Key result
Programmability of three left ventricular pacing vectors achieved acceptable pacing thresholds and phrenic nerve stimulation margins in 87% of patients, compared to 74% with conventional systems.
Why the study?
Does programmability of three left ventricular pacing vectors improve the identification of acceptable pacing thresholds and margins to phrenic nerve stimulation in patients with CRT-D?
Observational (n=132)
Yes
Does programmability of three left ventricular pacing vectors improve the identification of acceptable pacing thresholds and margins to phrenic nerve stimulation in patients with CRT-D?
Programmability of multiple left ventricular pacing vectors in CRT-D systems significantly increases the likelihood of achieving acceptable pacing thresholds without phrenic nerve stimulation compared to conventional systems.
Answers are grounded in this paper and cite their sources.
May aid LV vector selection in CRT-D; extends observational data but leaves outcome benefits open for randomized trials.
AIMS: Elevated left ventricular (LV) pacing thresholds or phrenic nerve stimulation (PNS) might be possible reasons for absence of continuous and effective biventricular stimulation. This study investigated the benefit and clinical efficacy of the ability to choose one out of three different LV pacing vectors for the management of suboptimal LV pacing thresholds and PNS. METHODS AND RESULTS: This prospective, observational multicentre study enrolled 132 patients (Pts) implanted with a cardiac resynchronization therapy defibrillator, that offers three LV pacing vectors: (i) Bipolar; (ii) LVtip ↔ RVcoil; (iii) LVring ↔ RVcoil (RV = right ventricular). Left ventricular pacing thresholds and PNS thresholds were obtained in sitting and left lateral body position for all programmable LV pacing vectors at hospital discharge and follow up (FU). In 97%, a bipolar transvenous LV lead was successfully implanted. In 87% of Pts at least one acceptable pacing vector could be identified that provides good pacing threshold (≤ 2.5 V at 5 ms) and acceptable margin to PNS (≥ 2:1). This is an increase of 18% compared with conventional bipolar systems (74%) with two LV vectors and of 25% compared with unipolar systems (70%). The LVtip ↔ RVcoil vector provided the best LV pacing thresholds, but the highest rate of PNS. CONCLUSIONS: The programmability of LV pacing vectors is a powerful feature to avoid PNS and obtain acceptable LV pacing thresholds. In order to retain reprogramming options for LV vectors during FU, LV pacing leads with at least two electrodes should be chosen whenever possible.
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Klein et al. (2012) conducted an observational in Cardiac resynchronization therapy defibrillator patients (n=132). Programmability of three LV pacing vectors vs. Conventional bipolar systems (two LV vectors) or unipolar systems was evaluated on Identification of at least one acceptable pacing vector providing good pacing threshold (≤ 2.5 V at 5 ms) and acceptable margin to phrenic nerve stimulation (≥ 2:1). Programmability of three left ventricular pacing vectors achieved acceptable pacing thresholds and phrenic nerve stimulation margins in 87% of patients, compared to 74% with conventional systems.
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