Young Becker Muscular Dystrophy Patients Demonstrate Fibrosis Associated With Abnormal Left Ventricular Ejection Fraction on Cardiac Magnetic Resonance Imaging

ardiomyopathy is the leading cause of mortality in Becker muscular dystrophy (BMD).The variable cardiac phenotype necessitates proactive surveillance.Cardiac magnetic resonance (CMR) is the current gold-standard for functional assessment and identifies early disease progression via late gadolinium enhancement (LGE), a surrogate for myocardial fibrosis.Yilmaz et al, 1 described 15 patients with BMD with median age of 37 years finding 73% with LGE and 53% with abnormal left ventricular ejection fraction (LVEF).The youngest LGE positive (LGE+) patient was 26 years old, although only 4 patients under 25 years were studied.Thus, the adolescent and young adult CMR natural history remain unreported.In this study, we retrospectively reviewed routine CMR exams from 33 genetically confirmed patients with BMD to evaluate the prevalence of myocardial fibrosis and systolic dysfunction.The study was conducted with IRB approval.Deidentified data, methods, and materials will be made available for purposes of reproducing results on reasonable request.Studies were conducted on either a 3 T or 1.5 T magnetic resonance imaging scanner per clinical availability.Cardiac functional imaging was performed using steady-state free precession.LGE was acquired in short axis after administration of 0.2 mmol/kg IV contrast.Gadopentate dimeglumine (Magnevist) was used before 2016 and subsequently Gadobutrol (Gadavist).Notably, these contrast formulations perform comparably at qualitative and quantitative LGE assessment. 2 LGE was quantified as demonstrated in Figure , panel A, from three short axis slices (basal, mid-ventricular, and apical).We chose the Full-Width Half Maximum quantification method per nonischemic cardiomyopathy literature.3 Descriptive analysis is reported as median data with interquartile range (IQR).LGE status was dichotomized as LGE+ or LGE negative(LGE-) and additionally quantified in 10/12 LGE+ patients.The 2 excluded patients had inadequate quality apical slices.Spearman's correlation coefficients were derived to measure association between continuous variables.The median age of the 33 patients was 17.4 years (IQR, 14.7-19.7).Median indexed left ventricular end-diastolic volume (LVEDV i ) was 89 mL/m 2 (IQR, 81-96).Median indexed left ventricular end-systolic volume (LVESV i ) was 40 mL/m 2 (IQR, 33-42).Median LVEF was 57% (IQR, 55-62).Of 33 patients, 12 (36%) were LGE+.When present, LGE was identified within the inferolateral and anterolateral free wall of the left ventricle, variably extending from base to apex in a subepicardial pattern.Of LGE+ patients, 6/12 (50%) had LVEF <55% versus 1/21 LGE-patients.LGE+ patients had a median LVEF 54% (IQR, 48-57) compared with 59% (IQR, 56-63) in LGE-patients.The median age of LGE+ status was 20.5 years (IQR, 18.2-24.3)versus 15.4 years (IQR, 10.9-17.7)for LGE-.The youngest LGE+ patient was 15 years of age.Blinded to