442 Quadripolar LV Lead Provides Phrenic Nerve Stimulation Avoidance

Abstract

Placement of an LV lead is often constrained by phrenic nerve stimulation (PNS). To address the challenge, the Left Ventricular Lead Acute Clinical Study (LILAC) was conducted to evaluate the ability of a new investigational quadripolar LV lead to map the PNS occurrence and mitigate it with single lead insertion at implant using multipolar configurations. This non-randomized study was conducted at 9 international centers and enrolled 54 patients indicated for CRT implantation. The lead design tested was intended to provide electrode contact in two different LV zones simultaneously (mid-apex (MA) and mid-base (MB)). Two lead models with short (S) and long (L) electrode spacing were included to provide the implanter with the ability to select an electrode spacing that matched the patient's individual anatomy. After acquiring a venogram, the implanter tested 1 or 2 lead models by wedging the lead in a selected target vein and recorded the lead testing positions via fluoro images. Unipolar pacing thresholds (PT) and PNS thresholds at each electrode were collected. Fifty patients were tested successfully with additional 2 attempts and 2 intents. The PNS occurrence and threshold are summarized in Table 1. By basing lead selection on individual venograms (no repositioning of the lead), 90% of cases demonstrated that at least one electrode in either zone had a PT ≤ 2.5V without PNS. In addition, 70% of patients achieved dual zone stimulation with a PT of ≤ 2.5V without PNS in MB and MA zones simultaneously. Mean thresholds from the best electrodes in MB and MA zones were 1.7±1.4V vs. 1.6±1.6V (p=ns) accordingly. Of the 24 patients with PNS, electrode switching resulted in no PNS in 20 patients at a PT of ≤ 2.5V and in 23 patients at ≤ 3.5V with unipolar pacing configuration only.Tabled 1 The LILAC quadripolar mapping data suggests PNS mostly occur in MA region with low stimulation threshold compared to MB region. Using this family of quadripolar leads, implanters would be able to achieve low PT and PNS avoidance at either MA or MB zone without repositioning the lead at implant.