Comparison of acute hemodynamic effect of prioritizing ventricular resynchronization vs left ventricular filling during optimization of cardiac resynchronization therapy.

Background: Targeting maximal ventricular resynchronization, with the shortest QRS duration (QRSd), is commonly implemented after cardiac resynchronization therapy (CRT).

Objective: The purpose of this study was to compare optimization of ventricular resynchronization with optimization of left ventricular (LV) filling during CRT by measuring their acute hemodynamic effects.

Methods: Patients with standard CRT indications, recruited from 2 centers, underwent biventricular pacing (BVP) and left bundle branch pacing (LBBP). We performed a within-patient comparison of acute hemodynamic response of systolic blood pressure (SBP) at the atrioventricular delay (AVD) with the shortest QRSd against the AVD with the most efficient LV filling. In a validation substudy, we also performed electrical assessment using QRS area (QRSa) and hemodynamic assessment with the maximum rate of LV pressure rise (dP/dt_max).

Results: Thirty patients (age 65 ± 10 years; 53% male) were recruited. The AVD producing maximal ventricular resynchronization was associated with a significantly shorter QRSd (difference 15 ± 12 ms for BVP and 18 ± 13 ms for LBBP, both P <.01) and a significantly smaller improvement in SBP (difference -3 ± 4 mm Hg for BVP and -2 ± 2 mm Hg for LBBP, both P <.01) compared with the AVD that optimized filling. Similar findings were observed in the substudy, with a significantly smaller improvement in dP/dt_max assessed with QRSd and QRSa (difference -9% ± 7% and -6% ± 4% during BVP, and -5% ± 6% and -3% ± 3% during LBBP, all P <.01).

Conclusion: Targeting the maximal ventricular resynchronization results in suboptimal acute hemodynamic performance with both BVP and LBBP as CRT. These findings support prioritizing LV filling when programming AVD for CRT.