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Does Myocardial Delayed Enhancement Predict Sudden Cardiac Death Risk In Duchenne Muscular Dystrophy?

Friday, October 19, 2012: 9:00 AM
Room 275-277 (Morial Convention Center)
Shaji C. Menon, MD1, Kirk N. Liesemer, MD2, Tyler Bardsley3, Mason C. Heywood1, Richard V. Williams, MD1, Michael D. Puchalski, MD1 and Susan P. Etheridge, MD3, (1)Pediatric Cardiology, University of Utah, Salt Lake City, UT, (2)Cardiology, Primary Children's Medical Center, Salt Lake City, UT, (3)Pediatrics, University of Utah, Salt Lake City, UT

Purpose: Heart failure secondary to myocardial fibrosis is a common cause of mortality in Duchenne muscular dystrophy (DMD). In other cardiomyopathies, cardiac MRI (CMR) derived myocardial delayed enhancement (MDE) is a risk factor for sudden cardiac death (SCD). In DMD, the prognostic values of MDE in predicting ventricular arrhythmias, ECG changes and SCD is unknown. The purpose of this study was to evaluate an association between MDE and ECG changes, risk of arrhythmias and death in DMD.

Methods: In this retrospective study, we included all subjects with DMD who had undergone a CMR within the last 5 years and had ECG’s and 24-hr Holter records from the same period.  Data collected included: age, left ventricular end-diastolic volume (LVEDV), and LV ejection fraction (LVEF), as well as the presence, location and extent of MDE. LV MDE was graded as: 0: no MDE, 1: 1/3 of basal LV free wall, 2: 2/3 of basal LV free wall, 3: entire LV free wall and 4: LV free wall and septum. ECG and Holter were analyzed for corrected QTC, QT dispersion (QTd), frequent premature ventricular contractions (≥ 6 PVCs/hour), non-sustained and sustained ventricular tachycardia (VT). Comparisons of demographic and clinical characteristics between MDE and no MDE groups including grades of MDE were made with the Wilcoxon-Mann-Whitney and Kruskall Wallis tests for continuous data and the Fisher’s exact test for categorical data. Regression analysis was performed to assess associations between MDE and LVEDV and LVEF, ECG changes, arrhythmias and death.

Results: A total of 32 patients (all males) with median age 13.8 years (range 7.2-17.4 years) were studied. MDE was present in 25 (78%) {grade: N (%) = 1:13 (40%), 2:4 (13%), 3:3 9%), and 4: 5 (16%)}. The mean LVEF and LVEDV between no MDE and MDE groups were 56±9% vs. 46±12% (p=0.04) and 124± 58ml vs. 68±8ml (p=0.02) respectively. The incidence of frequent PVCs and VT between MDE and no MDE groups were 65% vs. 0% (p=0.06) and 41% vs. 0% (p=0.05) respectively. There were 6 deaths, all secondary to cardiac causes and all had MDE. On univariate regression analysis, the degree of MDE was associated positively with QTC (p =0.023), QTd (p= 0.096), LVEDV (p= 0.03), and negatively with LVEF (p= 0.007), frequent PVCs (p= 0.004), presence of VT (p= 0.002), and mortality (p=0.03). On multivariate analysis, grade of delayed enhancement was independently associated with increased LVEDV (OR=1.03, p= 0.06), frequent PVCs (HR=16.5, p= 0.015) and VT (OR=27.3, p= 0.017).

Conclusion: Cardiac fibrosis detected by CMR is an independent predictor of adverse outcome in DMD.  As a novel marker it seems to detect those at risk of SCD and more advanced disease. In DMD, MDE might guide specific therapies for ventricular arrhythmias and SCD prevention.