INTRODUCTION
Permanent pacemaker implantation is the only established treatment for
bradyarrhythmia that contributes to improved life prognosis as well as
quality of life. In the last 10 years, 50,000 implantable pacemakers
have been introduced in Japan every year, and more than 60,000 cases
have been recorded annually in recent years. In the United States, more
than 350,000 pacemakers are implanted annually, and this number has
doubled in the last 30 years.1 Elderly people are more
prone to bradyarrhythmias, and it is estimated that more patients will
need more pacemaker implants as the aging society advances. On the other
hand, it has been reported that lead trouble and subcutaneous pocket
complications, which are complications of conventional transvenous
pacemakers, are present in 7% and 11% of cases at 5 years after
implantation, respectively.2 The introduction of
transcatheter pacing systems (TPSs) was expected to reduce lead and
pocket complications. In previous studies, the TPS was shown to be an
effective and safer option, reducing the common complications from
conventional pacemakers and providing a more stable pacing
threshold.3-6 However, some cases require a higher
pacing threshold, because the latter increases post-implantation, which
subsequently decreases battery longevity and increases the risk of an
adverse heart event due to pacing issues. Predictors that require
long-term high pacing thresholds have been reported,6but the cause of increased thresholds after implantation has not been
clarified. Most of the rapid increases in pacing threshold occurred
within one month of implantation, but there were few cases where the
threshold was increased in the medium-to-long term.7-9Therefore, we hypothesized that it would be possible to obtain a stable
pacing threshold in the long term if the increase could be avoided in
the short term.
In this study, we investigated the clinical significance of early
increased pacing threshold by comparing patient background
characteristics, procedure-related indications, and threshold
transition.