Mechanistic insights into the importance of restoring atrioventricular synchrony in dyssynchronous heart failure patients with atrial fibrillation
F De Vere, M Strocchi, T Baptiste, A Lefebvre, N Wijesuriya, S Howell, A Liew, S Niederer, A RinaldiAbstract
Background/Introduction
Atrial fibrillation (AF) is present in up to a third of cardiac resynchronisation therapy (CRT) patients with dyssynchronous heart failure (HF) but relatively underrepresented in CRT literature. Ablation-based management of AF in CRT patients can be in the form of either AF ablation (i.e. rhythm control) or atrioventricular (AV) node ablation (i.e. rate control). Both procedures can restore consistent biventricular pacing (BVP), but only AF ablation enables the restoration of AV synchrony. It is currently unknown which of these approaches leads to superior clinical outcomes in the HF-CRT population. To provide further mechanistic insight, we measured the acute impact of restoring AV synchrony on left ventricular (LV) contractility in HF-CRT patients undergoing AF ablation using invasive LV pressure data.
Purpose
To aid our understanding of the relative importance of restoring AV synchrony in dyssynchronous HF patients with AF, to guide best practice in this population.
Methods
Nine patients with pre-existing CRT for dyssynchronous HF were identified as having low BVP (<95%) secondary to either new onset persistent or high-burden paroxysmal AF. All patients had an atrial lead in situ which could facilitate AV-synchronised pacing. All underwent a clinical AF ablation at the individual operator’s discretion. After clinical ablation, a pressure wire was placed into the LV cavity via transseptal puncture to measure LV dP/dtmax (maximal rate of change in pressure) during different pacing modes, delivered via the patient’s device. Recordings were undertaken for at least 10 seconds during each pacing mode. Each recording was then analysed in retrospect in order to exclude ectopic beats and beats immediately after an ectopic from our analysis.
Results
All 9 patients experienced a greater LV dP/dtmax during AV-synchronised (DDD) BVP vs ventricular only (VVI) BVP (mean difference +7.2%; 95% CI 3.8% to 10.8%; p < 0.01) (see Figure 1). 5/6 also had greater LV contractility in response to DDD right ventricular (RV) pacing vs VVI RV pacing (mean difference +5.1%; 95% CI -0.14% to 10.34%; p = 0.054).
Conclusions
HF-CRT patients saw a significant improvement in LV contractility when switched from VVI BVP to DDD BVP following AF ablation, indicating that restoring AV synchrony has additional acute haemodynamic benefit to restoring BVP alone. This provides supports for the use of a rhythm control strategy over rate control for HF-CRT patients with low BVP secondary to AF.Figure 1 - Visual abstract