Abstract 2513: Optimization Of CRT Timing By Fusion In ECG Lead V1 Is Associated With A Higher Increase In Left-Ventricular Contractility
Introduction: Optimization of CRT timing can result in improvement in cardiac function and long-term clinical outcome in CRT patients. Previous studies in LBBB canines have shown that the maximal improvement in left-ventricular (LV) contractility (LV dP/dt max) is achieved when electrical fusion between intrinsic and LV pace-induced activation is achieved. We hypothesized that optimal timing of the LV pacing pulse can be predicted using surface ECG.
Methods: After implantation of CRT-D devices ten patients underwent LV catheterization with Millar pressure catheter. The CRT-D device was programmed to atrial pacing (AP, baseline) at a rate 10% above the patient’s intrinsic heart rate. LV Only pacing was then applied at different offsets (VVeff) from the intrinsic right-ventricular (RV) sense event (from 150 ms before RV sense (LV150) to 60 ms after (RV60), steps of 30ms). The magnitudes of the peak (QRSp) and nadir (QRSn) of the QRS complex in lead V1 as well as QRS width from 12 ECG leads were determined for each VVeff. Fusion VVeff was defined as the one at which QRSp was closest to QRSn.
Results: LV dP/dt max corresponding to optimization of VVeff by fusion in V1 (895 ± 200 mmHg/s) was higher than that corresponding to
optimization by narrowest QRS (847 ± 222 mmHg/s, p = 0.008),
fixed VVeff = LV60 ms (855 ± 191 mmHg/s, p = 0.04),
fixed VVeff = LV30 ms (837 ± 251 mmHg/s, p = 0.07) or
atrial pacing (757 ± 198 mmHg/s, p < 0.001).
VVeff corresponding to the narrowest QRS (124 ± 22 ms vs 152 ± 17 ms at baseline, p < 0.001) was on average 57 ± 38 ms shorter than that corresponding to fusion in V1.
Conclusions: Optimization of CRT timing by fusion in ECG lead V1 is superior to optimization by narrowest QRS.