Acute and Long-term Outcomes of quadripolar IS-4 versus bipolar IS-1 Left Ventricular Leads in Cardiac Resynchronization Therapy: A Retrospective Registry Study.

BACKGROUND: The implantation procedure of left ventricular (LV) leads and the management of cardiac resynchronization therapy (CRT) patients can be challenging. The IS-4 standard for CRT offers additional pacing vectors compared to bipolar leads (IS-1). IS-4 leads improve procedural outcome and may also result in lower adverse events during follow-up (FU) and improve clinical outcome in CRT patients. Further long-term FU data comparing the two lead designs are necessary.

METHODS: In this retrospective, single-center study we included adult patients implanted with a CRT-Defibrillator (CRT-D) or CRT-Pacemaker (CRT-P) with a quadripolar (IS-4 group) or bipolar (IS-1 group) LV lead and with available ≥3 years clinical FU. The combined primary endpoint was a combination of predefined, lead-related adverse events. Secondary endpoints were all single components of the primary endpoint.

RESULTS: Overall, 133 patients (IS-4 n = 66; IS-1 n = 67) with a mean FU of 4.03±1.93 years were included. Lead-related adverse events were less frequent in patients with an IS-4 lead than with an IS-1 lead (n = 8, 12.1% vs. n = 23, 34.3%; p = 0.002). The secondary outcomes showed a lower rate of LV lead deactivation/explantation and LV lead dislodgement/dysfunction (4.5% vs 22.4%; p = 0.003; 4.5% vs. 17.9%; p = 0.015, respectively) in the IS-4 patient group. Less patients suffered from unresolved phrenic nerve stimulation with an IS-4 lead (3.0% vs. 13.4%; p = 0.029). LV lead-related re-interventions were fewer in case of an IS-4 lead (6.1% vs. 17.9%; p = 0.036).

CONCLUSION: In this retrospective analysis, the IS-4 LV lead is associated with lower lead-related complication rates than the IS-1 lead at long-term FU. This article is protected by copyright. All rights reserved.