Kathleen Lao, BS; Jeffrey S Bennett, MD, PhD; Anna N Kamp, MD, MPH; William Hor, BS; Kan N Hor, MD.
Background: Duchenne muscular dystrophy (DMD) is an X-linked results in dystrophin deficiency and universally develop cardiomyopathy and early mortality. Subepicardial myocardial fibrosis (MF) by late gadolinium enhancement (LGE) precedes decline in left ventricular ejection fraction (LVEF) by cardiac magnetic resonance imaging (CMR) determines therapy. The use of CMR is not universal due to concern of cost and availability. Electrocardiographic abnormalities is common in DMD but has not been linked to extent of disease. ECG axis deviation, right (RAD) and left (LAD) is associated with anterolateral and inferior myocardial infarction leading to MF but this relationship has not been studied in DMD. We hypothesized that QRS axis deviation (RAD and LAD) is associated MF and abnormal LVEF in DMD patients as the MF occurs in the same segmental distribution.
Methods: Retrospective review of DMD patients with CMR with LGE with MF and ECG axis within 6 months was recorded. Group A patients had no LGE and Group B had LGE. Normal axis is define as -30 to 90 degrees, QRS axis was compared between the two groups. Statistical analysis was performed using the Student’s t-test.
Results: 325 patients met criteria, Group A (n = 174) patients were younger and had normal LVEF (62.7±5.8) with 9/174 (5%) having LVEF <55% while Group B (n = 151) had lower LVEF (53.8±11, p < 0.0001) with 70/151 (46%) with LVEF<55%. The mean axis of both group was normal with 7/174 (4%) in Group A and 36/151 (23.8%) in Group B had abnormal axis. The 2 patients in Group A with significant axis deviation had abnormal LVEF. In Group B patients with LGE but preserved LVEF 14/82 (17%) compared to 22/69 (31.9%) had abnormal axis.
Conclusion: This is the first study to correlated QRS axis with MF and LVEF findings in a large cohort of DMD patients. CMR for MF and LVEF assessment is used to determine medical regimens in DMD patients. However, CMR is not universally available and expensive and the use of ECG is important to screen for at risk patients. Our study demonstrate that QRS axis deviation is associated MF and LVEF and can be an affective screening tool.
To understand that in disease like Duchenne muscular dystrophy, traditional heart failure symptoms are lacking and the use of cardiac MRI is vital in diagnosing and stratify disease. The use of screening ECG for QRS axis deviation can help id