Clinico-serologic features of statin-induced necrotising autoimmune myopathy in a single-centre cohort

Anti-HMGCR (Hydroxy-3-Methylglutaryl-CoA Reductase) Myopathy: A Rare Cause of Proximal Muscle Weakness

Idiopathic inflammatory myopathy (IIM) represents a rare group of autoimmune conditions resulting in muscle weakness and includes polymyositis, dermatomyositis, immune-mediated necrotizing myopathy (IMNM), overlap myositis, and inclusion body myositis. Anti-3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) antibody IMNM represents a rare but increasingly recognized subtype of IIM. Here we report a case of a 65-year-old woman on rosuvastatin who presented with two months of progressive proximal muscle weakness, significant truncal weakness, and elevated creatine kinase concerning for rhabdomyolysis and inflammatory myopathy. The patient was eventually diagnosed on day 8 of her hospital stay with anti-HMGCR antibody IMNM after delayed testing for this specific myopathy. Increased awareness of this IIM subtype, as well as its risk factors and presenting features, might improve rapidity of testing and shorten hospital stays if the diagnosis is considered in the emergency department or early in the hospital course.

Anti-HMGCR immune-mediated necrotising myopathy: Addressing the remaining issues

The discovery of autoantibodies directed against the 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) enzyme has defined a sub-set of immune-mediated necrotising myopathy (IMNM) which is strongly associated with exposure to statin medications. Although understanding of anti-HMGCR IMNM has grown considerably with the reporting of multiple cohorts in North America, Europe, Asia and Oceania, there remain many unanswered questions. The true incidence of anti-HMGCR IMNM is not known and heterogeneity of phenotype and treatment response within this autoantibody sub-group is being increasingly recognised. Statin-naïve adults and juvenile patients with anti-HMGCR potentially share characteristics distinct from statin-exposed patients, alluding to unique pathogenesis. Conflicting data exists on whether malignancies are associated with anti-HMGCR and further clarification is required to determine the degree of cancer screening required. Treatment approaches to anti-HMGCR IMNM are heterogeneous but generally highlight the efficacy of intravenous immunoglobulin. Even with multimodal immunosuppression, patients with anti-HMGCR remain prone to relapse, with younger patients generally manifesting more refractory disease. In this Review, we aim to summarise the current literature on anti-HMGCR and discuss the remaining issues.

Clinicopathological and circulating cell-free DNA profile in myositis associated with anti-mitochondrial antibody

OBJECTIVE

Anti-mitochondrial antibodies (AMAs) are associated with idiopathic inflammatory myopathies (IIMs). We aimed to summarize the clinicopathological characteristics, assess circulating cell-free mitochondrial DNA (ccf-mtDNA), and circulating cell-free nuclear DNA (ccf-nDNA) in AMA-associated IIMs.

METHODS

Medical records of 37 IIMs patients with AMAs were reviewed. Circulating cell-free mtDNA and ccf-nDNA levels in sera from IIMs patients with AMAs (n = 21), disease controls (n = 66) and healthy controls (HCs) (n = 23) were measured and compared. Twenty-eight immune-mediated necrotizing myopathy (IMNM) patients, 23 dermatomyositis (DM) patients, and 15 anti-synthetase syndrome (ASS) patients were enrolled as disease controls. Correlations between variables were analyzed.

RESULTS

Limb weakness was observed in 75.7% and neck weakness in 56.8% of patients. Cardiac involvement occurred in 51.4% of patients. Muscle pathology revealed 81.1% of IMNM, 5.4% polymyositis, and 13.5% nonspecific myositis. Microinfarction was observed in 8.1% of patients. Serum ccf-mtDNA levels in AMA-associated IIMs were significantly higher than those in HCs (p < 0.001), but no significant differences between AMA-associated IIMs and IMNM, DM, or ASS. Serum ccf-nDNA levels in AMA-associated IIMs were significantly higher than those in HCs (p = 0.02), and significantly lower than those in DM (p = 0.02). Serum ccf-nDNA levels correlated negatively with MMT8 total scores (rs = -0.458, p = 0.037) and positively with mRS scores (rs = 0.486, p = 0.025). Serum ccf-nDNA levels were significantly higher in the non-remission group (p < 0.01).

INTERPRETATION

AMA-associated IIMs exhibit distinct clinicopathological features. Serum ccf-nDNA may serve as a potential marker for disease severity and prognosis in AMA-associated IIMs.

Clinical associations of patients with anti-3-hydroxy-3-methylglutaryl CoA reductase antibody-associated immune-mediated necrotising myopathy

BACKGROUND

Anti-3-hydroxy-3-methylglutaryl CoA reductase (HMGCR) antibodies are associated with a subtype of immune-mediated necrotising myopathy (IMNM).

AIMS

To determine clinical associations of anti-HMGCR antibodies for anti-HMGCR-associated IMNM (HMGCR-IMNM) among a cohort of patients in Western Australia and to determine whether serial HMGCR antibody levels parallel disease activity.

METHODS

Adult patients with positive anti-HMGCR antibodies detected by enzyme-linked immunosorbent assay between January 2015 and November 2019 were included. Symptoms, examination findings, imaging findings and blood test results were reviewed retrospectively using patient records and laboratory database results.

RESULTS

Among 26 patients with positive anti-HMGCR antibodies, 23 were diagnosed with HMGCR-IMNM representing a positive predictive value (PPV) of 88%. Myopathy was frequently severe at diagnosis with limb weakness graded as Medical Research Council score 3 or below in 78% of patients, bulbar muscle weakness in 39% and an average creatine kinase (CK) at diagnosis of 7986 U/L. The majority (83%) required at least two therapies to maintain remission, 48% had at least one flare of disease and 57% did not achieve CK normalisation. Correlation between CK and anti-HMGCR antibody level at diagnosis was low (r = 0.04). Anti-HMGCR antibodies fell with treatment in 10 of 12 patients, but remained persistently positive in 83% of patients.

CONCLUSIONS

The PPV of anti-HMGCR antibodies for HMGCR-IMNM in this Western Australian cohort is 88%. Patients typically present with proximal limb weakness, dysphagia and markedly elevated CK, and, despite multiagent immunosuppression, a significant number of patients have evidence of persistent biochemical myositis. Anti-HMGCR antibodies did not correlate with CK levels at diagnosis.

A Child with Refractory and Relapsing Anti-3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase Myopathy: Case-Based Review

BACKGROUND/OBJECTIVE

Anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (anti-HMGCR) myopathy is rare in children. Here, we present a boy with relapsing refractory anti-HMGCR myopathy along with a systematic literature review.

CASE REPORT

17-year-old boy with five years of muscle weakness, rash, high creatinine kinase (CK) levels, and muscle biopsy compatible with inflammatory myopathy was diagnosed with juvenile dermatomyositis. He was treated with corticosteroids, intravenous immunoglobulin (IVIG), and methotrexate. His muscle weakness improved with this treatment although never completely resolved. CK levels decreased from ∼15000 U/L to ∼3000 U/L. At the age of 15, muscle weakness relapsed after an upper respiratory tract infection; pulse corticosteroid treatment was administered. The re-evaluated muscle biopsy showed a necrotizing pattern and the HMGCR antibody was positive confirming anti-HMGCR myopathy when he was 16. The diagnostic delay was 50 months. Disease activity was monitored by Medical Research Council score, MRI and functional tests. Despite corticosteroids, methotrexate, IVIG, cyclosporine A, and rituximab therapies, muscle weakness improved only slightly during the first three months and remained stable afterwards.Results of the Literature Search:We identified 16 articles describing 50 children (76% female) with anti-HMGCR myopathy by reviewing the English literature up to March 1st, 2022. Proximal muscle weakness was the most common clinical symptom (70.8%). Corticosteroids (84.8%), IVIG (58.7%), and methotrexate (56.5%) were preferred in most cases. Complete remission was achieved in nine patients (28.1%).

CONCLUSION

Diagnosis and management of children with anti-HMGCR myopathy are challenging. Complete remission is achieved in only one third of these patients. Imaging biomarkers may aid treatment.

Epidemiological and genetic features of anti-3‑hydroxy-3-methylglutaryl-CoA reductase necrotizing myopathy: Single-center experience and literature review

OBJECTIVE

To characterize the demographic, genetic, clinical, and serological features of patients with anti-3‑hydroxy-3-methylglutaryl-CoA reductase (HMGCR) immune-mediated necrotizing myopathy (IMNM) in a region of northern Spain.

METHODS

Study of all patients diagnosed with anti-HMGCR IMNM during a 5-year period at a reference hospital in northern Spain. Besides clinical and laboratory data, we analyzed the genetic influence of HLA genes and the rs4149056 (c.521T>C) single nucleotide polymorphism (SNP) in the SLCO1B1 gene.

RESULTS

8 patients (5 women, 3 men) with a mean ± SD age of 64.9 ± 7.3 years, fulfilled the criteria for anti-HMGCR IMNM. The incidence rate was 0.6 per 100.000 person-years and the prevalence 3 per 100.000 population. All patients had been exposed to statins. All of them had predominant lower limb proximal and symmetric muscle weakness that was severe in 2 and had elevated serum CK levels with a median [IQR] of 4488 [2538-9194] IU/L. Serum 25‑hydroxy vitamin D levels were decreased in all patients in whom it was determined. The 3 patients with a previous diagnosis of hypothyroidism had abnormal levels of TSH at the time of diagnosis. All patients experienced improvement with different schemes of immunosuppressive therapy. Noteworthy, 7 of 8 patients carried the HLA-DRB1*11 allele. The frequency of the rs4149056 C allele in the SLCO1B1 gene (12.5%) was similar to that of the general population.

CONCLUSION

In northern Spain, anti-HMGCR IMNM preferentially affects people over 50 years of age who are carriers of the HLA-DRB1*11 allele and take statins. Both low vitamin D levels and hypothyroidism may play a potential predisposing role in the development of this disease.

The prevalence and clinical characteristics of anti-HMGCR (anti-3-hydroxy-3-methyl-glutaryl-coenzyme A reductase) antibodies in idiopathic inflammatory myopathy: an analysis from the MyoCite registry

This study aimed to determine the prevalence and clinical characteristics of anti-HMGCR antibodies in idiopathic inflammatory myositis (IIM) at a tertiary care centre in northern India. Data (adult and children) were retrieved from the MyoCite dataset, identifying patients with polymyositis, dermatomyositis, and antibody-negative IIM whilst fulfilling the ACR/EULAR criteria. SLE, sarcoidosis, and systemic sclerosis were included for comparison as disease controls. The baseline clinical profile, laboratory tests, and muscle biopsies were retrieved and analysed. Descriptive statistics and non-parametric statistics were used for comparison. Among 128 IIM (112 adults, 16 children, M:F 1:2.8) of age 37 (24-47) years and 6 (3-17) months disease duration, 4 (3.6%) young adults tested positive for anti-HMGCR antibodies. All children and disease control tested negative for the antibody. Anti-HMGCR + IIM exhibited higher muscle enzymes [AST (367 vs 104 IU/L, p = 0.045), ALT (502 vs 78 IU/L, p = 0.004), and CPK (12,242 vs 699 IU/L, p = 0.001] except lactate dehydrogenase with less frequent systemic features such as fatigue than antibody-negative IIM. One young girl presented with a Limb-girdle muscular dystrophy (LGMD) with chronic pattern. None of the patients exhibited rashes, statin exposure, or cancer, though one had anti-Ro52 and mild disease. Our observations depict a younger population while affirming previous literature, including NM-like presentation, and chronic LGMD-like pattern of weakness in one case. Although a small number of children were included, ours is one of the few paediatric studies that evaluated HMGCR antibodies thus far. Further investigations in a larger Indian cohort are warranted to substantiate our findings.

Statin-Associated Autoimmune Myopathy: Review of the Literature

OBJECTIVE

Statin-associated autoimmune myopathy (SAAM) is a rare adverse event characterized by progressive muscle symptoms despite discontinuation, requiring immunosuppressive therapy for remission. The objective of this review was to characterize SAAM, for timely detection, while examining the literature for effective treatment considerations.

METHODS

PubMed search was conducted from 2010 to 2020 was for relevant case series and studies of at least 8 patients displaying muscle discomfort or weakness, anti-HMGCR antibodies, exposure to statins, and biopsies consistent with SAAM.

RESULTS

Three case series and 3 case cohort studies identified 199 patients with SAAM. Exhibiting a mean age of 63.74 years, patients were more likely Caucasian (81%) and female (1.2X), and required a mean duration of 4.75 years before symptomatic. The presentation involved proximal muscle weakness (94%), myalgias (37%) and dysphagia (23%), accompanied by a mean creatinine kinase of 6383 IU/L. Most patients (57%) required 2 or more immunosuppressive (IMS) agents to achieve 62% remission. After 2 years of treatment, 15% of patients without remission reported symptomatic improvement, while another 12% were refractory to treatment.

CONCLUSION

Delayed onset of SAAM greater than 4 years from statin initiation may create a low index of suspicion. However, progression of symptoms beyond 2 months from statin discontinuation and positive anti-HMGCR antibodies requires immunosuppressive agents. Data and expert opinion support use of at least two IMS medications upon diagnosis for a minimum of 2 years. Therapy success depends on timely recognition and initiation of IMS combinations to achieve earlier remission and symptomatic improvement.

[Rhabdomyolysis with tetraparesis secondary to hepatitis E virus infection in a patient on statins]

INTRODUCTION

Neurologic and muscular damage associated with acute hepatitis due to hepatitis E virus (HEV) are rare and may be underdiagnosed.

CASE REPORT

We report the case of a 56-year-old man, presenting with flaccid tetraparesis secondary to an acute rhabdomyolysis induced by acute E virus hepatitis. He fully recovered after one month under supportive treatment.

DISCUSSION

Rare cases of acute rhabdomyolysis induced by HEV infection have been reported in the literature. We discuss the potential adjuvant role of statin treatment in our patient. Unexplained acute neurological conditions should prompt the search for HEV infection.

Anti-HMGCR myopathy: clinical and histopathological features, and prognosis

PURPOSE OF REVIEW

This review aims to describe clinical and pathological features, prognosis and treatment in patients with anti-HMGCR antibody positive immune-mediated necrotizing myopathy (HMGCR-IMNM) based on recent findings.

RECENT FINDINGS

Using advances in diagnostic modalities that can confirm the presence of anti-HMGCR antibody, the clinical and pathological manifestations of HMGCR-IMNM were found to be broader than previously reported. Although only a small percentage of HMGCR-IMNM patients present with atypical manifestations, some of these patients show slow disease progression and clinical symptoms, which are similar to those of limb-girdle muscular dystrophies. Other atypical HMGCR-IMNM patients have skin conditions similar to dermatomyositis-like skin rush or dermatological presentations of Jessner-Kanoff disease or cutaneous lymphoma, whose pathological changes including CD8-positive and bcl-2-positive lymphocytic accumulations, similar to Jessner-Kanoff lymphocytic infiltration of skin or low-grade cutaneous lymphoma, which are observed in muscle and skin.

SUMMARY

Anti-HMGCR autoantibodies define unique populations of IMNM patients. Recent studies have revealed that clinicopathological manifestations of HMGCR-IMNM, especially extramuscular symptoms and pathological manifestations, are more common than previously recognized.

Statin use and myopathy. Not always guilty

OBJECTIVES

Statins are the cornerstone of the treatment and prevention of cardiovascular disease but have been associated with muscular side effects, among others. If patients are not properly evaluated, statin discontinuation may take place, leaving patients' symptoms unresolved and precluding an effective cardiovascular treatment. The present study aims to describe the clinical characteristics, the diagnostic process and the final diagnosis of selected patients with suspected statin-induced myopathy, with quite different alternative diagnoses.

METHODS

Among the 86 patients referred to our unit for evaluation since 2012, 6 patients with suspected statin-induced myopathy that was finally ruled out were selected as examples because of their illustrative value. All patients were evaluated in a Muscular Diseases Unit by myology experts, and additional testing was performed according to clinical suspicion.

RESULTS

Of the six selected patients with suspected statin-induced myopathy, three had a neurogenic aetiology, two had vacuolar myopathies and one had severe hypothyroidism. Statins were permanently discontinued in two cases, with the treatment of one of the latter patients being continued with a protein convertase subtilisin/kexin type 9 (PCSK9) inhibitor.

CONCLUSION

Not all patients taking statins who develop muscle complaints have statin-related myopathy. A thorough clinical evaluation and appropriate testing is warranted to avoid an unnecessary increase in cardiovascular risk.

Efficacy and Safety of High-Dose Immunoglobulin-Based Regimen in Statin-Associated Autoimmune Myopathy: A Multi-Center and Multi-Disciplinary Retrospective Study

Statin-associated autoimmune myopathy is a rare muscle disorder, characterized by autoantibodies against HMGCR. The anti-HMGCR myopathy persists after statin, and often requires immunosuppressive therapy. However, there is not a standardized therapeutic approach. The purpose of this study is to report the effectiveness of the immunosuppressive treatment employed in a multi-center and multi-disciplinary cohort of patients affected by anti-HMGCR myopathy, in which an immunoglobulin (IVIG)-based treatment strategy was applied. We collected 16 consecutive patients with a diagnosis of anti-HMGCR myopathy, between 2012 and 2019, and recorded data on clinical and laboratory presentation (i.e., muscle strength, serum CK levels, and anti-HMGCR antibody titer) and treatment strategies. Our results highlight the safety and efficacy of an induction therapy combining IVIG with GCs and/or methotrexate to achieve persistent remission of the disease and steroid-free maintenance. Under IVIG-based regimens, clinical improvement and CK normalization occurred in more than two thirds of patients by six months. Relapse rate was low (3/16) and 2/3 relapses occurred after treatment suspension. Nearly 90% of the patients who successfully discontinued GCs were treated with a triple immunosuppressive regimen. In conclusion, an IVIG-based regimen, which particularly includes high-dose immunoglobulin, GCs and methotrexate, can provide a fast remission achievement with GC saving.

Treatment experience of Taiwanese patients with anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase myopathy

Immune-mediated necrotizing myopathy (IMNM) has emerged as a new subgroup of idiopathic inflammatory myopathy in the past decade, associated with the presence of two autoantibodies against signal recognition particle and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR). We aim to analyze the clinical, pathological, and imaging phenotypes of the patients with anti-HMGCR myopathy in our cohort. Five patients with anti-HMGCR myopathy have been enrolled who were all female; three were pediatric and two were adult patients. The muscle pathology of patients met the diagnostic criteria of IMNM. On muscle magnetic resonance imaging, adductors were earliest affected while lower legs were relatively preserved with highest degree of involvement in medial head of gastrocnemius. In upper extremities, biceps brachii was the most severely involved, followed by triceps. All patients were refractory to steroid mono-therapy. For pediatric patients, all three patients eventually became responsive to steroid with either intravenous immunoglobulin or rituximab despite variable motor function recovered at present due to different intervention timing. For adult patients, one with statin exposure responded well to steroid and azathioprine use and the motor function returned to the baseline. The other adult patient finally got stabilized and slowly improved with steroid and methotrexate 13 years after the start of therapy. The creatine kinase (CK) levels of all patients were decreased along with clinical severity. In conclusion, muscle imaging might be of help for the diagnosis. Treatment with immuno-suppressants could be considered together with steroid from the beginning.

Favorable Response in Statin-Naive Paraneoplastic Anti-HMGCR Antibody-Associated Myopathy to Single Dose of Rituximab and Persistent Remission With Management of Underlying Lung Cancer

Anti-HMGCR myopathy is a subtype of immune-mediated necrotizing myopathy, typically associated with exposure to statins, although a sizable minority in some cohorts are statin-naive. Although the clinical features of acute- or subacute-onset symmetrical proximal muscle weakness mimic those of other idiopathic inflammatory myopathies, necrotizing myopathy is distinguished by the histopathological findings of muscle fiber necrosis and regeneration with little to no accompanying inflammation. Several recent studies of patients with anti-HMGCR myopathy have identified a slightly increased risk of cancer. Most patients require aggressive immunotherapy, usually as a combination of 2 or 3 immunosuppressant drugs. We report a case of a statin-naive paraneoplastic anti-HMGCR myopathy, who unlike other reported cases, responded to a single dose of 1000 mg of intravenous rituximab and subsequent chemoradiation therapy for an underlying lung cancer, despite failing to completely respond to prior high-dose oral prednisone and methotrexate.

Statin-Associated Autoimmune Myopathy: Current Perspectives

Although generally well tolerated, statin users frequently report muscle-related side effects, ranging from self-limiting myalgias to rhabdomyolysis or the rare clinical entity of statin-associated immune-mediated necrotizing myopathy (IMNM). Statin-associated IMNM is based on the development of autoantibodies against 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), the rate-limiting enzyme in cholesterol synthesis and the pharmacologic target of statins, and leads to a necrotizing myopathy requiring immunosuppressive therapy. This review attempts to recapitulate the diverse aspects of anti-HMGCR IMNM, including clinical presentation, diagnostic modalities, genetic risk associations, therapeutic options and potential pathogenetic pathways.

An overview of statin-induced myopathy and perspectives for the future

Introduction: Statins remain the most commonly prescribed lipid-lowering drug class for the treatment of atherosclerotic cardiovascular disease. Their well-recognized side effects are known as statin-associated muscle symptom (SAMS). Some advances in this field have been made in recent years, but the understanding of the mechanisms has lagged. Investigating the specific role of the anti-HMGCR autoantibody, pharmacokinetic genetic variants, characterization of the known phenotypes of statin toxicity, in relation to clinical markers of disease, is of high importance.Areas covered: We summarized currently available findings (on PubMed) related to SAMS and discussed the therapeutic approaches, risk factors, drug interactions, potential novel systems, algorithms and biomarkers for SAMS detection. CoQ10 supplementation has been suggested as a complementary approach to manage SAMS, while vitamin D levels may be useful for both the diagnosis and management.Expert Opinion/Commentary: Further studies might help to understand the easiest way to diagnose SAMS, suitable prevention and an effective non-statin therapy. This review sheds new light on the future directions in both research and clinical practice, which will help with rapid risk assessment, identification of the SAMS risk factors in order to decrease the incidence of statins' adverse effects, and the most effective therapy.

Muscle Toxicity of Drugs: When Drugs Turn Physiology into Pathophysiology

Drugs are prescribed to manage or prevent symptoms and diseases, but may sometimes cause unexpected toxicity to muscles. The symptomatology and clinical manifestations of the myotoxic reaction can vary significantly between drugs and between patients on the same drug. This poses a challenge on how to recognize and prevent the occurrence of drug-induced muscle toxicity. The key to appropriate management of myotoxicity is prompt recognition that symptoms of patients may be drug related and to be aware that inter-individual differences in susceptibility to drug-induced toxicity exist. The most prevalent and well-documented drug class with unintended myotoxicity are the statins, but even today new classes of drugs with unintended myotoxicity are being discovered. This review will start off by explaining the principles of drug-induced myotoxicity and the different terminologies used to distinguish between grades of toxicity. The main part of the review will focus on the most important pathogenic mechanisms by which drugs can cause muscle toxicity, which will be exemplified by drugs with high risk of muscle toxicity. This will be done by providing information on key clinical and laboratory aspects, muscle electromyography patterns and biopsy results, and pathological mechanism and management for a specific drug from each pathogenic classification. In addition, rather new classes of drugs with unintended myotoxicity will be highlighted. Furthermore, we will explain why it is so difficult to diagnose drug-induced myotoxicity, and which tests can be used as a diagnostic aid. Lastly, a brief description will be given of how to manage and treat drug-induced myotoxicity.

Disease Specific Autoantibodies in Idiopathic Inflammatory Myopathies

Idiopathic inflammatory myopathies represent still a diagnostic and therapeutic challenge in different disciplines including neurology, rheumatology, and dermatology. In recent years, the spectrum of idiopathic inflammatory myopathies has been significantly extended and the different manifestations were described in more detail leading to new classification criteria. A major breakthrough has also occurred with respect to new biomarkers especially with the characterization of new autoantibody-antigen systems, which can be separated in myositis specific antibodies and myositis associated antibodies. These markers are detectable in approximately 80% of patients and facilitate not only the diagnostic procedures, but provide also important information on stratification of patients with respect to organ involvement, risk of cancer and overall prognosis of disease. Therefore, it is not only of importance to know the significance of these markers and to be familiar with the optimal diagnostic tests, but also with potential limitations in detection. This article focuses mainly on antibodies which are specific for myositis providing an overview on the targeted antigens, the available detection procedures and clinical association. As major tasks for the near future, the need of an international standardization is discussed for detection methods of autoantibodies in idiopathic inflammatory myopathies. Furthermore, additional investigations are required to improve stratification of patients with idiopathic inflammatory myopathies according to their antibody profile with respect to response to different treatment options.

Immune-mediated necrotising myopathy: A critical review of current concepts

Immune-mediated necrotising myopathy (IMNM) is a relatively recently described form of idiopathic inflammatory myopathy (IIM) that is characterised by progressive proximal weakness and few extra-muscular manifestations. Prominent myonecrosis, muscle fibre regeneration and a relative paucity of intramuscular lymphocytes are seen histologically. Immunological mechanisms are believed to underpin the pathogenesis, and intense immunotherapy is frequently required. Disease is often severe and neuromuscular recovery may be poor. Recently there has been an impressive international research effort to understand and characterise this emerging condition, although much remains unknown. Significant advances in the field include the discovery of specific autoantibodies, increased understanding of the risk factors, clinical characteristics and treatment options owing to a wealth of observational studies, and the development of novel classification criteria. Herein we review the current evidence regarding the pathophysiology, clinical presentation, histological features and serological profiles associated with this condition. Diagnostic approaches are discussed, including the role of muscle MRI and antibodies targeting 3‑hydroxy-3-methylglutaryl-CoA reductase (HMGCR) and signal-recognition peptide (SRP), and a review of current treatment recommendations is provided.

Myopathy in a 61-year-old Hispanic man

A 61-year-old Hispanic man presented to a county hospital for subacute progressive weakness, heliotrope rash and dysphagia. There was initial suspicion for dermatomyositis (DM) given the history; however, the physical exam was not consistent. An MRI followed by a muscle biopsy revealed necrotising autoimmune myositis and anti-3-hydroxy-3-methylglutary-coenzyme A-reductase antibody titers returned positive; the patient was diagnosed with necrotising autoimmune myositis. He was treated with corticosteroids and intravenous immunoglobulin, which resulted in improvement in his weakness and functional status. This case represents a unique instance in which a cardinal feature of DM, the heliotrope rash, prompted an erroneous initial diagnosis. It highlights the necessity of developing abroad differential diagnosis and subsequent thorough investigation into patients presenting with suspected idiopathic immune-mediated myopathies.

Formal comment on "Systematic review of the predictors of statin adherence for the primary prevention of cardiovascular disease"

Statins have been prescribed for primary prevention of cardiovascular disease (CVD) for nearly 3 decades. Throughout this period key opinion leaders in the field have been dismayed by the high rate of non-adherence of patients to follow their statin regimen. Hope et al., [1] have addressed this issue by providing a systematic review of research on predictors of statin adherence for primary prevention of CVD. However, their review does not address the ongoing debate as to whether statin treatment is warranted for primary prevention of CVD, nor does it adequately address concerns regarding adverse effects of statins. We have therefore written a commentary which provides a broader perspective on the benefits versus harms of statin therapy. Our perspective of the literature is that non-adherence to statin treatment for primary prevention of CVD is justified because the meager benefits are more than offset by the extensive harms.

Anti-HMGCR myopathy may resemble limb-girdle muscular dystrophy

Objective

To determine the prevalence and clinical features of anti-HMGCR myopathy among patients with presumed limb-girdle muscular dystrophy (LGMD) in whom genetic testing has failed to elucidate causative mutations.

Methods

Patients with presumed LGMD and unrevealing genetic testing were selected based on a few clinico-pathologic features and tested for anti-HMGCR autoantibodies (n = 11). These clinico-pathologic features are peak creatine kinase (CK) greater than 1,000 IU/L and at least 3 of the following features: (1) limb-girdle pattern of weakness, (2) selective involvement of posterior thigh on clinical examination or muscle imaging, (3) dystrophic changes on muscle biopsy, and (4) no family history of muscular dystrophy.

Results

Six patients tested positive for anti-HMGCR autoantibodies. In 4, there was a presymptomatic phase, lasting as long as 10 years, characterized by elevated CK levels without weakness. Muscle biopsies revealed variable degrees of a dystrophic pathology without prominent inflammation. In an independent cohort of patients with anti-HMGCR myopathy, 17 of 51 (∼33%) patients were initially presumed to have a form of LGMD based on clinico-pathologic features but were ultimately found to have anti-HMGCR myopathy. Most of these patients responded favorably to immunomodulatory therapies, evidenced by reduction of CK levels and improved strength.

Conclusions

Anti-HMGCR myopathy can resemble LGMD. Diagnosis of patients with a LGMD-like presentation of anti-HMGCR myopathy is critical because these patients may respond favorably to immunotherapy, especially those with shorter disease duration.

Anti-HMGCR Myopathy

Anti-HMGCR myopathy was first recognized and characterized in patients with a history of statin exposure and immune-mediated necrotizing myopathy. After the discovery of anti-HMGCR autoantibodies, several international groups identified and characterized more patients, expanding the phenotypic spectrum of this disease to include pediatric patients and young adults without statin exposure and those with a chronic myopathy resembling limb-girdle muscular dystrophy. We provide a summary of clinical findings, pathologic features, muscle imaging, and immunogenetic risk factors of the disease. We also discuss the current treatment strategies and approaches to monitoring the therapeutic response. Lastly, we briefly summarize the current understanding of the pathophysiology of the disease and postulate a model for autoimmunity initiation and propagation in this disease.