Abstract 16153: Interval Between QRS Onset to End of the R-Wave in Left Chest Leads Reflects the Left Ventricular Activation Delay -Evaluations of 12-Lead Electrocardiogram and Coronary Sinus Bipolar Electrogram-
Background: Delayed activation of the left ventricle (LV) is thought to be an important factor relating with response to cardiac resynchronization therapy. Our objective was to test the hypothesis that an interval between QRS onset to end of the R-wave (QR) in left chest leads may reflect the LV activation delay.
Methods: We studied 115 arrhythmia patients (67±12 years, 87 males) received electrophysiological testing and evaluated coronary sinus (CS) bipolar electrogram. Patients with right axis deviation (120 to 270 degree) were excluded. Eighteen patients had left bundle branch block (LBBB), 33 with right BBB, 53 with QRS duration <120 ms, and 11 with right ventricular pacing. Interval between QRS onset to major-positive-peak of the V-wave in the CS electrogram was measured and a largest interval was defined as LVI (ms). Location of the electrode indicating LVI was also evaluated. In the 12-lead electrocardiogram, end of the R-wave was determined as an intersection of the descending limb of the R-wave and baseline, and then the average of the QR (ms) was calculated in leads’ set of I-aVL, II-III-aVF, V1-2, V3-4, and V5-6.
Results: LVI ranged from 53 to 195 ms and was correlated with QR in I-aVL (r=0.85, p<0.001) and V5-6 (r=0.57, p<0.001), but no significant correlations were found in other leads. Majority of the patients with normal axis (0 to 90 degree) had LVI in posterior or inferior region of the LV (40/49, 82%). On the other hand, half of the patients with left axis deviation (LAD; -45 to -89 degree) had LVI in anterior or lateral region (26/45, 58%). Significant correlations (p<0.05) were found between LVI and QR in I-aVL (r=0.78), II-III-aVF (r=0.36), and V5-6 (r=0.79) in patients with normal axis, and I-aVL (r=0.88) and V5-6 (r=0.60) in patients with LAD.
Conclusions: Although the region of the latest LV activation was not similar among the patients, Q to R interval in the left chest leads reflected LV activation delay regardless of the differences in QRS duration and morphology.
- © 2013 by American Heart Association, Inc.