Résumé :
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Background: Patients presenting with myotonic dystrophy type 1 (DM1) undergo either a non-invasive strategy (NIS) and permanent pacing if major abnormalities of impulse propagation are detected on the electrocardiogram (ECG), or an invasive strategy (IS) with electrophysiological studies (EPS) and prophylactic pacing if the HV interval is >70 ms. We compared the effects of the two strategies on long-term survival. Methods: Between January 2000 and December 2009, the DM1 Heart Registry included 914 patients suffering from DM1. We compared the overall survival and incidence of sudden death among 341 patients (70, 1%) who underwent IS versus 145 (29, 8%) who underwent NIS, out of 486 patients whose ECG showed major conduction abnormalities. We accounted for possible selection biases by using a propensity-score risk adjustment and propensity based matching analysis. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated. Findings: The median follow-up was 7, 4 years (range 0 to 9, 9). The 9-year survival rate was higher (79, 0%; 95% CI 73, 6-84, 8 vs. 69, 2%; 95% CI 59, 7-80, 3) and the cumulative incidence of sudden death was lower (4, 1%; 95% CI 2, 0-7, 4 vs. 18, 0%; 95% CI 10, 2-27, 4) in the IS than in the NIS group. Regardless of the statistical technique used to adjust for differences in baseline characteristics between the two groups, IS was associated with a longer survival, with HR ranging from 0, 53 (95% CI 0, 33-0, 86, p=0, 010) to 0, 59 (0, 37-0, 95, p=0, 031), and a lower incidence of sudden death, with HR ranging from 0, 21 (95% CI 0, 08-0, 55) to 0, 25 (95% CI 0, 11-0, 56). The rates of death from non-cardiac causes were similar in both groups. Interpretation: An initial EPS-based evaluation of impulse propagation abnormalities in patients suffering from DM1 was associated with a higher 9-year survival due to a lower rate of sudden death. Funding: This study was funded by grants from the Association Française contre les Myopathies (French Alliance against Myopathies)
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