Conduction system abnormalities and myocardial dysfunction are observed in patients with myotonic dystrophy type 1 (DM1) and may represent the initial manifestations of the disease.

Some studies have shown improvements of outcomes with use of early cardiac resynchronization therapy (CRT) in DM1 patients. Two-dimensional speckle tracking echocardiography (2D-STE) has recently emerged as a non-invasive biomarker for early detection of dyssynchrony. The aim of this study is to assess a left ventricle (LV) dyssynchrony using 2D-STE analysis in this population.

This is a prospective study, conducted from March 2020 to October 2022 which included DM1 with normal LV ejection fraction (LVEF) and control patients with comprehensive resting echocardiography. Three measures were performed to assess LV mechanical dyssynchrony: opposing-wall delays (longitudinal and radial analyses), modified Yu index, and time to-peak delays of each segment.

Mean age was 23±7years. All three mechanical dyssynchrony criteria were significantly higher in the DM1 group than in healthy subjects: opposing-wall delays in basal inferoseptal to basal anterolateral segments (61.4±45.3msec vs. 18.3±50.4msec, P<0.001, respectively) and in mid inferoseptal to mid anterolateral segments (58.6±35.3msec vs. 42.4±36.4msec, P<0.05, respectively) (Fig. 1), modified Yu index (33.3±10.1msec vs. 28.5±8.1msec, P<0.05, respectively), and most of time-to-peak values, especially in basal and mid anterolateral segments.

The existence of an early LV mechanical dyssynchrony using 2D-STE analysis in DM1 patients before the onset of cardiomyopathy represents a perspective for early prediction of sudden heart death. However, are ICDs really beneficial in terms of improving overall survival, in patients with conduction system disease often presenting more severe forms of myotonic dystrophy itself. Mean corrected time-to-peak delays.