Single lead ventricular pacing from the right atrium: acute electrical results from the VFAHF clinical study

Background

Biventricular (BiV) pacing requires the placement of transvenous pacing leads into the coronary sinus and right ventricle, which requires crossing of the tricuspid valve to achieve resynchronization.

Purpose

This study evaluated the acute feasibility and safety of pacing the ventricle from the right atrium (VFA) by implanting a single, bipolar pacing lead through the Triangle of Koch (ToK) into the atrioventricular septum in patients with heart failure (HF) indicated for cardiac resynchronization therapy (CRT).

Methods

Patients in the prospective, multicenter VFAHF (Ventricle from Atria Heart Failure) study were temporarily implanted with the investigational VFA lead, followed by a permanent CRT implant. The primary objectives were to assess the success of ventricular pacing and the absence of complications related to the VFA implant procedure through 1-month follow-up. Acute resynchronization was evaluated using QRS duration from 12-lead ECG and an ECG surface mapping system (ECG Belt, Medtronic) designed to assess ventricular electrical dyssynchrony (SDAT).

Results

Ventricular pacing capture was achieved in 25/29 patients (86%). Of the 25 patients with a successful VFA implant, 23 (92%) had at least 1 implant with left ventricular capture. In the 3 patients with multiple successful implants, the additional implant did not differ in type of ventricular capture from the first successful implant. The 3 VFA implants adjudicated as a right ventricular capture were in 2 patients with interventricular conduction delay (IVCD).

The QRS duration during QRS duration-optimized VFA pacing was 155 ± 31 ms. This was a significant reduction in duration compared to intrinsic (178 ± 32 ms, p = 0.0001), RV only pacing (196 ± 34 ms, p<0.0001), and LV only pacing (171 ±44, p=0.003). VFA and BiV QRS durations were not significantly different (p=0.26). The paced settings optimized for QRS duration additionally showed benefit via surface activation metrics. QRS duration-optimized VFA and BiV pacing both significantly reduced SDAT compared to intrinsic (p=0.0003 vs. VFA, p=0.005 vs. BiV) and RV only pacing (p=0.002 vs. VFA, p=0.02 vs. BiV).

Conclusions

While this data was acute and limited to surface electrode activation assessment, the results indicate that the benefit of VFA pacing extends beyond the ability to pace the ventricles without crossing the tricuspid valve and includes the potential for beneficial electrical synchrony in dyssynchronous patients. The ability to pace the ventricles from the atrium presents additional opportunity for development of therapy for pacemaker indicated patients, particularly in the context of leadless pacing evolution.Acute electrical data