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.