Title: Leadless Pacemakers in Post Operative Patients: Is It Time For
the New to Become the Normal?
Invited Editorial: Manuscript ID JCE-23-0567.R2
Tyler P. Rasmussen, MD, PhD and E. Michael Powers, MD, MBA
University of Iowa Carver College of Medicine
Division of Cariology, Clinical Cardiac Electrophysiology
200 Hawkins Dr.
Iowa City, IA 52242
Edward-powers@uiowa.edu
Merchant et al. describe a single center retrospective analysis of
leadless pacemaker (LP) implant following cardiac surgery or
transcatheter valvular procedures that highlights the performance of LPs
when implanted in patients with atrioventricular block (AVB) and either
high risk features for conventional transvenous pacing or permanent
atrial fibrillation (1). LPs performed well with a limited number of
patients (7%) requiring conversion to transvenous pacing and only a
single procedural complication. However, there was a statistically
significant decline in left ventricular ejection fraction (LVEF) in the
overall cohort. When subgroup analysis was performed, LVEF decline was
only seen in those implanted with VVI devices but not in patients with
VDD devices. Here, we discuss implications of this study.
Transcatheter aortic valve implantation (TAVI) is now more common than
surgical AVR but carries a greater risk of high degree atrioventricular
block (AVB) (~10%) (2,3). Cardiac surgery has been
linked to a 1-3% risk of permanent pacemaker implantation with higher
rates in patients undergoing valve replacement (4). Therefore, the
number of patients at risk for AVB related to cardiac surgery and
catheter-based valve interventions is increasing over time and warrants
a critical evaluation of optimal pacing strategy.
Longitudinal registry data show that Micra (Medtronic, Minneapolis, MN)
LPs have fewer required reinterventions and chronic complications
compared to conventional transvenous pacing systems (5). Furthermore,
mortality is comparable despite being implanted in patients with higher
rates of end stage renal disease (ESRD) and medical complexity (5). LPs
greatly outperform transvenous systems with respect to device related
infections, as the rate of infection in LPs is trivial both short and
long term (5,6). The risk of pacing induced cardiomyopathy (LVEF drop ≥
10%) in pacemaker dependent patients is suggested to be equivalent or
lower in those implanted with an LP (3%) versus those with a
transvenous system (~13%) (7). A major drawback to the
use of LPs is their inability to provide atrial pacing, which typically
limits their use to patients without sinus node dysfunction.
The current paper demonstrates that the use of LPs is a viable strategy
in post-operative patients. Their cohort included 50 patients having
undergone cardiac surgery and 28 with a transcatheter valvular procedure
(1). Of the 28 transcatheter procedures, 25 were TAVI. Factors prompting
an LP implant versus transvenous were permanent AF, ESRD, tricuspid
valve pathology, history of endovascular infection, and dermatological
disease. Mean time from surgery to device implant was 7.3 ± 8.0 days,
which suggests an adequate waiting period for AV conduction recovery in
most circumstances. The only complication in the cohort (1.3%) was an
access site hematoma requiring evacuation. Device parameters were stable
at follow-up with a small but clinically insignificant decline in
impedance and trivial rise in threshold, which is consistent with
previously published data regarding Micra (6). The two major findings
were that the pacing burden declined significantly in the follow-up
period and that there was a significant reduction in the left
ventricular ejection fraction (LVEF) in this cohort. Pacing percentages
fell from mean 75% at implant to mean 48% at follow-up. The reduction
in pacing burden suggests that many patients have late recovery in AV
conduction post procedure. There was a drop in LVEF from baseline
(55.0% ± 10.6%) versus follow-up (51.5% ± 11.2%, p =<
0.001), but this study is not designed to determine if the LVEF drop is
because of the Micra or another unidentifiable factor. Importantly, the
drop in LVEF was significant in the Micra VR group: baseline (54.1% ±
11.9%) versus follow-up (48.8% ± 11.9%, p = 0.003) but not in the
Micra AV group: baseline (56.1 ± 9.0%) versus (54.6% ± 9.7%, p =
0.06). The only patient characteristic that was associated with a
significant drop in LVEF (> 10%) versus those with stable
EF was having a prior history of heart failure with a reduced ejection
fraction. Taken together, this study showed that both Micra AV and VR
can provide safe RV pacing in post-operative patients with a small, but
significant risk for LVEF reduction that is likely linked to right
ventricular pacing.