Cardiac pacing in myotonic dystrophy type 1: a retrospective cohort study on indications, diagnostic modalities, and long-term outcomes.

BACKGROUND AND AIMS: Patients with myotonic dystrophy type 1 (DM1) are at increased risk of sudden cardiac death, and cardiac screening is recommended to identify patients who may benefit from cardiac pacing. We evaluated indications for cardiac implantable electronic device (CIED) implantation, diagnostic modalities used, and long-term ventricular pacing burden and mortality.

METHODS

This retrospective observational cohort study included adults with DM1 in western Sweden, referred for CIED implantation between January 2000 and March 2023. Patient characteristics, ECG and Holter findings, pacing burden, and survival were obtained from electronic health records.

RESULTS

In total, 102 patients (mean age 50 ± 14 years, 44% women) underwent prophylactic CIED implantation during routine cardiac surveillance. CIED implantations were based on screening ECG findings in 53 patients and Holter monitoring in 49 patients. ECG predominantly identified PR and QRS prolongation corresponding to Class IIb indications, whereas Holter monitoring frequently detected intermittent second-degree atrioventricular block, a Class I indication. Median (IQR) follow-up after prophylactic implantation was 5 (4-5) years. Ventricular pacing burden increased over time; at last follow-up, approximately one-third of patients reached a ventricular pacing burden >40%. All-cause mortality was 21% (n = 21), mainly due to respiratory insufficiency and infections.

CONCLUSION

Combined ECG and Holter screening may provide complementary information for identifying pacing indications in patients with DM1. Ventricular pacing burden increased over time. Mortality was predominantly non-arrhythmic.