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Cardiovascular profile in myotonic dystrophy type 1: Analysis of a case series in a specialized center
Lilian Gomes1, Telmo Pereira2, Luís Martins1
1Hospital de São Sebastião, Santa Maria da Feira, Portugal.
Insights
Myotonic dystrophy type 1 (DM-1) patients frequently experience cardiac conduction abnormalities, including atrioventricular and intraventricular blocks. Larger CTG expansions correlate with increased cardiac involvement in DM-1 patients.
Area of Science:
- Cardiology
- Genetics
- Neurology
Background:
- Myotonic dystrophy is a multisystem disorder linked to significant cardiac issues, impacting morbidity and mortality.
- Conduction tissue is commonly affected, leading to age-related heart rate changes.
Purpose of the Study:
- To evaluate cardiovascular risk and arrhythmia prevalence in myotonic dystrophy type 1 (DM-1) patients.
- To correlate these risks with CTG expansion size from genetic studies.
Main Methods:
- Retrospective analysis of 31 DM-1 patients.
- Cardiac screening included ECG, high-resolution ECG, heart rate variability (HRV), 24-hour Holter monitoring, and echocardiography.
- Correlation with genetic testing results (CTG expansion size).
Main Results:
- 38% had atrioventricular block (AVB), 51% intraventricular conduction disturbances.
- No structural heart disease detected by echocardiography.
- Lower HRV indicated vagal dysfunction; larger CTG expansions correlated with more cardiac abnormalities.
Conclusions:
- DM-1 patients exhibit arrhythmic events, notably AVB and intraventricular block, without malignant arrhythmias or structural heart disease.
- No patient deaths occurred during the study.
- Increased CTG expansion size is associated with greater cardiac conduction tissue involvement.
Introduction:
Myotonic dystrophy is a multisystem disease associated with cardiac abnormalities that are responsible for high morbidity and mortality. It commonly affects conduction tissue, resulting in changes in heart rate that tend to progress with age.
Objective:
The aim of the study was to assess overall cardiovascular risk and the risk of arrhythmias in patients with myotonic dystrophy type 1 (DM-1) and to correlate them with genetic study (CTG expansion size).
Methods:
This retrospective study included 31 DM-1 patients referred to the cardiology department of Centro Hospitalar Entre Douro e Vouga by the neurology department for screening for heart disease. Patients' medical records were consulted for the diagnostic tests performed in the diagnostic cardiology consultation: electrocardiogram (ECG), high-resolution ECG, heart rate variability (HRV), Holter 24-hour ambulatory ECG and transthoracic echocardiogram (TTE); results of genetic testing were also consulted.
Results:
Of 31 patients studied, 38% had first-degree atrioventricular block (AVB) and 51% had intraventricular conduction disturbances (62% had late potentials). TTE revealed no structural heart disease. Rare supraventricular and ventricular ectopic beats were the most common arrhythmias on 24-hour Holter monitoring. The sample showed lower HRV, reflecting vagal dysfunction. Patients with larger CTG expansions had more cardiac abnormalities.
Conclusions:
Patients with DM-1 had arrhythmic events, with AVB and more significantly intraventricular block, although none had malignant arrhythmias or structural heart disease. No patient died. Patients with larger CTG expansions had greater involvement of cardiac conduction tissue.
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