Résumé :
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BackgroundDuchenne muscular dystrophy (DMD) is an inherited myogenic disorder due to mutations in the dystrophin gene on chromosome Xp21.1. It is characterised by progressive muscle wasting and weakness of variable distribution and severity. Heart is involved leading to heart failure. Despite cardiac medical management, prognostic remains poor because of heart degradation. Systolic dyssynchrony is potentially a marker for disease severity and may act as a prognosticator. Moreover, cardiac resynchronization therapy by multisite biventricular pacing presents an additive therapeutic option in the treatment of severe congestive heart failure (EF<35%) with signs of ventricular dyssynchrony (QRS width >120 ms) and who remain symptomatic (NYHA IIIIV) despite optimal medical treatment. Few datas are available about systolic dyssynchrony in DMD. We sought to assess the prevalence of left ventricular dysfunction and systolic asynchrony in patients referred in our unit.Materials and methodsWe performed electrocardiography and echocardiography for adult's patients with genetically proven Duchenne disease, referred in our unit. Conventional 2D echocardiography was performed completed by tissular Doppler imaging. The following parameters were evaluated: LV end-diastolic diameter (LVDD), ejection fraction (EF) assessed by Simpson's equation using the apical four-chamber view, ventricular electromecanical delay. The intraventricular delay was examined by spectral pulsed TDI in the apical 4- and 2-chamber views to delineate the LV long-axis motion. The time to the onset of ejection phase contraction in the systolic wave was measured from the basal segments of septal, lateral, anterior, and inferior walls The interventricular electromechanical delay was calculated as the time difference between the aortic and pulmonary pre-ejection time intervals where aortic and pulmonary ejection flows were recorded in the five-chamber apical and parasternal views, respectively . The intraventricular asynchrony was calculated as the difference between the systolic electromecanical delay of the lateral free wall of the left ventricular and the systolic electromecanical delay of the septal annulus. A systolic delay > 50 ms was considered significant for intraventricular asynchrony. An Interventricular electromecanical delay > 40ms was considered significant for interventricular asynchrony ResultsA total of 48 patients were included in our study. Age ranged from 20 to 37 years with a mean of 28 years. All subjects were disabled and confined to wheeling chair. QRS delay was > 120ms in 10 patients/48 with a QRS delay>150ms in 1 patient. All patients had reduced left ventricular ejection fraction (EF) (mean EF = 43, 3%). 23% of patients had EF below 35%. Mean left ventricular telediastolic diameter was 30mm/m2. 14% of patients had systolic interventricular asynchrony with a high prevalence in patients with low EF<35% (11, 9% in patients with EF< 35% vs 2, 6% in patients with EF>35%). 8% of patients had systolic intraventricular asynchrony with a prevalence of 6% in patients with EF<35%. ConclusionWe found a high prevalence of left ventricular dysfunction in Duchenne muscular dystrophy. Systolic ventricular asynchrony seems frequent particularly in patients with EF<35%. Proposing resynchronisation therapy has to be discussed for selective patients.
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