Development and Validation of a New Scoring System to Predict Survival in Patients With Myotonic Dystrophy Type 1.

Importance: Life expectancy is greatly shortened in patients presenting with myotonic dystrophy type 1 (DM1), the most common neuromuscular disease. A reliable prediction of survival in patients with DM1 is critically important to plan personalized health supervision. Objective: To develop and validate a prognostic score to predict 10-year survival in patients with DM1. Design, Setting, and Participants: In this longitudinal cohort study, between January 2000 and November 2014, we enrolled 1296 adults referred to 4 tertiary neuromuscular centers in France for management of genetically proven DM1, including 1066 patients in the derivation cohort and 230 in the validation cohort. Data were analyzed from December 2016 to March 2017. Main Outcomes and Measures: Factors associated with survival by multiple variable Cox modeling, including 95% confidence intervals, and development of a predictive score validated internally and externally. Mean values are reported with their standard deviations. Results: Of the 1296 included patients, 670 (51.7%) were women, and the mean (SD) age was 39.8 (13.7) years. Among the 1066 patients (82.3%) in the derivation cohort, 241 (22.6%) died over a median (interquartile range) follow-up of 11.7 (7.7-14.3) years. Age, diabetes, need for support when walking, heart rate, systolic blood pressure, first-degree atrioventricular block, bundle-branch block, and lung vital capacity were associated with death. Simplified score points were attributed to each predictor, and adding these points yielded scores between 0 and 20, with 0 indicating the lowest and 20 the highest risk of death. The 10-year survival rate was 96.6% (95% CI, 94.4-98.9) in the group with 0 to 4 points, 92.2% (95% CI, 88.8-95.6) in the group with 5 to 7 points, 80.7% (95% CI, 75.4-86.1) in the group with 8 to 10 points, 57.9% (95% CI, 49.2-66.6) in the group with 11 to 13 points, and 19.4% (95% CI, 8.6-30.1) in the group with 14 points or more. In 230 patients (17.7%) included in the validation cohort, the 10-year survival rates for the groups with 0 to 4, 5 to 7, 8 to 10, 11 to 13, and 14 points or more were 99.3% (95% CI, 95.0-100), 80.6% (95% CI, 67.1-96.7), 79.3% (95% CI, 66.2-95.1), 43.2% (95% CI, 28.2-66.1), and 21.6% (95% CI, 10.0-46.8), respectively. The calibration curves did not deviate from the reference line. The C index was 0.753 (95% CI, 0.722-0.785) in the derivation cohort and 0.806 (95% CI, 0.758-0.855) in the validation cohort. Conclusions and Relevance: The DM1 prognostic score is associated with long-term survival.

Gender as a Modifying Factor Influencing Myotonic Dystrophy Type 1 Phenotype Severity and Mortality: A Nationwide Multiple Databases Cross-Sectional Observational Study.

BACKGROUND: Myotonic Dystrophy type 1 (DM1) is one of the most heterogeneous hereditary disease in terms of age of onset, clinical manifestations, and severity, challenging both medical management and clinical trials. The CTG expansion size is the main factor determining the age of onset although no factor can finely predict phenotype and prognosis. Differences between males and females have not been specifically reported. Our aim is to study gender impact on DM1 phenotype and severity. METHODS: We first performed cross-sectional analysis of main multiorgan clinical parameters in 1409 adult DM1 patients (>18 y) from the DM-Scope nationwide registry and observed different patterns in males and females. Then, we assessed gender impact on social and economic domains using the AFM-Téléthon DM1 survey (n = 970), and morbidity and mortality using the French National Health Service Database (n = 3301). RESULTS: Men more frequently had (1) severe muscular disability with marked myotonia, muscle weakness, cardiac, and respiratory involvement; (2) developmental abnormalities with facial dysmorphism and cognitive impairment inferred from low educational levels and work in specialized environments; and (3) lonely life. Alternatively, women more frequently had cataracts, dysphagia, digestive tract dysfunction, incontinence, thyroid disorder and obesity. Most differences were out of proportion to those observed in the general population. Compared to women, males were more affected in their social and economic life. In addition, they were more frequently hospitalized for cardiac problems, and had a higher mortality rate. CONCLUSION: Gender is a previously unrecognized factor influencing DM1 clinical profile and severity of the disease, with worse socio-economic consequences of the disease and higher morbidity and mortality in males. Gender should be considered in the design of both stratified medical management and clinical trials.

The evolution of infrahissian conduction time in myotonic dystrophy patients: clinical implications.

BACKGROUND: Myotonic dystrophy (MD1) is a hereditary autosomal dominant disease with variable penetrance. Cardiac conduction disturbances are frequent and may be responsible for sudden death, but its progression was heretofore unknown. AIMS: The aim of the study was to analyse the natural history of infrahissian conduction time in patients with a normal first electrophysiological test, and to identify the predictive value of the clinical and ECG factors accompanying an alteration of infrahissian conduction. METHODS: Among 127 consecutive screened MD patients, 25 were enrolled and underwent a second electrophysiological testing. The second electrophysiological test was carried out on patients showing new symptoms, new atrioventricular conduction disturbances on ECG, or significant modifications of signal-averaged (SA)-ECG, and on asymptomatic patients with a follow-up of at least 60 months since the first electrophysiological test. RESULTS: Among the 25 patients, four had new clinical symptoms, four others developed new atrioventricular conduction abnormalities on ECG and six had significant modifications of the SA-ECG. The mean His-ventricle (HV) interval increased significantly between the two electrophysiological studies (initial HV interval 52.1 ms±1.6 ms, final HV interval 61.4 ms±2.2 ms, p<0.005), with a mean increase of 1.2 ms/year. The five patients with HV interval of 70 ms or greater were implanted with a prophylactic dual-chamber pacemaker. Modifications of resting ECG and SA-ECG were strongly associated with HV interval prolongation. CONCLUSION: In patients with a normal initial electrophysiological study, modifications on the resting ECG and/or SA-ECG, on annual check-up, were associated with an alteration of infrahissian conduction.

[When do you implant a pacemaker in myotonic dystrophy?]. / Quand implanter un stimulateur cardiaque dans la maladie de Steinert?

Myotonic dystrophy is the most frequent adult form of hereditary muscular dystrophy caused by a mutation on the DMPK gene. Myotonic dystrophy leads to multiple systemic complications related to weakness, respiratory failure, cardiac arrhythmias and cardiac conduction disturbances. Age of death is earlier in myotonic dystrophy patients than in general population with a high frequency of sudden death. Several mechanisms are involved in sudden death: atrio-ventricular block, severe ventricular arrhythmias or non-cardiac mechanism. The high degree of atrio-ventricular block is a well-recognized indication of pacemaker implantation but the prophylactic implantation of pacemaker should be considered to prevent sudden death in asymptomatic myotonic dystrophy patients. A careful clinical evaluation needs to be done for the identification of patients at high risk of sudden death. The resting ECG and SA ECG are non-invasive tools useful to select the patients who need an electrophysiologic study. In presence of prolonged HV interval more than or equal to 70 ms one can discuss the implantation of a prophylactic pacemaker. The choice of an implantable cardiac defibrillator is preferred in presence of spontaneous ventricular tachycardia or an alteration of the left ventricular ejection fraction.

Mortality in myotonic dystrophy patients in the area of prophylactic pacing devices.

OBJECTIVES: Our study purports to determine whether implantation of a prophylactic pacemaker in MD patients with HV interval ≥ 70 ms lowers the risk of sudden death, which may be essentially due to complete atrioventricular block. BACKGROUND: Sudden death occurs more frequently in patients with myotonic dystrophy (MD) than in the control population. METHODS: From 1994 to 2008, 100 consecutive patients were enrolled, 49 of whom were implanted. RESULTS: During an average follow-up of 74 ± 39 months, 10 deaths occurred. Nine were due to respiratory failure. Only one sudden death occurred, whereas 46% of patients were considered at risk of sudden death according to the criteria of Groh et al. [5]. The incidence rate of sudden death was only 0.2 per 100 patient-years. One patient developed a paroxysmal syncopal sustained ventricular tachycardia. CONCLUSIONS: The prophylactic implantation of PM in MD patients who are identified as being at risk of sudden death according to Groh's criteria reduced the incidence rate of sudden death. The one sudden death in an implanted MD patient suggests the likelihood that pacemaker implantation did not totally forestall this event. Ventricular arrhythmias may be involved in the sudden deaths in MD patients, in which case the implantation of an implantable cardiac defibrillator could be indicated.