reduce their risk of atherosclerotic 
cardiovascular disease (ASCVD). Unfortunately, 10 to 20% stop taking them due to statin-as-
sociated muscle symptoms (e.g. pain, aches, weakness, cramps, or stiffness) (1, 2). The path-
ophysiology of these statin-associated muscle symptoms (SAMS) has remained elusive. Con-
sequently, no objective diagnostic method exists, causing confusion for patient and providers 
since muscle symptoms can often be multifactorial.   
The overall objectives of this project are to identify the underlying cause of SAMS and 
establish an in-vivo imaging technique to detect SAMS.  The central hypothesis of this pro-
posal is that statins directly inhibit mitochondrial function in SAMS patients. Our ra-
tionale is based on our own preliminary data indicating that simvastatin – the most common 
statin to cause SAMS – can directly inhibit oxidative phosphorylation (OXPHOS) in mice. Since 
such changes can be detected in vivo in humans utilizing 31P magnetic resonance spectros-
copy (MRS) techniques, we will use a state-of-the art 7 Tesla (7T) MRS instrument to study the 
soleus muscles of SAMS patients. Additionally, we will validate the MRS findings by doing 
functional studies in muscle biopsy specimens.  
We propose double-blind randomized, placebo-controlled pilot study in 15 SAMS pa-
tients and 15 controls. Study participants will be treated with simvastatin 40 mg daily or pla-
cebo for 10 weeks. We will perform 7T MRS of soleus muscles at randomization and either at 
first complaint of muscle symptoms or at the end of 10 weeks if no muscle symptoms occur, 
whichever occurs first. Quadriceps muscle biopsies will also be done immediately following the 
second MRS scan.  
 
1.b What is the scientific problem that will be addressed and why is this important?  
SAMS are prevalent and limit the benefits of lipid lowering.  Statins are the second 
most commonly prescribed medication class in the US (3). Unfortunately, muscle injury – rang-
ing from mild muscle aches to life-threatening rhabdomyolysis – limits their use. Based on ob-
servational data, 10-20% of statin users stop treatment within the first year of the initial pre-
scription, citing SAMS as the primary reason (1, 2). Even among adherent statin users, one-
third experience interruptions in therapy due to SAMS (4).  
The current paradigm for treating SAMS patients is to diagnose subjectively and use 
trial-and-error approaches to reestablish therapy. These reestablished statin therapy are often 
at lower doses or with less potent statins, resulting in under-treatment (5-7). Also, since new 
lipid lowering agents (e.g. PCSK9 inhibitors) are expensive, payers often are unclear as to 
whether to cover the cost for patients with subjective com-
plaints. 
The major gap in knowledge is the effect of 
statins on muscles. The pathophysiology of SAMS re-
mains unclear. Human genetic studies have implicated 
genes in hepatocyte drug transport pathways (8), but have 
failed to provide insight into what is occurring in muscle tis-
sue. Translational studied have raised several possibilities 
(e.g the roles of Coenzyme Q10, Vitamin D, and circulating 
cholesterol levels), but results of clinical trials and human 
genetic studies have failed to support any of these (9-15). 
Statins may have an off-target effect: inhibition of 
mitochondrial function. Our preliminary data indicate that 
simvastatin lactone (the form that is highly cell permeable) 
Figure 1: Oxygen consumption rates (OCRs) from mi-
tochondria (0.1mg) isolated from wild type mouse 
skeletal muscle (tibialis anterior) treated with vehicle 
or simvastatin (lactone, 100uM) in the presence of 
complex I substrates (glutamate/malate). Drugs (ADP, 
oligomycin (oligo), CCCP, antimycin A(antA)) were in-
jected at times indicated. 

reduces oxygen consumption rates in isolated mitochondria (Figure 1). Our findings are con-
sistent with prior in silico data identifying a binding site for simvastatin in mitochondrial complex 
III (16). 
 
1.c What are the innovative or high-risk, high-reward approaches that, if successful, 
might lead to paradigm-shifting results? 
We will be able to correlate 7T MRS findings to studies of mitochondrial structure, 
function, and gene expression. The studies proposed here will allow for an integrated under-
standing of in vitro and in vivo changes induced by statins. If our hypothesis is correct, this 
work will lead to objective markers (e.g. MRS signals) that can be used to detect SAMS. 
Such a tool would shift the current paradigm (i.e. subjective diagnosis) by providing a tool to 
help providers, patients, and payers determine whether a statin is truly the cause of muscle 
symptoms. Such a tool could also be used to identify appropriate patients for further studies 
and follow their therapeutic response.  
 
1.d Does the project address a critical barrier to progress in the field? 
Human studies are required since no adequate animal model exists. SAMS has 
been difficult to induce in preclinical models with statins other than cerivastatin (17-20), per-
haps because of lack of muscle exposure when statins are given systemically to animals.  
No standardized diagnostic criteria exist for SAMS. The status quo as it pertains to 
SAMS is to diagnose patients based on their subjective complaints, resulting in confusion for 
patients, providers, payers, and clinical investigators. Statin withdrawal and rechallenge is of-
ten advocated as a diagnostic tool (21), but no evidence-based standardized protocol exists,  
the sensitivity and specificity remains unknown, and the outcome (self-reported muscle symp-
toms) remains subjective. A few commercially available diagnostic tests may be used for 
SAMS patients: blood creatine kinase (CK) levels, solute carrier organic anion transporter fam-
ily member 1B1 (SLCO1B1) rs4149056 genotype, and antibodies to 3-hydroxy-3-methlyglu-
taryl coenzyme A reductase (HMGCR). However, only 5% of SAMS patients develop elevated 
CK levels, SLCO1B1 rs4149056 genotype only predicts the risk of extreme elevations in CK in 
patients on simvastatin (8, 22, 23), and antibodies to HMGCR are responsible only for cases 
with severe CK elevations (greater than 1000 U/L) that fail to resolve after statins are with-
drawn (24). Thus for 95% of SAMS patients, no diagnostic test helps diagnose SAMS. 
The proposed research addresses this critical barrier to progress in the field by utilizing 
a 7T MRS instrument to develop an in vivo technique that will objectively diagnose SAMS, ef-
fectively removing a major roadblock for the 4-8 million existing SAMS patients. Our findings 
have the promise of improving the care of patients with SAMS, allowing them to benefit from 
life-long lipid lowering therapy and reduced cardiovascular risk. 
 
1.e Are novel approaches, methodologies, tools or technologies being used?  
We will use a state-of-the art 7 Tesla MRS Instrument to study the effects of 
statins on mitochondrial function. Three prior studies utilizing MRS to study the effects of 
statins have been published (25-27).  None were done in the past five years, and none with a 
7T field. Their results were varied, likely due to limitations with lower field MRS instruments 
such as reproducibility and long scan times (28).  
The UT Southwestern Advanced Imaging Research Center (AIRC) has one of the few 
available 7T MRS instruments. Compared to 1.5T and 3T, 7T offers much higher detection 
sensitivity and increased spectral resolution (29-34). Patients’ scan times are short and the 
data quality better. Seven Tesla also helps identify small metabolite changes that otherwise 
are difficult to observe at lower fields. 

Our preliminary data indicates that the 7T MRS technique can measure mitochon-
drial function in SAMS patients. We have performed both resting state and exercise meas-
urements of mitochondrial function in a few SAMS patients. First, we did resting state meas-
urements in 3 SAMS patients and one control patient before and after simvastatin 40 mg daily 
for 1 week. MRS data was captured using a recently developed method to assess ATP synthe-
sis rates at rest (35-37). The results were varied. Next, we did pre-and post-exercise (i.e. toe 
lifts for 2 minutes) measurements in 1 SAMS patients before and after starting simvastatin 40 
mg daily. She developed muscle pain after one week of simvastatin, at which time an MRS 
scan was repeated. MRS results identified several changes, most notably an increase in phos-
phocreatine recovery time  (Figure 2) – indicative of impaired oxidative phosphorylation.    
 
Figure 2: A. Representative series of  31P signals acquired from calf muscle of a 65 yr old female SAMS patient at rest (blue traces) and after 2 min calf-
raise exercise (black traces) prior to taking statin (left) and at one week of simvastatin 40 mg daily (right).  Each 31P spectrum represents a 2 min scan.  
Note that the magnitude of Pi signal was greatly reduced immediately after exercise and gradually recovered to its level at rest during post-exercise mus-
cle relaxation. There is also a significant increase in PME signal after exercise, which is slowly attenuated with muscle relaxation.  B. The full series of 180 
phosphocreatine (PCr) 31P signals acquired from the same patient prior to taking statin (left) and after one week of simvastatin 40 mg daily (right), showing 
the slowed oxidative phosphorylation due to simvastatin. The middle row represents zoomed PCr signals at the peak of 31P signals. Top row represents 
the fitted PCr recoveries (red trace).  Each PCr signal represents a single scan with sequence repetition time of 4 sec. Abbreviations: ATP, adenosine 
triphosphate; PCr phosphocreatine; GPC, glycerophosphocholine; Pi, inorganic phosphate; and PME, phosphomonoester including phosphocholine, 
phosphoethanolamine and sugar phosphates.   
After statin treatment
Before statin treatment
31P signals 
PCr Peaks 
PCr recovery 
After statin treatment
Before statin treatment
A.
B.

 
1.f Methodology, potential problems. 
Overall Design of the Study. This is a double-blind randomized, placebo-controlled 
study of simvastatin 40 mg daily vs placebo in SAMS patients. All enrolled subjects will be re-
cruited from lipid specialty clinics and will undergo a washout of lipid lowering drugs followed 
by simvastatin 40 mg daily or placebo challenge for a maximum of 10 weeks (Figure 3).  Visit 2 
will occur either at 10 weeks after visit 1 or at the time muscle symptoms manifest, whichever 
occurs first.   
This study design is based on the most robust clinical trial of SAMS patients (38). This 
study included a double-blind, placebo-controlled statin rechallenge in SAMS patients. Patients 
were challenged with either statin or placebo for 10 weeks in each arm of the study.  
Choice of Study Drug. We chose simvastatin 40 mg daily since it is drug and dose 
most associated with SAMS (2). From each blood draw, we will measure serum levels of 
simvastatin (lactone and acid) as described previously (16). 
Endpoints and Sample Size.  The primary endpoint will be the differences in pre- and 
post-phosphocreatine relaxation time in SAMS patients on simvastatin compared to placebo. 
We chose 15 patients/arm since this sample size is within the range of prior pilot and feasibility 
studies (39).   
Patient Recruitment.  Table 1 outlines inclusion and exclusion criteria for SAMS pa-
tients. We will recruit from existing cohorts (40, 41), and we continue get new SAMS consults 
in our lipid specialty clinics. We expect to be able to recruit 1 SAMS patents and 1 control per 
month. Patients will get $100 per MRS study and $250 per muscle biopsy. 
 
 
 
 
 
 
 
 
Figure 3: Study design 

 
Table 1. Inclusion and exclusion criteria for SAMS patients 
Inclusion Criteria 
Exclusion Criteria 
Adults, age  > 18 ys or < 80 yrs 
Patient who drink large quantities of grapefruit juice (> 1 quart daily). 
Patients reporting complaints of 
statin-associated muscle symp-
toms, aches, weakness, 
cramps, or stiffness in the legs.  
Patients on the following drugs for which the FDA has issued restrictions for using simvastatin 40 mg daily do to an increased risk of 
severe muscle injury such as itraconazole, posaconazole, ketoconazole, erythromycin, clarithromycin, telithromycin, HIV-1 protease 
inhibitors, nefazodone, gemfibrozil, cyclosporine, danazol, amiodarone, amlodipine, ranolazine, and verapamil.  
Patients with muscle-related pain that is not related to statin-use (e.g. muscle aches from strain or trauma) or remains unexplained. 
  Any patients with underlying non-statin related muscle disorders. 
  Presence of any clinically significant uncontrolled endocrine disease known to influence serum lipids or lipoproteins.  
  Conditions of severe acute vascular stress (acute coronary syndrome, ischemic stroke, or major vascular surgery) within prior 3 months. 
  Any patients with a history of severe or life-threatening reactions to statins including rhabdomyolysis (defined as evidence of organ dam-
age with CK >10,000 IU/L), CK elevation > 10 times the upper limit of normal, cognitive decline, transaminitis, or allergic reactions. 
  History of fibromyalgia or rheumatologic disease with symptoms that may be confounded with statin-related muscle complaints. 
  Patients unable to maintain their current activity level or planning to increase their activity level (e.g. new exercise regimen). Such 
changes may have acute effects on muscle metabolism. 
  Pregnant or breast-feeding women. Statins are teratogenic, and the effects of high magnetic fields on a fetus are unknown. 
  Women of reproductive age not on effective contraception. Adequate contraceptive measures include intrauterine device (IUD); bilateral 
tubal ligation; condom or diaphragm plus either contraceptive sponge, foam or jelly. 
  Any person with implanted metal, because of MRS safety.   
  Use of any active investigational drugs within 1 month or 5 half-lives, whichever is longer. 
  History of antibodies to HMGCoA. 
 
MRS Protocol.  The MRS protocol has been previously described (35, 36). MR spectra 
will be measured in the 7T MRI scanner (Achieva, Philips Healthcare, Cleveland, OH).  
For in-magnet exercise to elicit depletion of phosphocreatine (PCr) from calf muscle, the 
subject will be positioned supine and feet-first with the thickest part of the calf positioned in the 
center of the detection coil and secured by Velcro and a thick cushion pad. The ball of the ex-
ercising foot will be in natural contact to the MRI-compatible sand bags which will be fixed on a 
supporting board attached to MRI bed. The sand bags will provide a resistance to the force ex-
erted by the exercising foot.   
The subject will be asked to do exercise after a 2-min baseline 31P MRS scan (TR 4 
sec ), the exercise will be performed for 90 sec with plantar flexion at a frequency of 4 second 
by repetitively pushing on and  releasing from the sand bags. The pushing duration will be 3 
seconds and the releasing 1 second. The subject will be instructed to use maximal force when 
pushing.  After the 90-sec exercise, the subject will be asked to relax but stay still while the 
scan continues. The post-exercise scan will last for 15 min.  
The total scan session, including coil setup, subject preparation/positioning, 31P MRS 
data acquisition, and subject release from the scanner room, will be ~45 min. If a second bout 
of exercise is conducted, the scan session will be ~ 1 hr. 
Muscle Biopsy Specimens.  As described previously (42), muscle tissue will be ob-
tained from the quadriceps muscles, specifically the Vastus lateralis, using the percutaneous 
needle biopsy technique. The average yield should be 150 +/- 20 mg. Specimens will be di-
vided as follows: 50 mg will be required to isolate mitochondria and measure oxygen consump-
tion rates (OCRs), 20 mg for electron microscopy studies, and 15 mg for RNAseq studies. The 
remainder of the sample will be flash frozen at -80°C for potential future studies.  
We will isolate mitochondria from fresh muscle biopsy specimens as previously de-
scribed (42). Muscle homogenates containing equivalent amounts of mitochondria will be dis-
tributed into Seahorse analyzer plates, and OCRs will be measured as described (43) using  a 
Seahorse Xfe96 instrument (Seahorse Bioscience, Billerica, MA, USA). Transmission electron 
microscopy will be done by the UT Southwestern Electron Microscopy Core Facility as de-
scribed previously (44). Gene expression studies will be done and analyzed by the UT South-
western McDermott Center core facilities as previously described (45). 
 
Challenges and Potential Problem Areas and Alternative Tactics. 

Difficulty with recruiting. If this happens we would expand recruitment to other clinics at UT 
Southwestern – such as cardiology and primary care - and affiliated private practices.  
Mitochondrial function not impaired. We will rely on gene expression data to identify pathways 
of interest. 
P MRS data inconclusive. We would turn to 
other data that can be obtained from the stud-
ies: lactate dynamics and or intramyocellular 
lipids as measured by 1H MRS signals. 
 
C3. Timetable – Table 2 
 
2. Significance of Problem to Cardiovascu-
lar or Stroke Research 
2.a How will scientific knowledge or clinical practice be impacted if successful?  
Our contribution here is expected to be an improved understanding of what changes 
occur in muscle mitochondria after SAMS patients take statins. Improved mechanistic insight 
may lead to potential therapeutic interventions targeted at relieving muscle symptoms. 
With respect to outcomes, we expect the MRS studies in this proposal will provide pre-
liminary data to design a larger randomized, double-blind placebo controlled study of simvas-
tatin in SAMS patients. Such a study will validate this technique as a diagnostic tool for SAMS.  
 
2. b Will there be an impact on the methods/concepts/technologies? 
We will improve future studies of SAMS patients. Several prior studies of SAMS patients 
involve statin rechallenges, but these studies have not improved understanding of SAMS (38, 
46, 47). One major issue limits their interpretation: none included any objective measure of 
SAMS, relying instead on self-reported symptoms. The work proposed here will lead to im-
proved clinical trial design. Specifically, this work will lead to objective markers (e.g. MRS sig-
nals) that can be used to select appropriate patients and follow their response to therapy. 
Table 2. TIMETABLE 
AIMS/TASKS 
Month  
1-6 
Month  
6-12 
Month 
12-18 
Month 
18-24 
Patient  Recruitment 
X 
X 
X 
 
MRS Studies 
X 
X 
X 
 
OCRs 
X 
X 
X 
 
Electron  Microscopy 
X 
X 
X 
 
Gene Expression 
 
 
 
X 
Data analysis 
 
 
 
X 
Manuscript Preparation 
 
 
 
X 

 
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