Introduction: Cardiac resynchronization therapy (CRT) using quadripolar left ventricular (LV) leads provides more pacing vectors compared to bipolar leads. This may avoid phrenic nerve stimulation (PNS) and allow optimal lead placement to maximise biventricular pacing. However, a long-term improvement in patient outcome has yet to be demonstrated.
Methods: Consecutive patients with conventional CRT criteria implanted with quadripolar (n=294) or bipolar (n=652) LV leads were enrolled into a registry at a tertiary London cardiac centre. Lead performance and mortality was analysed over a 5-year period.
Results: Patients receiving a quadripolar lead were younger (68±10 v’s 69±13 years, p=0.10), more were female (16% v’s 12%, p=0.07) and had ischaemic heart disease (48% v’s 43%, p=0.02) compared to patients receiving a bipolar lead. Lead threshold, impedance and procedural radiation dose were significantly lower in those receiving a quadripolar lead (p<0.001). Both groups had similar rates of procedural success but PNS was more common with quadripolar leads (16% v’s 6%, p<0.001). Of these episodes, 96% were eliminated by switching pacing vector with the quadripolar lead compared to only 68% in the bipolar group (p<0.001). Frequencies of lead displacement, wound infection and re-intervention were similar. Patients with a CRT defibrillator had a significantly lower mortality if implanted with a quadripolar compared to bipolar lead (15% v’s 30%, p<0.001).
Conclusions: The use of quadripolar LV leads for CRT enables near elimination of PNS and is associated with a significant reduction in overall mortality. This has important implications for LV pacing lead choice.
