Introduction and Background:
Tricuspid regurgitation (TR) is a common valvular abnormality associated
with cardiovascular morbidity and mortality[1-3]. Many patients with
tricuspid regurgitation present for intervention with advanced disease,
often after conservative medical management with diuretics and treatment
of other cardiac co-morbidities as retrospective studies have failed to
reveal a significant benefit in surgical treatment over medical
management for isolated tricuspid regurgitation[4]. However, this
delay can increase the surgical risk at the eventual time of
intervention[5]. Transcatheter tricuspid valve placement has become
a novel approach to address the clinical needs of these patients with
initial approaches focusing on valve repair and more recent
interventions focusing on valve replacement[6]. The EVOQUE® valve
replacement system (Edwards Lifesciences, Irvine, CA) was originally
described for percutaneous mitral intervention and subsequently adapted
for percutaneous tricuspid intervention (EVOQUE TTVR)[7, 8].
Recently, a multicenter, observational, first-in-human study using the
EVOQUE valve for severe TR demonstrated high technical success,
acceptable safety and significant clinical improvement. In this series
two of twenty-five patients (8%), subsequently required pacemaker
implantation. This value appears in range with large, published cohort
data for surgical tricuspid intervention, which revealed a need for
pacemaker implantation in 5.2% of patients with tricuspid repair and
14.2% of patients with tricuspid replacement[7]. In the TRISCEND
early feasibility study of the EVOQUE TTVR, of 132 patients (presented
at the 2021 TCT Congress), 10.5% required a new pacemaker
implant[9].
We present three cases of leadless pacemaker implantation following
EVOQUE TTVR. Leadless pacemaker implantation has been reported following
valve-in-valve transcatheter tricuspid valve intervention[10].
However, this case used a much less imposing valve. Our case series
demonstrates the feasibility of leadless pacemaker placement following
TTVR with the EVOQUE valve.
The EVOQUE valve replacement system utilizes a 28Fr delivery catheter,
the prosthesis consists of a self-expanding Nitinol frame with bovine
pericardial leaflets, an intra-annular sealing skirt, and ventricular
anchors. The valve is available in three sizes: 44mm, 48mm, and 52mm
chosen based on annular dimensions from transesophageal echocardiography
(TEE) and cross-sectional CT rendering. Valve deployment is performed
with direct 2D and 3D visualization from transesophageal
echocardiography. Expansion of the valve along the tricuspid annulus is
first achieved by unsheathing the 9 ventricular anchors and confirming
their position beneath the leaflet segments. The atrial inflow portion
of the valve is then exposed at the annular level with subsequent valve
expansion and deployment. By its nature, the valve applies direct
pressure on the basal septum of the right ventricle and potentially the
triangle of Koch meaning that both the bundle of His and the compact AV
node may be subject to injury. The long term safety of placing
transvenous leads across this valve is unknown, and we have concerns
about the potential for interaction with the lead’s insulation given the
complex Nitinol structure and ventricular anchoring mechanism of the
prosthesis. Likewise, this valve is an imposing structure and our
preconceived notion was that placement of a leadless pacemaker across it
may be difficult. See figure 1a.
Given these concerns, and due to other patient factors, we chose to
implant Micra® (Medtronic, Minneapolis, MN) leadless pacemakers in three
patients undergoing EVOQUE TTVR. Our primary experience with leadless
pacing has been with the Micra transcatheter pacing system and the
safety and efficacy of these devices has been extensively
studied[11-14]. The Micra is available in two forms: Micra VR and
Micra AV, with the latter having the ability to incorporate mechanical
atrial sensing algorithms to provide AV synchronous pacing[15]. The
Micra is placed through a 23Fr delivery sheath with the goal of final
deployment being along the mid to high RV septum.