Apical left ventricular myocardial dysfunction is an early feature of cardiac involvement in myotonic dystrophy type 1.

INTRODUCTION: Left ventricular (LV) dysfunction is a major prognostic determinant in myotonic dystrophy type 1 (DM1). Therefore, markers of early-stage LV impairment may be useful. The aim of this study was to evaluate 2D echocardiographic LV strain in a cohort of DM1 patients with preserved left ventricular ejection fraction (LVEF) and to compare the results with matched controls. METHODS: This prospective single-center study included 33 consecutive DM1 patients between February 2014 and February 2015. Mean age was 38.2±12.9 years, and 17 (52%) were males. Exclusion criteria were LVEF <55%, QRS >120 milliseconds, history of atrial fibrillation, and presence of a pacemaker with ventricular pacing. DM1 patients were matched to healthy controls according to sex and age. RESULTS: DM1 patients showed significant impairment of global longitudinal strain (GLS) as compared to controls (-18.0±1.9 vs -19.1±2.4; P=.03), characterized by a marked alteration at the apex (-20.0±3.3 vs -22.7±3.1; P<.001). DM1 patients had also global radial strain impairment (20.0±9.8 vs 27.5±14.9; P=.024) compared to controls while global circumferential strain was not statistically different between groups (P=.94). Intra- and inter-observer analysis showed good reproducibility of GLS. CONCLUSION: Despite preserved LVEF, DM1 patients exhibited significantly altered LV GLS, particularly at the apex, as compared with controls. The detection of impaired myocardial deformation at early stages of the disease might help to screen high-risk patients who need closer follow-up.

Left ventricular longitudinal strain impairment predicts cardiovascular events in asymptomatic type 1 myotonic dystrophy.

BACKGROUND: Type 1 myotonic dystrophy (DM1) patients' prognosis is very poor. Up until now, only a few prognostic factors for cardiovascular events have been identified, and they are predictive of end-stage disease. The aim was to assess the prognostic value of global longitudinal strain (GLS) for cardiovascular events in asymptomatic DM1 patients. METHODS: DM1 patients were included between 2011 and 2015 and followed up until January 2016. Patients underwent a transthoracic echocardiography at inclusion. The primary endpoint was a composite of all-cause mortality, type 2 Mobitz 2 and type 3 atrioventricular block, symptomatic sino-atrial block, HV interval≥70ms at invasive electrophysiology exploration, left ventricular ejection fraction (LVEF) ≤45% and newly developed atrial fibrillation. RESULTS: Forty-six patients (25 males, mean age 40years old) were included. The primary outcome was reached in 14 patients with a mean follow-up of 38months. GLS of patients who reached the primary endpoint was significantly impaired as compared to those who did not (-15.1 [-16.7; -12.7] vs. -18.2 [-19.2; -16.7] respectively; P=0.001). According to ROC curve analysis, probability of primary outcome occurrence was significantly greater in patients with GLS values≥-17.2% (P=0.001). On multivariate analysis, PR electrocardiogram interval and GLS remained significantly and independently associated with the primary endpoint [hazard ratio (HR) 1.03, 95% confidence interval (CI) 1.01-1.04, P=0.006 for PR interval; HR 1.4, 95% CI 1.1-1.7, P=0.002 for GLS] while LVEF alone was not. CONCLUSION: Left ventricular GLS is a powerful marker to predict cardiovascular events in asymptomatic DM1 patients, independently of LVEF.