Abstract 12404: Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy ECG Phenotype is Characterized by Low Amplitude of Spatial QRS Vector, and Small QRS Loop
Background: Low QRS voltages are frequently observed in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). Mechanistically, fibrofatty replacement explains low QRS voltage. Nevertheless, low QRS voltage is viewed as a non-specific finding. However, spatial QRS vector amplitude and QRS loop area have not been studied in ARVD/C.
Methods: We compared ECG characteristics of patients with ARVD/C phenotype (n=98, Johns Hopkins ARVD registry) and controls (n=60, unaffected [not a mutation carriers] family members of a desmosomal gene mutation carriers, or patients with frequent premature ventricular contractions/ventricular tachycardia without structural heart disease). Peak-to-peak QRS voltage was measured on 12-lead ECG in V1-V4 leads. The inverse Dower transformation was applied to construct orthogonal XYZ leads. The peaks of the spatial QRS and T vectors were detected as the furthest points from the origin point in the QRS-loop and T-loop respectively. Mean amplitudes of spatial QRS and T vectors were measured. The areas of the QRS and T loops were calculated on the dynamic main plane using successive triangles along the loop from the peak to the origin point. In addition, results were compared with a previously studied large (n=722) ambulatory heart failure (HF) cohort ( NYHA class II-III, both ischemic and non-ischemic cardiomyopathy).
Results: Mean spatial QRS vector amplitude was significantly smaller in ARVD/C patients, as compared to controls (1.2±0.5 vs. 1.7±0.5 mV; P≤0.0001). Area of QRS loop was half as large in ARVD/C patients [median 54.4 (Interquartile range 30.7-98.1) vs. 108.7 (80.0-148.8) mV2; Wilcoxon rank sum test P≤0.0001]. Similar, but less pronounced differences in spatial T vector amplitude (0.25±0.13 vs. 0.38±0.16 mV; P≤0.0001) and T loop area [8.3 (3.6-13.7) vs. 14.2 (8.1-28.9)mV2; P≤0.0001) were seen. Spatial QRS vector amplitude in the ARVD/C group was below the 10th percentile of spatial QRS vector amplitude measured in the HF population.
Conclusion: QRS voltage in right precordial leads, spatial QRS vector amplitude and QRS loop area diminished in ARVD/C patients, and may be considered as ARVD/C markers. Further study of normalized by body surface area, age, and gender QRS voltage is needed.
- © 2013 by American Heart Association, Inc.