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The evolution of infrahissian conduction time in myotonic dystrophy patients: clinical implications
Bénédicte Lallemand1, Nicolas Clementy, Anne Bernard-Brunet
1Cardiology Department, Hospital Trousseau, François Rabelais University, 37044 Tours, France.
Insights
Myotonic dystrophy patients with normal initial tests showed worsening infrahissian conduction over time. Resting and signal-averaged ECG changes predict these cardiac conduction disturbances.
Area of Science:
- Cardiology
- Neurology
- Genetics
Background:
- Myotonic dystrophy (MD1) is an inherited condition with variable symptoms.
- Cardiac conduction problems are common in MD1 and can lead to sudden death.
- The progression of cardiac conduction issues in MD1 is not well understood.
Purpose of the Study:
- To investigate the natural progression of infrahissian conduction time in MD1 patients.
- To identify clinical and ECG factors that predict changes in infrahissian conduction.
Main Methods:
- 25 MD1 patients with normal initial electrophysiological tests were re-evaluated.
- Second tests were performed for new symptoms, ECG changes, or SA-ECG modifications.
- Asymptomatic patients underwent follow-up for at least 60 months.
Main Results:
- The His-ventricle (HV) interval significantly increased over time (mean 1.2 ms/year).
- Four patients developed new symptoms, four new AV conduction abnormalities, and six had SA-ECG changes.
- Resting and SA-ECG modifications correlated strongly with HV interval prolongation.
Conclusions:
- In MD1 patients with initially normal electrophysiology, ECG changes indicate worsening infrahissian conduction.
- Annual ECG monitoring can help detect progression of cardiac conduction abnormalities.
Background:
Myotonic dystrophy (MD1) is a hereditary autosomal dominant disease with variable penetrance. Cardiac conduction disturbances are frequent and may be responsible for sudden death, but its progression was heretofore unknown.
Aims:
The aim of the study was to analyse the natural history of infrahissian conduction time in patients with a normal first electrophysiological test, and to identify the predictive value of the clinical and ECG factors accompanying an alteration of infrahissian conduction.
Methods:
Among 127 consecutive screened MD patients, 25 were enrolled and underwent a second electrophysiological testing. The second electrophysiological test was carried out on patients showing new symptoms, new atrioventricular conduction disturbances on ECG, or significant modifications of signal-averaged (SA)-ECG, and on asymptomatic patients with a follow-up of at least 60 months since the first electrophysiological test.
Results:
Among the 25 patients, four had new clinical symptoms, four others developed new atrioventricular conduction abnormalities on ECG and six had significant modifications of the SA-ECG. The mean His-ventricle (HV) interval increased significantly between the two electrophysiological studies (initial HV interval 52.1 ms±1.6 ms, final HV interval 61.4 ms±2.2 ms, p<0.005), with a mean increase of 1.2 ms/year. The five patients with HV interval of 70 ms or greater were implanted with a prophylactic dual-chamber pacemaker. Modifications of resting ECG and SA-ECG were strongly associated with HV interval prolongation.
Conclusion:
In patients with a normal initial electrophysiological study, modifications on the resting ECG and/or SA-ECG, on annual check-up, were associated with an alteration of infrahissian conduction.
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