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.
Insights
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.
Objectives:
This study aimed to identify electrocardiographic (ECG) predictors of a prolonged His-ventricular (HV) interval in patients with type 1 myotonic dystrophy (DM1).
Background:
Patients with DM1 have an increased risk of sudden cardiac death. The presence of His-Purkinje system disease/prolonged HV interval (≥70 ms) is associated with a higher risk of potentially life-threatening bradyarrhythmic events.
Methods:
Electrophysiology studies (EPSs) were performed in all DM1 patients referred to 2 tertiary centers for routine cardiac assessment. In a subgroup of patients, the EPS was repeated at varying intervals.
Results:
A total of 154 patients (mean age: 43.7 ± 13.3; 58.1% male) underwent 202 diagnostic EPSs. HV ≥70 ms was found on 58 EPSs (28.7%); 9 of 59 patients (15.2%) with PR <200 ms and QRS interval <110 ms on baseline ECG had an HV ≥70 ms on EPS. Among those with PR ≥200 ms and/or QRS interval ≥100 ms, only 33.9% had an HV ≥70 ms on EPS. There were 38 patients who underwent repeated EPS, in which 28.8% demonstrated a prolongation of the HV interval overall compared with baseline. QRS duration demonstrated the most powerful discriminative capacity for HV ≥70 ms (area under the receiver operating characteristic curve: 0.76; 95% confidence interval [CI]: 0.68 to 0.84; p < 0.001). On multivariate analysis, QRS interval ≥112 ms had the highest predictive value for HV ≥70 ms (odds ratio: 7.94; 95% CI: 3.85 to 16.37.
Conclusions:
ECG parameters have a poor predictive value for infra-Hisian conduction block in DM1 patients. QRS and PR intervals are normal in up to 15.2% of DM1 patients with prolonged HV, and 66.1% of those with PR ≥200 ms and/or QRS ≥100 ms do not have advanced His-Purkinje conduction system disease on EPS. Electrophysiology testing should be a mandatory part of screening for all patients to guide prophylactic pacemaker implantation.
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