A Normal Electrocardiogram Does Not Exclude Infra-Hisian Conduction Disease in Patients With Myotonic Dystrophy Type
Antonio Creta1, Rui Providência2, Thomas Gossios3
1Barts Heart Centre, St. Bartholomew's Hospital, London, United Kingdom; Campus Bio-Medico, University of Rome, Rome, Italy.
JACC. Clinical Electrophysiology
|April 4, 2021
Summary
Electrocardiogram (ECG) predictors for prolonged His-ventricular (HV) intervals in type 1 myotonic dystrophy (DM1) are unreliable. Electrophysiology testing is crucial for screening DM1 patients to guide pacemaker implantation.
Area of Science:
- Cardiology
- Genetics
- Electrophysiology
Background:
- Type 1 myotonic dystrophy (DM1) increases the risk of sudden cardiac death.
- Prolonged His-ventricular (HV) interval (≥70 ms) indicates His-Purkinje system disease and elevates the risk of bradyarrhythmic events.
Purpose of the Study:
- To identify electrocardiographic (ECG) predictors of a prolonged HV interval in DM1 patients.
- To assess the diagnostic utility of ECG parameters in predicting infra-Hisian conduction block.
Main Methods:
- Electrophysiology studies (EPSs) were conducted in 154 DM1 patients across two centers.
- Repeated EPSs were performed in a subgroup to evaluate interval changes over time.
- Receiver operating characteristic (ROC) curve analysis and multivariate analysis were used to determine predictive values.
Main Results:
- A prolonged HV interval (≥70 ms) was detected in 28.7% of EPSs.
- QRS duration showed the strongest discriminative capacity for HV ≥70 ms (AUC: 0.76).
- A QRS interval ≥112 ms was the most significant predictor of a prolonged HV interval (OR: 7.94).
Conclusions:
- Standard ECG parameters have limited predictive value for infra-Hisian conduction block in DM1.
- A significant proportion of DM1 patients with normal baseline ECG findings or prolonged PR/QRS intervals may still have advanced conduction system disease.
- Electrophysiology testing is essential for comprehensive screening and guiding prophylactic pacemaker implantation in DM1 patients.
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