Safety of upgrades for patients with PICM
Vijayaraman et al demonstrated that the HBP threshold could remain
relatively stable after 2 years of follow-up [8]. A recent
publication confirmed this finding in a larger sample and showed over
90% of patients have a capture threshold less than 2.5V @ 1ms after a
median follow-up of 3 years [16]. In 2 patients failed with HBP, we
were not able to capture the distal His-Purkinje system even at high
output. In the prior reported by Vijayaraman et al [9], the
successful rate of HBP upgrade was 95% (57/60) in western population
with AV block. These finding suggest that the progression of conduction
dysfunction was extremely rare even in PICM patients. These results
extend the long-term data about the threshold for HBP. According to our
results, the threshold for HBP was not significant higher after the more
than 12-month follow-up period. Device malfunction, lead perforation and
embolization were not found during follow-up. The technical challenges
in HBP are highly dependent on the operators’ experience [17-19].
Although the results presented are favorable, there are some limitations
in the present study. First, HBP was conducted by experienced
implanters, and there were high success rates in our study along with
potential patient selection bias. Second, the present study focused on
PICM patients with reduced LVEFs. PICM patients with preserved LVEFs may
have unique pathological progress and deserve more clinical assessment.
Third, long-term pacing performance of the his pacing lead and the
potential risks of lead extractions need further careful evaluation.