176-66: Influence of scar presence and distribution on long-term reverse remodeling by cardiac resynchronization therapy with MultiPoint Pacing

Introduction: Cardiac resynchronization therapy (CRT) with MultiPoint™ Pacing (MPP) improves long-term reverse remodeling compared to conventional biventricular pacing. In this multi-center study, the reverse remodeling benefit of MPP was evaluated with respect to LV scar presence and distribution in patients who underwent scar assessment by delayed enhancement MRI (DE-MRI) prior to device implant. Methods: The transmural extent of scars was quantified for each segment in a 17-segment LV model, with scars ≤25% transmural excluded. CRT-D devices (Quadra Assura MP™ and Quartet™ LV lead, St Jude Medical) were programmed to maximize arterial systolic pressure assessed by a noninvasive hemodynamic system (Finometer MIDI, Finapres Medical Systems). CRT response was defined by echocardiography as >15% reduction in LV end-systolic volume at 6 mo post-implant relative to baseline (ΔESV). Echocardiogram and DE-MRI analyses were performed by blinded core labs. Overall scar distribution throughout the LV was classified as nonexistent (0 scar segments), remote from LV pacing electrodes (nearest scar >3 segments away), and near LV pacing electrodes (nearest scar ≤3 segments away), as registered to DE-MRI by fluoroscopy. Results: Twenty-two pts (68% male, EF 30 ± 7%, QRS 161 ± 21 ms) were enrolled in 4 EU centers and completed DE MRI and 0–6 mo echo evaluations. MPP was programmed in 19/22 pts. Of MPP pts, absolute ΔEF magnitudes, relative ΔESV magnitudes, and relative ΔESV response rates were positive overall, but trended higher for pts with scars (ΔEF = 11.9 ± 5.0%, ΔESV = 33.8 ± 14.0%, N = 12/12 responders) vs. pts with no scars (8.0 ± 6.0%, 22.6 ± 23.0%, N = 4/7 responders). Furthermore, the same values trended higher for pts with one or more scars near LV pacing sites (11.8 ± 5.1%, 35.8 ± 13.2%, N = 9/9 responders) vs. without scars near the pacing sites (9.3 ± 5.9%, 24.1 ± 20.7%, N = 7/10 responders). Conclusions: These results suggest that MPP-enabled CRT with acute hemodynamic optimization improves LV reverse remodeling regardless of scar presence or distribution, but particularly with scar tissue present and with scar tissue proximal to LV pacing sites. These observations highlight the potential of further studies relating the impact of MPP to the underlying scars in BiV non-responders.