Abstract 13287: Electrocardiographic Manifestations of Non-Ischemic Myocardial Fibrosis on Cardiac Magnetic Resonance Imaging
Background: Septal midwall fibrosis (MWF) on CMR has been linked to pro-arrhythmic risk in patients with non-ischemic cardiomyopathy (NICM). Electrophysiologic manifestations of MWF on surface electrocardiography (ECG) are not known.
Methods: The population comprised patients with angiography verified NICM (LVEF ≤ 40%) undergoing CMR and 12 lead ECG within 1 week. ECGs were analyzed quantitatively using automated software; QRS waveform components were measured in all leads, with regional septal activity localized to V1 - V2. Delayed enhancement (DE) CMR was used to identify MWF (hyperenhancement confined to mid myocardial or epicardial aspect of interventricular septum). Cine-CMR was used to quantify LV volume, EF, and myocardial mass.
Results: 108 NICM patients (54±15 yo, 59% male, LVEF 26±9%) underwent CMR and ECG ([[Unable to Display Character: ▵]] 0 ± 3 days): 39% had septal MWF on DE-CMR. Patients with MWF were more likely to be male (71% vs 52%; p = 0.04), but were otherwise clinically similar to those without MWF. On ECG, MWF was associated with altered septal electrical activity, as evidenced by decreased total and intrinsicoid R wave duration (both p = 0.01) in leads V1-V2, despite similar Q and S wave amplitudes and durations (Table ). R wave shortening was independent of MWF pattern, with similar total R wave duration between patients with MWF limited to the epicardium (18 ± 8 msec) vs those with concomitant or isolated mid-septal involvement (18 ± 9 msec; p=0.78). In multivariate analysis, MWF was associated with septal R wave shortening (OR = 1.57 per 10 msec; CI 1.02-2.40; p=0.04) independent of LV end diastolic volume (OR = 1.25 per 10ml/m2; CI 1.09-1.42; p=0.002), mass (OR = 0.89 per 10 gm/m2; CI 0.74-1.08; p=0.23), and male gender (OR = 2.29; CI 0.92-5.65; p=0.07) (model χ2 =24; p<0.001).
Conclusions: In patients with NICM, septal MWF yields localized alterations in electrical activity evident on surface ECG. Localized septal R wave shortening is associated with MWF, independent of gender and LV geometry.
- © 2013 by American Heart Association, Inc.