5. HBP: Implantation and follow-up
Despite the described difficulties of HBP, there are data from a small
number of centers indeed that show encouraging results for this
implantation technique, as well as for the follow-up of these patients
regarding the variation of the pacing parameters within the time. In a
recently published study including a total of 529 patients, in five
years, with a mean 7-month follow-up, a relatively short learning curve
was recorded, with an overall implant success rate of 81%, which
improved to 87 % after completion of 40 cases.24 The
mean fluoroscopy time was 11.7 ± 12.0 min, and His capture threshold
decreased. HBP lead re-implantation occurred in 7.5% of successful
procedures mainly due to threshold rise. It is worth noting that the QRS
duration decreased by 26 msec in patients with an intrinsic QRS
> 120 msec, while on the contrary, an insignificant
increase in the QRS width by 12 msec observed in the patients with a
narrow QRS.
Regarding the efficacy of HBP, in QRS duration change with non-selective
or selective pacing, in the absence of BBB, selective and non-selective
pacing minimally affected QRS duration, whereas, in the presence of BBB,
QRS duration markedly decreased with both patterns of
HBP.18 AV block morphology seems to affect the
procedural success and needs to be considered before applying this type
of pacing. In a recently published meta-analysis of 1438 patients, the
implant success rate of the lead in the bundle of His averaged 84.8%,
considerably higher than that with older stylet-driven leads with which
the success rate reached up to just 70%. LVEF improved by an average of
5.9% during follow-up and even more in ventricles with impaired
systolic performance <50%, while in preserved LVEFs, no
statistically significant change recorded. Average pacing thresholds
were 1.71 V at implant and 1.79 V at >3 months follow-up,
with various pulse widths.25
Also, according to recently published data, both the intermediate-term
and the long-term performance of HBP leads seem to be quite encouraging
for the implantation success rate and the threshold maintenance.
Nevertheless, threshold increase and the loss of selective pacing have
not been overcome in this study, too, during a follow-up period of 1.5
years, and that may cause a lead revision in rates up to
10%.26 Additionally, in patients’ follow-up data for
five years, HBP proved superior to RV pacing in paced QRS duration and
LVEF improvement with significantly lower rates of occurrence of
Pacing-Induced Cardiomyopathy, findings affecting clinical endpoints,
such as death and heart failure hospitalizations, especially in patients
with >40% ventricular pacing.27 A
summary of published trials conducted in the last 15 years on HBP with
clinical and/or echocardiographic follow-up is included in the 2021 ESC
Guidelines’ supplementary data on cardiac pacing and cardiac
resynchronization therapy.1 Therefore, according to
all mentioned, the question of “when and in which patients” it is
worth applying the HBP could be answered based on the following four
axes, as shown in summary in Figure 4 .