Background: His bundle pacing (HBP) is rapidly growing in popularity as an alternative to right ventricular (RV) pacing. One major disadvantage of HBP is the high capture threshold. Achieving optimal His-bundle (HB) pacing location is technically challenging. Suboptimal location often requires a higher pacing stimulus voltage and pulse-widths are also frequently extended to 1.0 ms. Both has a negative impact on the device longevity. This could then lead to more generator changes, as associated with an increased risk of infection and other complications leading to an increased cost to the NHS. There have been no long-term studies, specifically looking at temporal changes of HBP thresholds and the impact this may have on the battery longevity.
Method: 50 consecutive patients were included in this retrospective study, all of whom a Medtronic 3830–69 cm – His lead. [one sentence on patient indication]. All patients received a Medtronic Azure pacemaker. The mean age was 74.6 years and 79% were male. Pacing thresholds were collected during implant, at the 2-week device check, at the 6-month and 12-month follow up – as per departmental protocol. The trends were then analysed.
Results: Pacing threshold were initially high (see Table 1) and continuously decreased throughout the one-year follow-up.
Follow Up Mean Threshold [n=50] Longevity [n=50]
At implant 3.5v @ 1.0ms
3.3 ± 0.6 years
At 2-week device check 2.5V @ 1.0ms 3.5 ± 0.8 years
At 6 month device check 0.5V @ 1.0ms 8.5 ± 1.2 years
At 12 month device check 0.5V @ 1.0ms 7.9 ± 1.1 years
Conclusion: Though the initial threshold in HBP is high at implant – this data shows it decreases over time thus improving longevity. Thresholds appear stable once it passes the 6-month follow up. This positive find should help encourage more His implants. Larger studies are needed to confirm these results. Implant related trauma causes initial rise in HBP threshold. Is there room for improvement on implant practice, leads, dexamethasone, objective assessment of damage (assessing the injury potential).