The Role of the Atrial Electromechanical Delay in Predicting Atrial Fibrillation in Myotonic Dystrophy Type 1 Patients

Myotonic Dystrophy and Atrial Fibrillation Background Paroxysmal atrial tachyarrhythmias frequently occur in myotonic dystrophy type 1 (DM1) patients. The aim of the current study was to evaluate the atrial electromechanical-delay (AEMD) in a DM1-population with normal cardiac function and its relationship to atrial fibrillation (AF) onset. Methods and Results Fifty DM1 patients (28 male; mean age 34.2 ± 11.4 years) and 50 healthy subjects used as controls, matched for age and gender, were studied for the occurrence of atrial fibrillation during a 4-year follow-up, through 30-day external loop recorder (ELR) monitoring performed every 6 months. Intra-AEMD and inter-AEMD of both atrium were measured through tissue-Doppler echocardiography. Compared to the healthy control group, the DM1 group showed a statistically significant increase in inter-AEMD and intraleft-AEMD. Dividing the DM1-group into 2 subgroups (patients with or without AF), the inter-AEMD and intraleft-AEMD were significantly higher in the subgroup with AF compared to the subgroup without AF. A cut off value of 39.2 milliseconds for intraleft-AEMD had a sensitivity of 90% and a specificity of 90% in identifying DM1 patients with AF risk. A cut off value of 57.7 milliseconds for inter-AEMD had a sensitivity of 84.2% and a specificity of 93.5% in identifying this category of patients. Conclusion Our results showed that the echocardiographic atrial electromechanical delay indices (intraleft and inter-AEMD) were significantly increased in DM1 subjects with normal cardiac function. Intraleft and inter-AEMD represent noninvasive, inexpensive, useful and simple parameters to assess the AF risk in DM1 patients.