Left ventricular lead implantation at a phrenic stimulation site is safe and effective

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.