Left bundle branch block in Duchenne muscular dystrophy: Prevalence, genetic relationship and prognosis

Abstract

Duchenne muscular dystrophy (DMD) is an inherited myogenic disorder due to mutations in the dystrophin gene on chromosome Xp21.1. We designed this study to determine the prevalence of LBBB, whether there is a relationship between LBBB and genetic pattern and to assess predictive factors of acute cardiac events in adult DMD patients. We reviewed the charts of DMD followed at the Home Mechanical Ventilation Unit of the Raymond Poincare University Hospital. A total of 121 patients, aged from 18 years to 41 years were included in our study. Median VC was 12% [7;19.5] of predicted. Almost all patients were on home mechanical ventilation (95%). LBBB was present in 15 patients (13%); among them, 10 disclosed exonic deletions. After a median follow-up of 6 years, 21 patients (17%) experienced acute heart failure (AHF), 7 patients (6%) supraventricular arrhythmia, 3 patients (2.4%) ventricular arrhythmia, 4 patients (3%) significant electrical disturbances. LBBB was significantly associated with cardiac events ( OR = 12.7; 95%CI [3.78–42.7]; P < 0.0001) and mortality ( OR = 4.4; 95%CI [1.44–13.7]; P : 0.009). Presence of residual dystrophin protein was associated with less cardiac events. Age and LVEF are also predictive factors for cardiac events and mortality. LBBB is a major predictive factor of cardiac events in DMD. Presence of residual dystrophin protein seems to be associated with less cardiac events.