Abstract Body (Do not enter title and authors here): Introduction: Various indicators to detect the most delayed electrical or mechanical activation site of left ventricular (LV) have been studied using intracardiac electrocardiogram or speckle tracking echocardiogram to narrow QRS width in patients with cardiac resynchronization therapy (CRT).
Hypothesis: Unusual intraoperative indicators are required to narrow QRS width in patients with non-LBBB (left bundle branch block) during CRT implantation.
Methods: Nineteen patients (14 men, 71±12yrs, 7 with left bundle branch block: LBBB / 10 non-LBBB / 2 pacing-depend, 6 ischemic cardiomyopathy, LVEF 29.6±8.9%, QRS 152±28ms) underwent CRT implantation. Q-LV (an interval from QRS onset to LV potential), RV-LV (from RV to LV), RVp-LV (from RV pacing to LV), and S-QRS (from LV pacing stimulation to QRS onset) were measured in multi-sites of coronary sinus (CS) veins using a 5 mm spacing 2Fr 8-polar catheters. Q-peak strain (an interval from QRS onset to peak radial strain) was evaluated by speckle tracking echocardiogram in each LV segment during sinus rhythm (SR) and RVp. QRS narrowing was defined as the difference between the QRS interval during SR (or RVp) and the QRS interval with biventricular pacing.
Results: Parameters were evaluated in 17±7 (8-32) sites of 1.9±0.9 (1-4) CS branches in each patient. In LBBB patients, longer Q-LV during SR, extended RV-LV during SR, and lengthy Q-peak strain during SR were associated with QRS narrowing. Shorter S-QRS during LVP and longer RVP-LV during RVP were related to QRS narrowing in non-LBBB patients. (Table)
Conclusion: Suitable indicators depending on QRS morphology are required for QRS narrowing in CRT implantation. The parameters using speckle tracking echocardiogram to detect mechanical LV delay sites might not be useful in patients with non-LBBB.