The multicenter cohort analysis, led by Dr. Nicolas Clementy of the Department of Cardiology at Université de Tours, CHU de Tours, Paris, France, evaluated 706 adults with genetically confirmed DM1 drawn from the DM1 Heart Registry. The study aimed to determine whether ECG or EPS criteria better predict major bradyarrhythmic events (MBAEs), which include sudden cardiac death, resuscitated cardiac arrest, or advanced atrioventricular block.
The study revealed the following findings:
- Participants had a median follow-up of nearly six years.
- At baseline, 38% of patients had a His-ventricular (HV) interval ≥70 milliseconds.
- At baseline, 32% of patients met ECG-based criteria (PR interval ≥240 milliseconds or QRS duration ≥120 milliseconds).
- During follow-up, 14% of patients experienced a major bradyarrhythmic event (MBAE).
- Multivariable analysis showed that the HV interval was the only variable significantly associated with MBAE incidence.
- An HV interval ≥70 milliseconds was a stronger predictor of MBAEs than ECG criteria, with hazard ratios of 2.89 versus 1.95.
- EPS correctly identified 68.35% of patients at risk, compared with 34.76% for ECG-based assessment.
- Lowering the HV threshold to 65 milliseconds increased sensitivity to over 90% and improved net patient reclassification by 33.7%.
According to the researchers, these results suggest that EPS allows for more precise risk stratification in DM1 patients, potentially guiding timely prophylactic pacemaker implantation and preventing sudden cardiac death. In contrast, reliance on ECG criteria alone may underestimate risk in a substantial proportion of patients, potentially leaving high-risk individuals unprotected.
Professional practice guidelines currently recommend prophylactic pacemaker implantation in asymptomatic DM1 patients who meet ECG or EPS thresholds as class IIa indications. This study provides strong evidence that EPS, particularly HV interval assessment, may be the more reliable method for selecting patients who would benefit most from pacing.
The authors note that adopting a slightly lower HV threshold could further optimize patient care by identifying more at-risk individuals without significantly increasing unnecessary interventions. While the study is retrospective and observational, it is strengthened by a large, multicenter cohort and long-term follow-up.
"The study highlights the clinical value of electrophysiological evaluation over ECG in DM1. Using EPS to guide prophylactic pacemaker implantation could significantly improve outcomes by accurately identifying patients at the highest risk for major bradyarrhythmic events, ultimately enhancing both survival and quality of care in this vulnerable population," the authors concluded.
Reference:
Clementy N, Labombarda F, Grolleau F, et al. Electrocardiogram vs Electrophysiological Study and Major Conduction Delays in Myotonic Dystrophy Type 1. JAMA Cardiol. Published online September 24, 2025. doi:10.1001/jamacardio.2025.3055
Disclaimer: This website is primarily for healthcare professionals. The content here does not replace medical advice and should not be used as medical, diagnostic, endorsement, treatment, or prescription advice. Medical science evolves rapidly, and we strive to keep our information current. If you find any discrepancies, please contact us at corrections@medicaldialogues.in. Read our Correction Policy here. Nothing here should be used as a substitute for medical advice, diagnosis, or treatment. We do not endorse any healthcare advice that contradicts a physician's guidance. Use of this site is subject to our Terms of Use, Privacy Policy, and Advertisement Policy. For more details, read our Full Disclaimer here.
NOTE: Join us in combating medical misinformation. If you encounter a questionable health, medical, or medical education claim, email us at factcheck@medicaldialogues.in for evaluation.