CRT: comparative long-term outcomes of LV-only fusion pacing versus optimized biventricular pacing
A A Faur-Grigori, D D Anutoni, A M Bumbar, M Morenci, L Cirin, B Suciu, C Vacarescu, S Crisan, C T Luca, D C CozmaAbstract
Background
Despite optimized biventricular pacing (BiVp), up to 40% of CRT patients show limited response. LV-only fusion pacing has emerged as a more physiologic alternative, preserving intrinsic right ventricular conduction and improving electromechanical activation in patients with intact atrioventricular (AV) conduction. Long-term comparative data between LV-only fCRTp and optimized BiVp regarding response and clinical outcomes are still limited.
Methods
We retrospectively analyzed 207 CRT patients (mean follow-up 5.0 ± 2.1 years): 120 treated with LV-only fusion pacing and 87 with optimized BiVp. Both pacing strategies were optimized using echocardiographic assessment and surface ECG analysis at rest and during exercise test. All LV-only fusion pacing patients were in sinus rhythm with PRi<250 ms at baseline. Superresponse was defined as a final LVEF ≥45% associated with an absolute increase ≥20 percentage points from baseline and/or a ≥30% reduction in LV end-systolic volume.
Results
At baseline, mean age was 66 ± 9 years in the LV-only group and 67 ± 10 years in the BiVp group, with 64% vs 61% male, mean LVEF was 28 ± 6% in LV-only fusion pacing vs 25 ± 8% in BiVp group; mean QRS duration was 162 ± 17 ms in LV-only fusion pacing group vs 156 ± 18 ms in BiVp, respectively; the incidence of ischemic etiology was 38% in LV-only fusion pacing group at baseline and 46% in BiVp group. In the LV-only fCRTp cohort, 27.5% were CRT-D and 72.5% CRT-P systems, whereas in the BiVp group approximately 55% were CRT-D and 45% CRT-P. LV-only fCRTp resulted in a greater improvement in LVEF (39 ± 10% vs 33 ± 11%) and a threefold higher rate of superresponse (22.8% vs 8.7%, p = 0.001) compared with BiVp. Hospitalizations for atrial fibrillation were less frequent in the LV-only group (10.6%) than in BiVp (24.7%, p=0.04), consistent with a favorable atrial response. In the LV-only fusion pacing, responders showed significant left atrial reverse remodelling (median Δ LAV -6.0 mL vs +12.5 mL in nonresponders, p=0,015). Heart failure-related hospitalizations were significantly lower in the LV-only fusion pacing group (28.5%) compared with BiVp (45.3%, p=0.02). Ventricular arrhythmic events (ventricular tachycardia or electrical storm) occurred in 7.3% of LV-only patients versus 19.8% in the BiVp group (p = 0.03). Furthermore, two LV-only fCRTp patients (1.6%) required ICD upgrade due to sustained VT.
Conclusions
LV-only fusion CRT pacing was associated with superior reverse remodeling, a higher rate of superresponse, and significantly fewer arrhythmic and heart failure–related hospitalizations compared with optimized BiV pacing. Further large-scale comparative studies with long-term follow-up are warranted to confirm these findings and to better define patient selection criteria for LV-only fusion pacing.