Electrocardiographic abnormalities and sudden death in myotonic dystrophy type 1
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Published on: April 5, 2011
William J Groh1, Miriam R Groh, Chandan Saha
1Department of Medicine, Krannert Institute of Cardiology, Indiana University, Indianapolis 46202, USA. wgroh@iupui.edu
Insights
Sudden death risk in myotonic dystrophy type 1 (DM1) patients can be predicted by electrocardiogram (ECG) abnormalities. Severe ECG findings and atrial tachyarrhythmia significantly increase the likelihood of sudden cardiac death in DM1 individuals.
Area of Science:
- Cardiology
- Neurology
- Genetics
Background:
- Myotonic dystrophy type 1 (DM1) is a neuromuscular disease associated with cardiac conduction abnormalities and sudden death.
- The precise risk factors for sudden death in DM1 patients are not well-defined.
Purpose of the Study:
- To evaluate the utility of electrocardiogram (ECG) in predicting sudden death in adult patients with genetically confirmed myotonic dystrophy type 1.
Main Methods:
- Assessed 406 adult DM1 patients using ECG criteria for severe abnormalities (e.g., abnormal rhythm, prolonged PR/QRS intervals, heart block).
- Correlated ECG findings with clinical outcomes, including sudden death, over a mean follow-up of 5.7 years.
Main Results:
- Severe ECG abnormalities were linked to older age, more severe muscle impairment, and higher rates of heart failure and atrial tachyarrhythmia.
- A severe ECG abnormality (RR 3.30) and atrial tachyarrhythmia (RR 5.18) were independent predictors of sudden death.
- During follow-up, 27 of 81 deaths were sudden, with ventricular tachyarrhythmia observed in 9 cases.
Conclusions:
- Adult DM1 patients face a high risk of arrhythmias and sudden cardiac death.
- Electrocardiogram abnormalities and atrial tachyarrhythmia diagnosis are crucial predictors of sudden death in DM1.
Background:
Sudden death can occur as a consequence of cardiac-conduction abnormalities in the neuromuscular disease myotonic dystrophy type 1. The determinants of the risk of sudden death remain imprecise.
Methods:
We assessed whether the electrocardiogram (ECG) was useful in predicting sudden death in 406 adult patients with genetically confirmed myotonic dystrophy type 1. A patient was characterized as having a severe abnormality if the ECG had at least one of the following features: rhythm other than sinus, PR interval of 240 msec or more, QRS duration of 120 msec or more, or second-degree or third-degree atrioventricular block.
Results:
Patients with severe abnormalities according to the entry ECG were older than patients without severe abnormalities, had more severe skeletal-muscle impairment, and were more likely to have heart failure, left ventricular systolic dysfunction, or atrial tachyarrhythmia. Such patients were more likely to receive a pacemaker or an implantable cardioverter-defibrillator during the follow-up period. During a mean follow-up period of 5.7 years, 81 patients died; there were 27 sudden deaths, 32 deaths from progressive neuromuscular respiratory failure, 5 nonsudden deaths from cardiac causes, and 17 deaths from other causes. Among the 17 patients who died suddenly in whom postcollapse rhythm was evaluated, a ventricular tachyarrhythmia was observed in 9. A severe ECG abnormality (relative risk, 3.30; 95% confidence interval [CI], 1.24 to 8.78) and a clinical diagnosis of atrial tachyarrhythmia (relative risk, 5.18; 95% CI, 2.28 to 11.77) were independent risk factors for sudden death.
Conclusions:
Patients with adult myotonic dystrophy type 1 are at high risk for arrhythmias and sudden death. A severe abnormality on the ECG and a diagnosis of an atrial tachyarrhythmia predict sudden death. (ClinicalTrials.gov number, NCT00622453.)
