QRS FRAGMENTATION IN DUCHENNE MUSCULAR DYSTROPHY CORRELATES WITH DELAYED ENHANCEMENT AND CARDIAC DYSFUNCTION ON CMR

Presenting Author(s)

• 

  Christopher Schmitt, MD, MPH

  Cardiac Advanced Imaging Fellow
  Nationwide Children's Hospital

Primary Author(s)

• 

  Christopher Schmitt, MD, MPH

  Cardiac Advanced Imaging Fellow
  Nationwide Children's Hospital

Co-Author(s)

• ZP

  Zachary H. Pieters, DO

  Cardiology Fellow
  University of Cincinnati College of Medicine
• KL

  Kathleen Lao, DO

  Physician, Pediatrics
  TriHealth Pediatrics
• RT

  Rachel N. Tonnis

  Pediatric Cardiology Fellow
  Nationwide Children's Hospital and The Ohio State University
• HJ

  Hannah Jacobs, DO

  Advanced Noninvasive Cardiac Imaging Fellow
  Nationwide Children's Hospital
• MG

  Megan Gunsaulus, MD

  Physician, pediatric cardiology
  Nationwide Children's Hospital
• AB

  Amulya Buddhavarapu, MD

  Assistant Professor
  Nationwide Children's Hospital
• EH

  Emily Hayes, MD

  Physician, pediatric cardiology
  Nationwide Children's Hospital
• PW

  Paula Wood, RT

  Advanced Cardiac Imaging Analyst
  Nationwide Children's Hospital
• ML

  Marc Lee, MD

  Assistant Professor of Pediatrics
  Nationwide Children's Hospital
• 

  Kan N. Hor, MD

  Director, Advanced Cardiovascular Imaging and Fellowship Program, Associate Division Chief for Research
  Nationwide Children's Hospital and The Ohio State University

Background: QRS fragmentation on electrocardiogram (ECG) is associated with myocardial fibrosis in ischemic and non-ischemic cardiomyopathy. In Duchenne muscular dystrophy, cardiomyopathy (DMD-CM) is universal, and the primary cause of death. The progression of DMD-CM is variable. Heart failure symptoms are often absent due to loss of ambulation. As such, cardiac magnetic resonance imaging (CMR) is increasingly used in assessing the extent of DMD-CM by assessing the presence of late gadolinium enhancement (LGE) for myocardial fibrosis and ventricular dysfunction by left ventricular ejection fraction (LVEF). Use of CMR can be challenging in this population. We aimed to define the relationship of ECG abnormalities to CMR findings in DMD patient, as ECG can be a sensitive screening test that improves patient selection for CMR.

Methods: This is a single center retrospective study of 195 patients with DMD. Patients who had a CMR which assessed for LGE and LVEF and who had ECGs performed within 6 months were included (Figure 1A-C). QRS fragmentation was determined based on criteria from prior publications, and LGE status was determined to be absent or present. The number of leads with QRS fragmentation was compared between LGE negative and positive groups. QRS fragmentation was also compared between normal (LVEF ≥ 55%) and abnormal (LVEF < 55%) groups with additional analysis based on severity of ventricular dysfunction (normal ≥ 55%; mildly depressed 45-55%; and more than mildly depressed < 45%). Statistical analysis between groups was performed using Student’s t-test with p < 0.05 being significant.

Results: Demographic, ECG, and CMR data is shown on Table 1. QRS fragmentation in a greater number of ECG leads was associated with presence of LGE (2.7±1.3 vs 7.4±2.0, p< 0.0001) and cardiac dysfunction (LVEF < 55%; 4±2.2 vs 8±2.1, p< 0.0001. Within the ventricular dysfunction group, the subgroup with more than mild dysfunction had greater number of leads with QRS fragmentation compared to those with normal, or mild dysfunction (Figure 2A-C).

Conclusion: This is the largest study to correlate functional data (LGE and LVEF) from CMR to fragmented QRS morphology in the DMD patient population. QRS fragmentation on ECG is associated with presence of myocardial fibrosis by LGE and with the extent of ventricular dysfunction by CMR. The presence of QRS fragmentation by ECG should trigger further assessment by CMR and may be an effective screening tool to stratify the use of CMR.

QRS fragmentation is defined as a mid-wave change in the direction of deflection - Fragmentation was defined as R wave notching (A) S wave notching (B) or more complex QRS morphology (C).

Box and Whisker Plot of QRS Fragmentation, LGE and LVEF. (A) QRS fragmentation on ECG is significantly increased in patients with late gadolinium enhancement. (B) Greater number of leads with QRS fragmentation is observed in patients with LV ejection fraction <55% and (C) those with worse ventricular dysfunction.