Ventricular stimulation in patients with myotonic dystrophy type 1 may not predict future ventricular arrhythmias

Myotonic dystrophy type 1 (DM1) is associated with progressive conduction disease. Furthermore, DM1 patients are at risk ventricular arrhythmias (VAs), although prediction remains difficult. The 2022 Heart Rhythm Expert Consensus Statement gives a IIb recommendation to the use of electrophysiology study (EPS) to risk-stratify patients for VAs. The utility of EPS in predicting the development of VAs, however, has not been explored in this patient population.

The study sought to examine the natural history of DM1 patients with positive and negative ventricular stimulation (v-stim) during EPS.

Patients with a history of DM1 undergoing EPS with associated v-stim from 2008 to present were retrospectively identified.

From 2008 to 2022, 26 consecutive DM1 patients presented for EPS with v-stim. Four v-stim protocols were positive for sustained or hemodynamically significant ventricular tachycardia (VT), one of which was induced with 600 doubles, the others with triple extrastimuli. A total of 22 of 26 subjects received a device implant, with 18 receiving permanent pacemakers and 4 implantable cardioverter-defibrillators. All 4 of the patients with positive v-stims underwent ICD implantation. After a mean of 5.7 years of follow-up, 7 patients had sustained VT, 6 of whom had negative v-stims. Of the 4 patients with positive v-stims, only 1 developed sustained VT in follow-up. Other than baseline QT interval at time of EPS, no baseline characteristics were significantly different between patients with and without subsequent VT.

In this single center, v-stim in DM1 patients did not predict clinical VAs, as a vast majority of DM1 patients who developed VAs had negative v-stims.