Predictive value of myocardial delayed enhancement in Duchenne muscular dystrophy

Abstract

In other cardiomyopathies, cardiac magnetic resonance imaging (CMR)-derived myocardial delayed enhancement (MDE), a marker of myocardial fibrosis, is a risk factor for sudden cardiac death (SCD). In Duchenne muscular dystrophy (DMD), the prognostic value of MDE for ventricular arrhythmias and death is unknown. This study aimed to evaluate associations between MDE and electrocardiographic (ECG) changes, ventricular remodeling, risk of arrhythmias, and death in DMD. This retrospective study included all subjects with DMD who had undergone a CMR between January 2006 and December 2011 and had available ECG and 24-h Holter records from the same period. Left ventricular (LV) MDE was semiquantitatively graded from 0 to 4. Comparisons of demographic and clinical characteristics between MDE and no-MDE groups were made. Cox regression analysis was performed to assess factors associated with death. This study investigated 32 boys with a median age of 13.8 years (range, 7.2-17.4 years) and found MDE present in 25 (78 %) of the boys. Compared with the no-MDE subjects, the MDE subjects were older (15.7 ± 3.3 vs 12.1 ± 4.8 years) and had a wider QT dispersion (QTd: 74 ± 30 vs 55 ± 33 ms), a higher incidence of ventricular tachycardia (40 vs 0 %), a lower LV ejection fraction (46 ± 12 vs 56 ± 9 %), a larger LV end-diastolic volume (124 ± 58 vs 68 ± 14 ml/m(2)), and a larger end-systolic volume (57 ± 29 vs 28 ± 10 ml/m(2)) (p < 0.05 for all). During the study period, six of the subjects (19 %) died. The factors associated with mortality were increased age, advanced grade of MDE, higher LV end-systolic volume, lower LV ejection fraction, use of beta-blockers, and ventricular tachycardia. Myocardial fibrosis detected by CMR is an independent predictor of adverse cardiac remodeling, ventricular arrhythmias, and death in DMD. Cardiac MRI using MDE can be applied as a screening tool to detect patients at risk for ventricular arrhythmias, more advanced disease, adverse LV remodeling, and death.