Cardiac involvement in myotonic dystrophy: A nationwide cohort study

Abstract

Aims: To quantify the association between myotonic dystrophy (DM) and cardiac disease in a nationwide cohort. Methods and results: We identified a nationwide cohort of 1146 DM patients (period 1977-2011) using the National Patient Registry (NPR) and a subcohort of 485 patientswhohad undergone genetic testing forDM1.Information on incident cardiac diseaseswas obtained from the NPR.We estimated standardized incidence ratios (SIRs) of cardiac disease compared with the background population, overall and according to selected diagnostic subgroups (cardiomyopathy, heart failure, conduction disorders, arrhythmias, and device implantation). In theDMcohort, SIR for any cardiac diseasewas 3.42 [95% confidence interval (CI) 3.01-3.86]; for a cardiac disease belonging to the selected subgroups 6.91 (95% CI: 5.93-8.01) and for other cardiac disease 2.59 (95% CI: 2.03-3.25). For a cardiac disease belonging to the selected subgroups, the riskwas particularly high in the first year afterDM diagnosis [SIR 15.4 (95% CI: 10.9-21.3)] but remained significantly elevated in subsequent years [SIR 6.07 (95% CI: 5.11-7.16]). The riskwas higher in young cohortmembers [e.g. 20-39 years: SIR 18.1 (95% CI: 12.3-25.8)] compared with older [e.g. 60-79 years: SIR 3.99 (95% CI: 2.98-5.23)] but remained significantly increased in all age categories. Results were similar in separate analyses of the genetically confirmed DM1 patients. Conclusion: Myotonic dystrophy is strongly associated with cardiac disease. The risk is pronounced in the young and remains elevated throughout life, stressing the importance of lifelong cardiac follow-up from time of DM diagnosis. ©The Author 2014.