Abstract 14674: High Prevalence of Cardiac Involvement in Patients With Myotonic Dystrophy Type 1 - A Cross-Sectional Cohort Study
Objectives: To describe cardiac involvement in patients with myotonic dystrophy type 1 (DM1) and the relation to age, gender and neuromuscular involvement in order to optimize recommendations for cardiac assessment and follow-up.
Background: In the inherited progressive neuromuscular disorder DM1, cardiac involvement is common and the risk of sudden cardiac death (SCD) is approximately three fold higher than in age-matched healthy controls. The cardiac phenotype is complex and progression of cardiac abnormalities is often rapid and unpredictable. Reduction of cardiac manifestations and incidences of SCD depend on recommendations for timing and quality of cardiac work-up.
Methods: We included 129 patients with genetically verified DM1 (64 males (49.6%), mean (SD) age 44 (15) years). Patients were evaluated with electrocardiogram (ECG), trans-thoracic echocardiography (TTE) (including longitudinal strain), Holter-monitoring and muscle strength testing.
Results: Overall 71 patients (55%) had cardiac involvement including: 1) Conduction abnormalities: atrio-ventricular block grade 1 (AVBI) 24%, AVBII 6%, right/left bundle branch block 6/3% and QTc > 440 ms 7%; 2) Arrhythmias: frequent premature contractions 6%, atrial fibrillation/flutter 4%, other supraventricular tachyarrhythmia 7%, and non-sustained ventricular tachycardia 4%; or 3) Structural abnormalities: left ventricular ejection fraction (LVEF) ≤ 50% 21% and diastolic dysfunction 5%. Reduced global longitudinal strain was significantly associated with reduced LVEF (r=0.5, p < 0.001) and increased interventricular septum thickness (r=0.3, p < 0.01). ICDs were implanted in 4% of the patients. Almost 1/3 of the patients reported SCDs in their relatives. Patients with abnormal cardiac findings were significantly weaker in muscle strength compared to patients with normal cardiac findings: ankle dorsal flexion (median (range) 4.5 (0-5) vs. 5.0 (3-5), p < 0.01) and handgrip (median 4.0 (0-5) vs. 4.5 (2-5), p= 0.02).
Conclusion: This large cohort of patients with DM1 had a very high prevalence of cardiac involvement and risk factors for SCD. We propose specified recommendations for cardiac assessment and follow-up in order to minimize cardiac manifestations and SCD in these patients.
- © 2013 by American Heart Association, Inc.