DMD/BMD – OUTCOME MEASURES: EP.129 Value of global longitudinal strain for identification and monitoring of left ventricular dysfunction in Becker muscular dystrophy

Abstract

Cardiac involvement is the main cause of death in Becker muscular dystrophy (BMD). Identification of left ventricular (LV) function is crucial, but standard echocardiographic measures such as LV ejection fraction (EF) might not be sensitive enough to detect early myocardial dysfunction. We explored the value of LV global longitudinal strain (GLS) as a more accurate echocardiographic parameter to detect and monitor LV dysfunction in BMD. Furthermore, we studied possible factors associated with LV dysfunction and progression. 40 BMD patients (age 39.0±13.2 years) and 21 matched controls were included. Clinical variables, pulmonary tests, serum biomarkers, and echocardiograms were collected at baseline and after two years. LV systolic function was assessed by LVEF and LV GLS; a significant progression in LV dysfunction was defined as an absolute LV GLS decline ≥15%. Responsiveness to cardiac disease progression was determined using standardized response means (SRM). BMD patients showed impaired LVEF and LV GLS as compared to controls (p<0.001). Of interest, 31 patients (77.5%) showed impaired LV GLS (defined as>-18%) while only 24 patients (60%) had reduced LVEF. LV GLS and LVEF correlated with troponin-I and NT-proBNP (0.52<rho≤0.68), but not with skeletal muscle or pulmonary function. At follow-up (2.0±0.5 years, n=29), LV GLS worsened significantly (-1.3±0.8%, p=0.002, SRM=0.70, annually 0.60%) while LVEF remained stable. No risk factors for LV dysfunction progression were identified. In BMD, LV GLS is frequently impaired and shows deterioration over time as compared to LVEF. LV GLS could be used as a more sensitive parameter to identify and monitor LV dysfunction.