Evaluation of biventricular functions with tissue Doppler imaging in patients with myotonic dystrophy

Cardiac magnetic resonance findings and prognosis in type 1 myotonic dystrophy

BACKGROUND

Cardiac involvement is a major determinant of prognosis in type 1 myotonic dystrophy (DM1), but limited information is available about myocardial remodeling and tissue changes. The aim of the study was to investigate cardiac magnetic resonance (CMR) findings and their prognostic significance in DM1.

METHODS

We retrospectively identified all DM1 patients referred from a neurology unit to our CMR laboratory from 2009 to 2020.

RESULTS

Thirty-four patients were included (aged 45 ± 12, 62% male individuals) and compared with 68 age-matched and gender-matched healthy volunteers (43 male individuals, age 48 ± 15 years). At CMR, biventricular and biatrial volumes were significantly smaller (all P < 0.05), as was left ventricular mass (P < 0.001); left ventricular ejection fraction (LVEF) and right ventricular ejection fraction (RVEF) were significantly lower (all P < 0.01). Five (15%) patients had a LVEF less than 50% and four (12%) a RVEF less than 50%. Nine patients (26%) showed mid-wall late gadolinium enhancement (LGE; 5 ± 2% of LVM), and 14 (41%) fatty infiltration. Native T1 in the interventricular septum (1041 ± 53 ms) was higher than for healthy controls (1017 ± 28 ms) and approached the upper reference limit (1089 ms); the extracellular volume was slightly increased (33 ± 2%, reference <30%). Over 3.7 years (2.0-5.0), 6 (18%) patients died of extracardiac causes, 5 (15%) underwent device implantation; 5 of 21 (24%) developed repetitive ventricular ectopic beats (VEBs) on Holter monitoring. LGE mass was associated with the occurrence of repetitive VEBs (P = 0.002). Lower LV stroke volume (P = 0.017), lower RVEF (P = 0.016), a higher LVMi/LVEDVI ratio (P = 0.016), fatty infiltration (P = 0.04), and LGE extent (P < 0.001) were associated with death.

CONCLUSION

DM1 patients display structural and functional cardiac abnormalities, with variable degrees of cardiac muscle hypotrophy, fibrosis, and fatty infiltration. Such changes, as evaluated by CMR, seem to be associated with the development of ventricular arrhythmias and a worse outcome.

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.

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.

Myotonic dystrophy and the heart: A systematic review of evaluation and management

Myotonic dystrophy (MD) is a multisystem, autosomal dominant disorder best known for its skeletal muscle manifestations. Cardiac manifestations arise as a result of myocardial fatty infiltration, degeneration and fibrosis and present most commonly as arrhythmias or conduction disturbances. Guidelines regarding the optimal cardiac management of patients with MD are lacking. The present article provides a summary of the pathophysiology of cardiac problems in patients with MD and provides a practical approach to contemporary cardiac monitoring and management of these patients with a focus on the prevention of complications related to conduction disturbances and arrhythmias.

METHODS

A literature search was performed using PubMed and Medline. The keywords used in the search included "myotonic dystrophy", "cardiac manifestations", "heart", "arrhythmia", "pacemaker" and "defibrillator", all terms were used in combination. In addition, "myotonic dystrophy" was searched in conjunction with "electrophysiology", "electrocardiogram", "echocardiograph", "signal averaged electrocardiograph", "magnetic resonance imaging" and "exercise stress testing". The titles of all the articles revealed by the search were screened for relevance. The abstracts of relevant titles were read and those articles which concerned the cardiac manifestations of myotonic dystrophy or the investigation and management of cardiac manifestations underwent a full manuscript review.

Cardiac manifestations in myotonic dystrophy type 1 patients followed using a standard protocol in a specialized unit

INTRODUCTION AND OBJECTIVES

Myotonic dystrophy type 1 is characterized by muscle damage and systemic manifestations, including cardiac involvement. Our aim was to document the frequency and severity of cardiac involvement (left ventricular dysfunction and arrhythmia or conduction disorders), the need for a pacemaker, implantable cardioverter-defibrillator, or electrophysiological study, and the development of sudden death during follow-up.

METHODS

Retrospective observational study of myotonic dystrophy type 1 patients referred to a specialized cardiac unit. Patients received clinical, electrocardiographic (Holter monitoring), and echocardiographic follow-up.

RESULTS

We included 81 patients (51.9% men; mean age, 29.9 [14.8] years). The mean follow-up was 5.7 (3.9) years (range: 1-20 years). During this period sinus bradycardia was documented in 48.8%, PR interval≥220 ms in 31.3%, long corrected QT interval in 5%, and QRS interval≥120 ms in 7.5%. A total of 13.8% of patients developed sinus node dysfunction, 10% of patients had supraventricular arrhythmias, 5% had ventricular tachycardia, and 8.8% developed second- or third- degree atrioventricular block. Only 1 patient had severe ventricular dysfunction. During the follow-up, 15 pacemakers and 2 implantable cardioverter-defibrillators were implanted and 5 electrophysiological studies were performed (mainly due to ventricular tachycardia). There was only 1 sudden death.

CONCLUSIONS

Arrhythmia or conduction disorders are frequent during the course of myotonic dystrophy type 1 patients. A significant percentage of patients require electrophysiological study and the use of a device (pacemaker or implantable cardioverter-defibrillator). In our experience, systolic dysfunction and sudden death are rare.

Assessment of cardiac involvement in myotonic muscular dystrophy by T1 mapping on magnetic resonance imaging

BACKGROUND

Patients with myotonic muscular dystrophy (DM) are at risk for atrioventricular block and left ventricular (LV) dysfunction. Noninvasive detection of diffuse myocardial fibrosis may improve disease management in this population.

OBJECTIVE

To define functional and postcontrast myocardial T1 time cardiac magnetic resonance characteristics in patients with DM.

METHODS

Thirty-three patients with DM (24 with type 1 and 9 with type 2) and 13 healthy volunteers underwent cardiac magnetic resonance for the assessment of LV indices and the evaluation of diffuse myocardial fibrosis by T1 mapping. The association of myocardial T1 time with electrocardiogram abnormalities and LV indices was examined among patients with DM.

RESULTS

Patients with DM had lower end-diastolic volume index (68.9 mL/m(2) vs 60.3 mL/m(2); P = .045) and cardiac index (2.7 L/min/m(2) vs 2.33 L/min/m(2); P = .005) and shorter myocardial T1 time (394.5 ms vs 441.4 ms; P < .0001) than did control subjects. Among patients with DM, there was a positive association between higher T1 time and LV mass index (2.2 ms longer per g/m(2); P = .006), LV end-diastolic volume index (1.3 ms longer per mL/m(2); P = .026), filtered QRS duration (1.2 ms longer per unit; P = .005), and low-amplitude (<40 mcV) late-potential duration (0.9 ms longer per unit; P = .01). Using multivariate random effects regression, each 10-ms increase in myocardial T1 time of patients with type 1 DM was independently associated with 1.3-ms increase in longitudinal PR and QRS intervals during follow-up.

CONCLUSIONS

DM is associated with structural alterations on cardiac magnetic resonance. Postcontrast myocardial T1 time was shorter in patients with DM than in controls, likely reflecting the presence of diffuse myocardial fibrosis.