Abstract
BackgroundConduction disease and arrhythmias represent a major cause of mortality in myotonic muscular dystrophy type 1 (MMD1). Permanent pacemaker (PPM) implantation is the cornerstone of therapy to reduce cardiovascular mortality in MMD1. Cardiovascular magnetic resonance (CMR) studies demonstrate a high prevalence of myocardial fibrosis in MMD1, however the association between CMR myocardial fibrosis with late gadolinium enhancement (CMR-LGE) and surface conduction abnormality is not well established in MMD1.We investigated whether myocardial fibrosis by CMR-LGE is associated with surface conduction abnormalities meeting criteria for PPM implantation according to current guidelines in a cohort of patients with genetically confirmed MMD1.MethodsPatients with genetically confirmed MMD1 were retrospectively evaluated. 12-lead electrocardiography (ECG) performed within 6 months of CMR was necessary for inclusion. The severity and extent of MMD1 was quantified using a validated Muscular Impairment Rating Scale (MIRS). Based on current guidelines for device-based therapy of cardiac rhythm abnormalities, we defined surface conduction abnormality as the presence of ECG alterations meeting criteria for PPM implant (class I or II indications): PR interval > 200 ms (type I atrioventricular (AV) block) and/or mono or bifascicular block (QRS > 120 ms), or evidence of advanced AV block. Balanced steady-state free precession sequences (bSSFP) were used for assessment of left ventricular (LV) volumes and ejection fraction. MOdified Look-Locker Inversion Recovery (MOLLI) acquisition schemes were used to acquire T1 maps. Patients’ charts were reviewed up to 12 months post-CMR for occurrence of PPM implantation.ResultsFifty-two patients (38% male, 41 ± 14 years) were included. Overall, 31 (60%) patients had a surface conduction abnormality and 22 (42%) demonstrated midwall myocardial fibrosis by CMR-LGE. After a median of 57 days from CMR exam, 15 patients (29%) underwent PPM implantation. Subjects with vs. without surface conduction abnormality had significantly longer disease length (15.5 vs. 7.8 years, p = 0.015) and higher disease severity on the MIRS scale (p = 0.041). High prevalence of myocardial fibrosis by CMR-LGE was detected in subjects with and without surface conduction abnormality with no significant difference between the two cohorts (42% vs. 43%, p = 0.999). By multivariate logistic regression analysis, disease length was the only independent variable associated with surface conduction abnormality (OR 1.071, 95%CI 1.003–1.144, p = 0.040); while CMR-LGE was not associated with conduction abnormality (ρ = − 0.009, p = 0.949).ConclusionsMyocardial fibrosis by CMR-LGE is highly prevalent in MMD1 but not related to surface conduction abnormality meeting current guideline criteria for PPM implantation .
Highlights
Myotonic muscular dystrophy type 1 (MMD1) is the most common muscular dystrophy in adults and is characterized by progressive muscle degeneration leading to disabling weakness and wasting with myotonia, in combination with multisystem involvement [1]
Permanent pacing has been recommended by the American College of Cardiology and the American Heart Association when complete AV block or advanced high-degree AV block are detected, or prophylactically for patients presenting with first-degree AV or fascicular block on the ECG [5]
Thirty-one patients (60%) demonstrated surface conduction abnormality: 20 (38%) with a prolonged PR interval; 5 (9.6%) with a prolonged PR interval associated with right bundle branch block (RBBB); 2 (3.8%) patients had a prolonged PR interval associated with left bundle branch block (LBBB); 2 (3.8%) had LBBB alone, one patient had RBBB alone, and one had Mobitz AV block type I
Summary
Myotonic muscular dystrophy type 1 (MMD1) is the most common muscular dystrophy in adults and is characterized by progressive muscle degeneration leading to disabling weakness and wasting with myotonia, in combination with multisystem involvement [1]. Cardiac involvement initially manifests as asymptomatic electrocardiographic (ECG) abnormalities, typically prolongation of the PR and QRS intervals progressing to more advanced conduction disease including sinus node dysfunction and heart block as well as atrial tachycardia, and ventricular tachycardia or fibrillation [3,4,5]. Progression of conduction system disease to complete atrioventricular (AV) block is the presumed cause of SCD in a high proportion of patients [3,4,5]. Implantation of a permanent pacemaker (PPM) has been found useful even in asymptomatic patients with an abnormal resting ECG or with HV interval prolongation during electrophysiological study as the disease course can have unpredictable progression to advanced conduction disease [5, 6]. Conduction disease and arrhythmias represent a major cause of mortality in myotonic muscular dystrophy type 1 (MMD1). We investigated whether myocardial fibrosis by CMR-LGE is associated with surface conduction abnormalities meeting criteria for PPM implantation according to current guidelines in a cohort of patients with genetically confirmed MMD1
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
