Background: Cardiomyopathy is the leading cause of mortality for Becker Muscular Dystrophy (BMD).Risk stratification is challenging due to the wide variation of cardiomyopathy onset, progression, and severity; with cardiomyopathy developing independent of skeletal myopathy progression. Current guidelines recommend “complete cardiac evaluation” at ten years of age, but do not specify the type of imaging modality. We have been performing cardiac magnetic resonance imaging (CMR) routinely by 10 years of age. We sought to determine the progression of BMD cardiomyopathy during the adolescent years among patients who have evidence of fibrosis by late gadolinium enhancement(LGE).
Methods: At our center, all BMD patients undergo CMR when sedation is no longer necessary by age 10 years. We retrospectively reviewed the CMR studies performed between June 2013 and June 2018. Statistical analysis was performed using Student’s t-test.
Results: There were 43 BMD patients who underwent 98 CMR studies with LGE assessment. The average age of the first CMR study was 15.5±4.8 (range 7-25) years. Of these 27/43 (63%) patients had negative LGE and 14/43 (33%) had positive LGE on the first study. The LGE positive group was significantly older (p<0.001) with average age 19.5±3.1 years (range 16-25 years) compared to 13.5±4 years (range 7-22 years). Patients who were LGE positive had a lower mean LVEF compared with LGE negative patients (53.9±11.7% vs 62.6±5.3% p-value < 0.005). 31 patients had serial studies for a total of 72 CMR studies. Of the LGE negative patients 2/27 (7%) became positive over a 12 month period. In serial follow up, LGE positive patients showed a statistically significant decline in LVEF. Over an interval of 2.6± 1.7 years, LGE positive patients had a decline in LVEF from 53.9±11.7% to 48.5 ± 10.9 % (p- value < 0.005), and an increase in LVEDVi from 91±30 to 98 ± 30 (p- value < 0.05).
Conclusions: Our study demonstrates a large number of BMD patients with cardiomyopathy identified by LGE at a younger age than previously described. Serial studies demonstrated a significant decline in LVEF and increase in LVEDVi over an interval of 2.6± 1.7 years. CMR studies should be considered in BMD patients when sedation is no longer required. Escalation of medical therapy should be considered for patients who demonstrate evidence of fibrosis. Larger longitudinal studies should be considered determine independent risk factors of cardiomyopathy progression.