S.P.27 Electrophysiological study with prophylactic pacing and survival in adults with myotonic dystrophy and conduction system disease

Abstract Up to one-third of patients with myotonic dystrophy type 1 (DM1) die suddenly. Thus far, no intervention has effectively prevented sudden death. The objective was to determine whether an invasive strategy (IS) based on systematic electrophysiological studies and prophylactic permanent pacing is associated with longer survival in patients presenting with DM1 and major infranodal conduction delays than a noninvasive strategy (NIS). A retrospective study, the DM1 Heart Registry, included 914 consecutive patients older than 18 years with genetically confirmed DM1 who were admitted to the Myology Institute of Pitié-Salpêtrière Hospital, between January 2000 and December 2009. Among 486 patients whose electrocardiogram showed a PR interval greater than 200 ms, a QRS duration greater than 100 ms, or both, we compared the outcome of 341 (70.2%) who underwent an IS was compared with 145 (29.8%) who underwent a NIS. A propensity score risk adjustment and propensity-based matching analysis was used to account for selection biases. Over a median follow-up of 7.4 years (range 0–9.9 years), 50 patients died in the IS group and 30 died in the NIS group (hazard ratio [HR], 0.74 [95 CI, 0.47–1.16]; P = .19), corresponding to an overall 9-year survival of 74.4% (95% CI, 69.2%–79.9%). Regardless of the technique used to adjust for between-group differences in baseline characteristics, the IS was associated with a longer survival, with adjusted HRs ranging from 0.47 (95% CI, 0.26–0.84; P = .01) to 0.61 (95% CI, 0.38–0.99; P = .047). The survival difference was largely attributable to a lower incidence of sudden death, which occurred in 10 patients in the IS group and in 16 patients in the NIS group, with HRs ranging from 0.24 (95% CI, 0.10–0.56; P = .001) to 0.28 (95% CI, 0.13–0.61; P = .001). Among patients with DM1, an invasive strategy was associated with a higher rate of 9-year survival than a noninvasive strategy.