Technical Considerations and Discussion:
We report three cases of Micra implantation following 52mm EVOQUE TTVR. Based on our experience, MICRA leadless pacemaker following EVOQUE TTVR is feasible via either a femoral or jugular venous approach, though the jugular approach tends to force the Micra to the apex, an undesirable position. The primary technical consideration during MICRA delivery was atraumatic placement of the delivery sheath across the valve prosthesis. Multiple fluoroscopic views were used. The MICRA delivery catheter was directed toward the ventricle in a right anterior oblique view (RAO), prior to advancing the system across the valve. A steep left anterior oblique (LAO) view (typically greater or equal to 45 degrees) providing an appropriate oblique angle for alignment of the delivery catheter with the lumen of the EVOQUE TTVR centrally was then obtained (See figure 1 b). We then utilized an RAO view to advance the MICRA delivery system to the interventricular septum in a position where it would not interact with the ventricular anchors of the EVOQUE TTVR (See figure 1c and supplemental videos). During the first two cases there was significant interaction between the tether and the valve prosthesis (See figure 1d). Due to this experience, in the third case the delivery cone was not retracted beyond the valve prosthesis, which resolved the issue. Early experience placing leadless pacemakers across recently implanted surgical bioprosthetic tricuspid valves suggested similar fluoroscopic approaches[17]. MICRA implant for each of the patients in our case series was completed while the patient was on full dose anti-coagulation without any significant bleeding complications recognized. The procedural time from vessel puncture to closure was short (14 minutes) for the two cases that were accomplished from the femoral vein. The case that involved switching to a jugular approach obviously took longer (54 minutes). Electrical data for each of the devices implanted was excellent, with a predicted device longevity of at least 7 years with a 100% pacing burden. In one case Micra AV was utilized and, at least early after implant, AV synchrony was achieved.
The use of percutaneous tricuspid valve interventions is predicted to grow significantly in the coming years as there continues to be no class I indication for surgical treatment of isolated TR[1-3]. Conduction system abnormalities post-TTVR will continue to be an important consideration for patients[6]. Given the lack of short-term or long-term data regarding pacemaker leads across TTVR implants, leadless pacemakers may offer an ideal solution for pacing support in this population by preventing interaction with the valve leaflets and structure. Additionally, given the usual age, frailty, and co-morbidities of patients undergoing TTVR, reducing infection risk is a primary concern and may be further reduced with leadless pacing[15].