The role of AV and VV optimization for CRT

Abstract

Cardiac resynchronization therapy is an effective therapy for patients with left ventricular systolic dysfunction and a ventricular conduction delay; however, approximately 30% of patients do not experience significant clinical improvement with this treatment. Modern devices allow individualized programming of the AV delay and VV offset, which offer the possibility of improving clinical response rates with optimized programming. AV and VV delay optimization techniques have included echocardiography, device‐based algorithms, and several other novel noninvasive techniques. While an acute improvement in hemodynamic function has been clearly demonstrated with optimized device settings, long‐term clinical benefit is limited. In the majority of cases, an empiric AV delay with simultaneous biventricular or left ventricular pacing is adequate. The value of optimization of these intervals in “non‐responders” still requires further investigation.

Echocardiographic, Electrocardiographic Changes and Clinical Outcomes of Patients Who Respond to Cardiac Resynchronization Therapy after One Year

“…Optimal ventriculo-ventricular delay may vary over time and repeated CRT optimization would contribute to maintaining the narrowest QRS duration. However, the relationship between CRT optimization and long term prognosis is inconsistent in previously published reports 14)15)16). In our study, although evaluating the accurate effect of CRT optimization on the late response was difficult because of the retrospective design, we generally performed ECG-based optimization in a routine manner in patients showing suboptimal responses.…”

Variation in activation time during bipolar vs extended bipolar left ventricular pacing

“…Twenty‐four hours post‐CRT implant, patients underwent a temporary biventricular endocardial pacing study accompanied by BSM. Iterative echo‐guided optimization of atrioventricular delay and LV and RV (VV) delay was first performed to establish the optimal atrioventricular delay and VV delay for each patient, as previously described . Subsequently, all the available BP and EBP pacing vectors were programmed and tested.…”

Pacing the heart

“…Large VV-delay induced hemodynamic changes have been reported in animal studies 65,66 . However, applied variations in VV-delay (up to 180 ms) were much larger than considered in a clinical setting 59 . Clinical studies have shown a potential benefit for post-procedural VV-delay optimization in a small number of patients 67,68 .…”

“…Optimizing the AV-delay The hemodynamic and clinical benefit of AV-delay optimization remains controversial 59 . Several studies have shown the potential of AV-delay optimization as a strategy to further increase acute hemodynamic response to CRT [60][61][62] .…”

“…The controversy of AV-delay optimization is even more apparent for VV-delay optimization 32,59 . Large VV-delay induced hemodynamic changes have been reported in animal studies 65,66 .…”