Importance of three-dimensional speckle tracking in the assessment of left atrial and ventricular dysfunction in patients with myotonic dystrophy type 1

Echocardiographic Features of Cardiac Involvement in Myotonic Dystrophy 1: Prevalence and Prognostic Value

Myotonic dystrophy type 1 (DM1) is the most common muscular dystrophy in adults. Cardiac involvement is reported in 80% of cases and includes conduction disturbances, arrhythmias, subclinical diastolic and systolic dysfunction in the early stage of the disease; in contrast, severe ventricular systolic dysfunction occurs in the late stage of the disease. Echocardiography is recommended at the time of diagnosis with periodic revaluation in DM1 patients, regardless of the presence or absence of symptoms. Data regarding the echocardiographic findings in DM1 patients are few and conflicting. This narrative review aimed to describe the echocardiographic features of DM1 patients and their prognostic role as predictors of cardiac arrhythmias and sudden death.

Normative healthy reference values for global and segmental 3D principal and geometry dependent strain from cine cardiac magnetic resonance imaging

3-Dimensional (3D) myocardial deformation analysis (3D-MDA) enables novel descriptions of geometry-independent principal strain (PS). Applied to routine 2D cine cardiovascular magnetic resonance (CMR), this provides unique measures of myocardial biomechanics for disease diagnosis and prognostication. However, healthy reference values remain undefined. This study describes age- and sex-stratified reference values from CMR-based 3D-MDA, including 3D PS. One hundred healthy volunteers were prospectively recruited following institutional ethics approval and underwent CMR imaging. 3D-MDA was performed using validated software. Age- and sex-stratified global and segmental strain measures were derived for conventional geometry-dependent [circumferential (CS), longitudinal (LS), and radial (RS)] and geometry-independent [minimum (minPS) and maximum principal (maxPS)] directions of deformation. Layer-specific contraction angle interactions were determined using local minPS vectors. The average age was 43 ± 15 years and 55% were women. Strain measures were higher in women versus men. 3D PS-based assessment of maximum tissue shortening (minPS) and maximum tissue thickening (maxPS) were greater than corresponding geometry-dependent markers of LS and RS, consistent with improved representation of local tissue deformations. Global maxPS amplitude best discriminated both age and sex. Segmental analyses showed greater strain amplitudes in apical segments. Transmural PS contraction angles were higher in females and showed a heterogeneous distribution across segments. In this study we provided age and sex-based reference values for 3D strain from CMR imaging, demonstrating improved capacity for 3D PS to document maximal local tissue deformations and to discriminate age and sex phenotypes. Novel markers of layer-specific strain angles from 3D PS were also described.

Myotonic dystrophy type 1 presenting with dyspnea: A case report

BACKGROUND

Myotonic dystrophy type 1 (DM1) is a genetic neuromuscular disease involving multiple systems, especially the cardiopulmonary system. The clinical phenotype of DM1 patients is highly variable, which limits early diagnosis and treatment. In the present study, we reported a 35-year-old female DM1 patient with dyspnea as the primary onset clinical manifestation, analyzed her family's medical history, and reviewed related literature.

CASE SUMMARY

A 35-year-old woman was admitted to the hospital with dyspnea of 1 mo duration, and sleep apnea for 3 d. Her respiratory pattern and effort were normal, but limb muscle tension was low. Investigation into the patient's medical history revealed that she might have hereditary neuromuscular disease. Electromyography showed that her myotonia potentials were visible in the resting state of the examined muscles, with decreased motor unit potential time limit and amplitude. Genetic testing for DM1 revealed that the cytosine-thymine-guanine (CTG) repeat number of the DMPK gene exceeded 50, while cytosine-CTG expansion in intron 1 of ZNF9 gene was < 30 repeats. The patient was diagnosed with DM1.

CONCLUSION

DM1 is a genetic neuromuscular disease involving multiple systems, and the clinical phenotype in DM1 is extremely variable. Some patients with DM1 may be presented at the respiratory department because of dyspnea, which should be cautioned by the pulmonologists. There may be no obvious or specific symptoms in the early stage of disease, and clinicians should improve their understanding of DM1 and make an early diagnosis, which will improve patients’ quality of life.

Outcome measures frequently used to assess muscle strength in patients with myotonic dystrophy type 1: a systematic review

Measurement of muscle strength is fundamental for the management of patients with myotonic dystrophy type 1 (DM1). Nevertheless, guidance on this topic is somewhat limited due to heterogeneous outcome measures used. This systematic literature review aimed to summarize the most frequent outcome measures to assess muscle strength in patients with DM1. We searched on Pubmed, Web of Science and Embase databases. Observational studies using measures of muscle strength assessment in adult patients with DM1 were included. From a total of 80 included studies, 24 measured cardiac, 45 skeletal and 23 respiratory muscle strength. The most common method and outcome measures used to assess cardiac muscle strength were echocardiography and ejection fraction, for skeletal muscle strength were quantitative muscle test, manual muscle test and maximum isometric torque and medical research council and for respiratory muscle strength were manometry and maximal inspiratory and expiratory pressure. We successfully gathered the more consensual methods and measures to evaluate muscle strength in future clinical studies, particularly to test muscle strength response to treatments in patients with DM1. Future consensus on a set of measures to evaluate muscle strength (core outcome set), is important for these patients.

Metabolic Alterations in Myotonic Dystrophy Type 1 and Their Correlation with Lipin

Myotonic dystrophy type 1 (DM1) is an autosomal dominant hereditary and multisystemic disease, characterized by progressive distal muscle weakness and myotonia. Despite huge efforts, the pathophysiological mechanisms underlying DM1 remain elusive. In this review, the metabolic alterations observed in patients with DM1 and their connection with lipin proteins are discussed. We start by briefly describing the epidemiology, the physiopathological and systemic features of DM1. The molecular mechanisms proposed for DM1 are explored and summarized. An overview of metabolic syndrome, dyslipidemia, and the summary of metabolic alterations observed in patients with DM1 are presented. Patients with DM1 present clinical evidence of metabolic alterations, namely increased levels of triacylglycerol and low-density lipoprotein, increased insulin and glucose levels, increased abdominal obesity, and low levels of high-density lipoprotein. These metabolic alterations may be associated with lipins, which are phosphatidate phosphatase enzymes that regulates the triacylglycerol levels, phospholipids, lipid signaling pathways, and are transcriptional co-activators. Furthermore, lipins are also important for autophagy, inflammasome activation and lipoproteins synthesis. We demonstrate the association of lipin with the metabolic alterations in patients with DM1, which supports further clinical studies and a proper exploration of lipin proteins as therapeutic targets for metabolic syndrome, which is important for controlling many diseases including DM1.

Three-dimensional speckle-tracking echocardiography for evaluating myocardial motion in patients with cardiorenal syndrome

Because of better awareness and understanding of its pathophysiology, the cardiorenal syndrome (CRS) is more often diagnosed and better managed. The echocardiographic evaluation of CRS now benefits from three-dimensional speckle tracking echocardiography (3D-STE), which allows multidimensional and real-time evaluation of regional myocardial and overall cardiac function, and helps assessing the degree of myocardial damage. This article describes the application of 3D-STE in evaluating the myocardial motion in patients with CRS.