January 17, 2011Open Access
View Full PaperLeft ventricular lead implantation at a phrenic stimulation site is safe and effective
Key Result
Left ventricular lead implantation at a phrenic stimulation site using specific threshold criteria was safe, with non-reprogrammable phrenic stimulation occurring in 3.7% of patients vs 1.1% at non-PS sites.
Study Design
Type
Cohort (n=211)
Structured PICO
Is left ventricular lead implantation at a phrenic stimulation site safe and effective in patients undergoing CRT device implantation?
P
Population
211 consecutive patients undergoing cardiac resynchronization therapy device implantation, followed for a mean of 16 months.
E
Exposure
Left ventricular lead implantation at a phrenic stimulation (PS) site (n=27) based on specific criteria (no PS at ≤3.5 V/0.5 ms, LV threshold ≤1.5 V, and a PS/LV threshold ratio >4)
C
Comparator
Left ventricular lead implantation at a non-PS site (n=174)
O
Outcome
Long-term outcomes including changes in phrenic stimulation and left ventricular thresholds, and incidence of non-reprogrammable phrenic stimulationsafety
Implanting a left ventricular lead at a phrenic stimulation site using specific threshold criteria is safe and effective, avoiding the need to abandon otherwise optimal pacing sites.
Main Result
Absolute Event Rate: 3.7% vs 1.1%
Abstract
AIMS: Phrenic stimulation (PS) is a major limiting factor for both left ventricular (LV) lead placement and cardiac resynchronization therapy (CRT) delivery. We have developed a protocol allowing for LV lead implantation at a PS site based on specific criteria regarding phrenic and LV acute capture thresholds. The present study examined long-term outcomes in patients treated using this protocol. METHODS AND RESULTS: A total of 211 consecutive patients underwent CRT device implantation. The procedure was successful in 201 patients. Leads were implanted at a PS site in 27 patients (PS patients) and a non-PS site in 174 patients (non-PS patients). Left ventricular leads were placed at a PS site only on the following conditions: no PS at ≤3.5 V/0.5 ms, LV threshold ≤1.5 V, and a PS/LV threshold ratio >4. The mean PS threshold decreased (5.1 ± 1.6 vs. 2.8 ± 1.6 V, P < 0.001) and the mean LV threshold remained stable (1.0 ± 0.7 vs. 0.9 ± 0.8 V, P = 0.6) in PS patients over the 16 ± 9 month follow-up. Only one PS patient experienced non-reprogrammable PS and required a re-operation. Seven PS patients required very low LV channel output programming without the usual safety margin of twice the LV threshold amplitude or three times the pulse width. However, 100% LV capture was shown in those patients during daily activity. Non-reprogrammable PS occurred in 2 of the 174 non-PS patients. CONCLUSION: Our strategy for LV lead implantation at a PS site was found to result in long-term safe and effective outcomes.