Cardiologic predictors of sudden death in patients with myotonic dystrophy type 1.

The aim of this study was to analyze survival, causes of death and cardiologic predictors of sudden death in a large cohort of patients with myotonic dystrophy type 1 (DM1). The study was comprised of 171 adult DM1 patients hospitalized at the Neurology Clinic in a 20-year period. Severe electrocardiographic (ECG) abnormality included at least one of the following: rhythm other than sinus, PR interval of ≥240 ms, QRS complex duration of 120 ms or more, and second-degree or third-degree atrioventricular (AV) block. Survival data were analyzed by the Kaplan-Meier test, log-rank test and Cox regression analysis. During the mean follow-up period of 9.4±5.4 years, a pacemaker was implanted in 5.8% of DM1 patients and 14% of patients died. The mean age at death was 55.6±12.5 years. The most common causes of death in our cohort were sudden death (41.7%) and respiratory failure (29.2%). The presence of palpitations (hazard ratio [HR]=4.7, p<0.05) and increased systolic blood pressure (HR=9.8, p<0.05) were significant predictors of sudden death. Among ECG parameters, severe ECG abnormality (HR=4.7, p<0.05), right bundle branch block (RBBB; HR=3.9, p<0.05) and bifascicular block (HR=5.8, p<0.05) were significant predictors of sudden death.