Micra Transcatheter Pacing System Research Articles

Transcatheter non-acute retrieval of the tine-based leadless ventricular pacemaker.

We report our single-centre experience of mid-term to long-term retrieval and reimplantation of a tine-based leadless pacemaker [Micra transcatheter pacing system (TPS)]. The TPS is a clinically effective alternative to transvenous single-chamber ventricular pacemakers. Whereas it is currently recommended to abandon the TPS at the end of device life, catheter-based retrieval may be favourable in specific scenarios. We report on nine consecutive patients with the implanted TPS who subsequently underwent transcatheter retrieval attempts. The retrieval system consists of the original TPS delivery catheter and an off-the-shelf single-loop 7 mm snare. The procedure was guided by fluoroscopy and intracardiac echocardiography. After an implantation duration of 3.1 ± 2.8 years (range 0.4-9.0), the overall retrieval success rate was 88.9% (8 of 9 patients). The mean procedure time was 89 ± 16 min, and the fluoroscopy time was 18.0 ± 6.6 min. No procedure-related adverse device events occurred. In the one unsuccessful retrieval, intracardiac echocardiography revealed that the TPS was partially embedded in the ventricular tissue surrounding the leadless pacemaker body in the right ventricle. After retrieval, three patients were reimplanted with a new TPS device. All implantations were successful without complications. A series of transvenous late retrievals of implanted TPS devices demonstrated safety and feasibility, followed by elective replacement with a new leadless pacing device or conventional transvenous pacing system. This provides a viable end-of-life management alternative to simple abandonment of this leadless pacemaker.

TIMES, ARE THEY A–CHANGING? IMPLANTATION AND FOLLOW–UP EXPERIENCE WITH LEADLESS PACEMAKERS (MICRA) AT PISA UNIVERSITY HOSPITAL

Abstract Background Leadless pacing represents a pivotal advancement in cardiac stimulation. Eliminating traditional pacing leads, leadless devices offer reduced complications, a bailout strategy for many previously challenging cases and streamlined procedures. Purpose This retrospective study aimed to compare, starting from December 1st 2023, newer implants (within the 3 years preceding Dec 1st 2023) and older implants (>3 years before) in a single–center experience with M–TPS (Micra Transcatheter Pacing System) in terms of safety and efficacy, at baseline and in a short–term follow–up (6 months). Methods A comprehensive analysis was conducted on 195 patients who underwent leadless pacemaker implantation at our Center, and that were followed–up for a minimum of 6 months. The cohort was stratified into two groups: recent (n=73) and less recent implants (n=122). Procedural variables, patient demographics, and clinical outcomes were documented. Post–implantation follow–up data include pacing threshold, fluoroscopy time, and other relevant variables. Results Comparison between the two groups revealed significant differences fluoroscopy time. Newer implants demonstrated a reduced fluoroscopy time [8 (IQR 5–12) vs 10 minutes (IQR 7–14)], suggesting potential advancements in technique. No significant differences were observed in other procedural or electrical parameters. Discussion: The comparison between older and newer leadless pacemaker implants reveals reassuring constancy in most parameters, suggesting the reliability of the M–TPS. The reduced fluoroscopy time aligns with the evolving proficiency of implanters and improved procedural efficiency. The dependable consistency observed across various parameters strengthens the confidence in the M–TPS, reinforcing its status as a reliable and effective solution for pacing. Conclusion The implantation and follow–up experience at our center elucidates very few differences between newer and older implants. This nuanced analysis contributes to the ongoing evolution of leadless pacemaker technology, which heralds a transformative era in cardiac care. With several years of implementation, accumulated follow–up data unveils valuable insights into its sustained effectiveness, guiding clinicians in optimizing patient outcomes and solidifying leadless pacing as a breakthrough in the realm of cardiac rhythm management.

MICRA AV implantation after transcatheter aortic valve replacement

BackgroundTranscatheter aortic valve replacement (TAVR) has evolved as a breakthrough therapy for patients with severe aortic valve stenosis. While TAVR has revolutionized the management of aortic valve disease, the procedure may be associated with the development of conduction disturbances requiring permanent pacemaker implantation. Traditionally, conventional transvenous pacemakers have been used to address these complications. However, the introduction of leadless pacemaker technology, such as the MICRA Transcatheter Pacing System (TPS), offers a novel alternative. Materials and methodsThis was a retrospective single-center study where all patients who underwent TAVR at our center and subsequently required permanent pacemaker implantation within 30 days were reviewed. We included only the patients who underwent leadless pacemaker placement. We then conducted a retrospective chart review to identify patient and procedural characteristics, procedural details, and relevant clinical outcomes. ResultsA total of 9 patients were identified. All of the patients underwent MICRA AV placement within 30 days post-TAVR by an interventional cardiologist. The average age of the cohort was 79.6 years with an average STS score of 3.7 %. The majority of the patients received balloon-expandable valves (78 %). There were no procedural complications in any of the patients. At an average follow-up of 353 days, capture thresholds and lead impedance remained stable with an average RV pacing of 13 %. ConclusionThis small, retrospective cohort demonstrates that the use of MICRA AV leadless pacemakers is feasible after TAVR and is associated with low periprocedural complications. Leadless pacemakers provide stable pacing thresholds and AV synchrony.

Acute pacing threshold elevation during simultaneous Micra leadless pacemaker implantation and AV node ablation: Clinical cases, computer model and practical recommendations.

In patients with refractory atrial fibrillation (AF), atrioventricular nodal (AVN) ablation and permanent pacemaker implantation is recommended. The Micra Transcatheter Pacing System (Micra) is a single chamber leadless pacemaker (LPM) and thus offers the possibility of AV node (AVN) ablation in the same procedure. Pacing threshold (PT) elevation after radiofrequency (RF) ablation is a potential complication. We conducted a single center retrospective cohort study. Patients implanted with a Micra (n = 84) and concomitant or delayed AVN ablation (n = 12) from 2014 to 2022 were included. Two cases of acute Micra PT elevation immediately following RF AVN ablation required device retrieval and implantation of a new Micra. Procedural characteristics and electrophysiological parameters were analyzed, and a computer model was performed to determine factors responsible for acute PT elevations. A total of 84 patients were included. Mean age was 74±10 and 48% were women. Twelve patients (14%) underwent AVN ablation. Two patients had acute PT elevation requiring device retrieval despite no direct contact of the ablation catheter with the Micra. Computer modeling shows that significant dissipated power due to electrical field coupling can occur at the tip or ring electrode if the catheter is not kept at a safe distance (≥35mm) from the Micra when a maximum power of 100W is delivered. Concurrent AVN ablation and Micra implantation is safe in most patients. To prevent acute PT elevation, keeping a safe distance of ≥35mm from the tip and ring electrodes of the Micra and using lower power output may prevent this complication.

Leadless pacing in the elderly: exit strategy or valid alternative?

Abstract Funding Acknowledgements Type of funding sources: None. Background The need for cardiac pacing progressively increases with age and the elderly constitute a special subset of patients, being often very fragile and at a greater risk for procedural complications. Leadless pacing systems appear to be a safe and effective option, being devoid of most complications associated with traditional transvenous pacing systems. Purpose This study aimed to analyze a single-center experience with M-TPS (Micra Transcatheter Pacing System) implantation in terms of safety and efficacy in a long-term follow-up. Methods Between May 2014 and November 2022, 193 patients underwent M-TPS implantation in our Center, all patients fulfilled standard criteria for pacemaker implantation with indication to receive either VVI or VDD pacing. We divided the study population into two groups according to age (group 1 < 79 y vs group 2 >= 80 y) and analyzed procedural outcomes, electrical performance of the system at follow-up (FU), rate of procedural major complications and of device-related events at FU. Results In 95/193 cases (69 males, 73%) M-TPS was implanted in patients > 80 y. There were no statistically significant differences between groups in baseline characteristics. Implant procedure was successful in all cases and no device-related events were registered during FU. Patients were followed-up for an average of 18 months, up to 7 years. No differences were observed between groups in procedure duration, single device delivery (group 1 vs group 2: 62.1 vs 69.6%, p=0.17), fluoroscopy time [10 (IQR 6-14) vs 8.5 (IQR 6-12.5) minutes, p=0.27], electrical performance at implant: pacing threshold [0.44 (0.38-0.63) vs 0.5 (0.38-0.75) V/0.24 ms, p=0.39]; impedance [710 (610-840) vs 700 (600-810) Ohm, p=0.56]; R wave amplitude [9.3 (6 -13.5) vs 8.2 (6 -11.9) mV, p=0.68] and at 6 months follow-up : pacing threshold [0.5 (0.38-0.5) vs 0.38 (0.38-0.5) V/0.24 ms, p=0.25]; impedance [580 (500-640) vs 570 (530-680) Ohm, p=0.38]; R wave amplitude [13.2 (9.5-17) vs 9.7 (7.8-16.7) mV, p=0.17]. The only statistically significant difference was found in the percentage of ventricular pacing (Vp%), which was higher in group 2 [5.3 (IQR 0.5-35) vs 38% (IQR 14-83), p=0.001] and stayed higher at a 12 months follow-up [11 (1-53) vs 60% (10-94)], p=0.001). High pacing threshold (>= 1mV@0.24ms) at implant was present in thirty-one patients (14 vs 19%, p=0.43). Conclusions As the population ages the incidence of rhythm disturbances raises, increasing the need for cardiac pacing. It is imperative to find a therapeutic solution that suits the elderly offering them high efficacy and a low rate of complications. MTP-S implant is an effective and safe procedure in elderly patients with similar electrical performance and outcomes compared with younger patients at long-term follow-up. While initially thought for patients that could not undergo traditional pacing interventions, MTP-S is now emerging as a valid substitute.

Feasibility and outcomes of Micra implant after cardiac implantable electronic device extraction

Abstract Funding Acknowledgements Type of funding sources: None. Background The specific and well-known design features of leadless pacing system (Micra Transcatheter Pacing System, M-TPS) have suggested his use in patients that previously underwent transvenous lead extraction (TLE) for any reason. The study aimed to investigate feasibility and long-term outcomes of M-TPS implant in patients underwent TLE. Methods Patients undergone M-TPS implantation in our Institution from May 2014 to September 2022 were included in the study. All patients fulfilled standard criteria for PM implantation (VVI or VDD mode). Follow-up (FU) was scheduled at discharge, after 1 month and every 6 months thereafter and electrical parameters were checked. Major complications were defined as life-threatening events, requiring surgical intervention or any event causing significant hemodynamic instability or resulting in death. Study population was divided between "naïve pacing" and "post-extraction" patients. Results We enrolled 193 patients (76.7% males), 57 (29.5%) received M-TPS implantation after TLE, needed because of infection in 91.4% of cases. Indications for pacing were permanent AF with bradycardia in 107 (55.5%) patients, complete AVB in 59 (30.5%), symptomatic sinus node dysfunction in 20 (10%), and advanced AVB or bifascicular bock in 7 (4%). There were no statistically significant differences between groups for demographics characteristics and primary PM implant indications, except mean age at implant that was significantly inferior in the post-extraction group [80 (IQR 75-84) vs 78 (IQR 72-83), p=0.04]. Implant procedure was successful in all and no complications were recorded. No differences between groups in procedure duration [40 (IQR 30-50) vs 45 (30-65) min, p=0.34], fluoroscopy time [9 (6-14) vs 9 (6-11) min, p=0.31] and single device delivery (64.9% vs 67.9%, p=0.35) were observed. The mean FU was 12 (1-36) months, maximum 8 years. Pacing variables at implantation [pacing threshold 0.5 (0.38-0.63) vs 0.5 (0.38-0.88) V/0.24 ms, p=0.15; impedance 720 (600-837) vs 675 (615-825) Ohm, p=0.51; R wave amplitude 9 (6.25-12.87) vs 8.2 (5.65-12) mV, p=0.47], discharge [pacing threshold 0.38 (0.38-0.63) vs 0.38 (0.38-0.63) V/0.24 ms, p=0.27; impedance 685 (580-770) vs 610 (560-750) Ohm, p=0.16; R wave amplitude 10.25 (7.2-14.5) vs 9.3 (6.5-16.5) mV, p=0.6], and at 6 months [pacing threshold 0.5 (0.38-0.5) vs 0.5 (0.38-1.25) V/0.24 ms, p=0.64; impedance 580 (520-680) vs 570 (510-640) Ohm, p=0.63; R wave amplitude 11.9 (8.2-16.4) vs 11.7 (9-20) mV, p=0.68; battery voltage 3.09 (3.05-3.11) vs 3.09 (3.04-3.13) V, p=0.71] did not show differences. Conclusion M-TPS is an efficacious and safe alternative to conventional PM, with the main advantage of the absence of transvenous leads and a surgically created subcutaneous pocket, avoiding all the related complications. These devices are a reliable alternative after TLE, with similar electrical performances than those observed in patients who did not previously received pacing.

Transcatheter pacing system implant: is it a matter of gender?

Abstract Funding Acknowledgements Type of funding sources: None. Background the leadless pacing system, like Micra Transcatheter Pacing System (M-TPS) is precisely designed to reduce peri- and post-procedural complications, like pneumothorax, lead dislodgement, infections, and lead fracture.Previous studies have already demonstrated its good safety profile and the excellent electrical performance during the follow up. The study aimed to investigate feasibility and long-term electrical outcomes of M-TPS implant and estimate sex differences in leadless pacing. Methods All patients undergone M-TPS implantation in our Institution from May 2014 to October 2022 were included. All patients fulfilled standard criteria for VVI or VDD pacing according to guidelines. Device FU was scheduled at discharge, after 1 month and then every 6 months. Electrical performance was checked. Major complications were defined as life-threatening events, requiring surgical intervention or significant hemodynamic instability or resulting in death. Study population was divided between genders in order to analyze potential differences during the FU Results One hundred ninety-three consecutive patients [148 males, 76.7%, mean age 79 (IQR 73-84) y] were enrolled in this study. Indications for pacing were permanent AF with bradycardia in 107 (55.5%) patients, complete AV block in 59 (30.5%) patients, symptomatic sinus node dysfunction in 20 (10%) patients, and advanced AV block or bifascicular bock in 7 (4%). One hundred seventy-seven patients received VVI pacing, while 16 VDD. There were no statistically significant differences between groups for demographics characteristics (mean age at implant 79 vs 81, p=0.12), except gender. The mean was FU 12 (IQR 1-36) months, maximum 8 years. The implant procedure was successful in all patients and no complications were recorded. We observed no differences between groups in procedure duration [40 (IQR 30-60) min vs 40 (IQR 29-50), p=0.64], fluoroscopy time [9 (6-14) min vs 9 (7-11), p=0.81] and single device delivery (65.7% vs 65.9%, p=0.34). Electrical performance, except for pacing threshold at implantation [0.5 (IQR 0.38-0.75) V/0.24ms vs 0.38 (IQR 0.25-0.63) V/0.24ms, p=0.02), was similar between groups at discharge [pacing threshold 0.38 (IQR 0.38-0.63) V/0.24 ms vs 0.38 (IQR 0.25-0.55) V/0.24 ms, p=0.30; impedance 650 (IQR 560-760) Ohm vs 675 (IQR 580-780) Ohm, p=0.71; R wave amplitude 10.1 (IQR 7-16.2)mV vs 9.5 (IQR 7-14.45) mV, p=0.71] and during the FU [pacing threshold 0.5 (IQR 0.38-0.63) V/0.24 ms vs 0.5 (IQR 0.38-0.5) V/0.24 ms, p=0.11; impedance 570 (IQR 490-630) Ohm vs 580 (IQR 510-640) Ohm, p=0.46; R wave amplitude 11.5 (IQR 7.8-15.7)mV vs 12.7 (IQR 9-18) mV, p=0.26]. Conclusion Leadless pacing therapy is a feasible and safe alternative to conventional pacemakers with similar electrical performance and outcomes during a long-term FU. No differences were found between genders making it a good option especially in women who are often considered fragile in surgical procedure.

P447 TRANSCATHETER PACING SYSTEM IMPLANT: IS IT A MATTER OF GENDER?

Abstract Background The use of a leadless pacing system, like Micra Transcatheter Pacing System (M–TPS), is nowadays a convincing alternative to transvenous pacemaker. PURPOSE: The study aimed to investigate feasibility and long–term electrical outcomes of M–TPS implant in a real–world population and to estimate sex differences in leadless pacing. Methods All patients undergone M–TPS implantation in our Institution from May 2014 to October 2022. Device follow–up was scheduled at discharge, after 1 month from procedure and then every 6 months. Electrical performance was checked. Major complications were defined as life– threatening events, requiring surgical intervention or any event causing significant hemodynamic instability or resulting in death. Study population was divided between genders to analyze potential differences and those observed during the follow–up (FU). Results One hundred ninety–three consecutive patients [148 males, 76.7%, mean age 79 (IQR 73–84) years] were enrolled in the study. There were no statistically significant differences between groups for demographics characteristics (mean age at implant 79 vs 81, p=0.12), except gender. The mean FU was 12 (IQR 1–36) months, maximum 8 years. The implant procedure was effectuve in all patients and no complications were recorded. We observed no differences between groups in procedure duration [40 (IQR 30–60) min vs 40 (IQR 29–50), p=0.64], fluoroscopy time [9 (6–14) min vs 9 (7–11), p=0.81] and single device delivery (65.7% vs 65.9%, p=0.34). Electrical performance, except for pacing threshold at implantation [0.5 (IQR 0.38–0.75) V/0.24ms vs 0.38 (IQR 0.25–0.63) V/0.24ms, p=0.02), was similar between groups at discharge [pacing threshold 0.38 (IQR 0.38–0.63) V/0.24 ms vs 0.38 (IQR 0.25–0.55) V/0.24 ms, p=0.30; impedance 650 (IQR 560–760) Ohm vs 675 (IQR 580–780) Ohm, p=0.71; R wave amplitude 10.1 (IQR 7–16.2)mV vs 9.5 (IQR 7–14.45) mV, p=0.71] and during the FU [pacing threshold 0.5 (IQR 0.38–0.63) V/0.24 ms vs 0.5 (IQR 0.38–0.5) V/0.24 ms, p=0.11; impedance 570 (IQR 490–630) Ohm vs 580 (IQR 510–640) Ohm, p=0.46; R wave amplitude 11.5 (IQR 7.8–15.7)mV vs 12.7 (IQR 9–18) mV, p=0.26]. Conclusion Leadless pacing therapy is a feasible and safe alternative to conventional pacemakers with comparable electrical performance and outcomes even during a long–term FU. No differences were found between genders making it a good option especially in women who are often considered fragile in surgical procedures.

Retrieval of an infectious leadless pacemaker with vegetation.

This case discusses the retrieval of a pacemaker with vegetation from a 78-year-old man. It suggests that grasping side of Micra body and pulling Micra into Agilis sheath is a possible technique for retrieval.

PO-678-07 IMPACT OF SINGLE VS MULTIPLE DEPLOYMENT ATTEMPTS ON CARDIAC PERFORATION DURING IMPLANTATION OF LEADLESS PACEMAKERS

Leadless pacemakers (LPs) are an excellent alternative for single ventricular pacing that avoid complications related to the pocket and leads. The Micra transcatheter pacing system is the only commercially available LP that is directly deployed into right ventricle. Due to the size of the delivery catheter, there is an inherent risk of right ventricle injury resulting in cardiac perforation that may require further management. Successful deployment requires sufficient trabeculations at the area of deployment and avoidance of the right ventricle free wall.

PO-663-02 A CASE SERIES OF SAFE EXTRACTION OF LEADLESS PACEMAKERS

The Micra transcatheter pacing system (Medtronic, Fridley, MN) has become a popular pacing system in patients with risk factors for, or a history of complications with transvenous pacemaker systems. With increasing utilization we have encountered cases needing device explant. In this case series we present a case series of 4 patients who underwent extraction of a leadless pacemaker system with implantation of a transvenous system.

Real-world experience on the safety and effectiveness of Micra TPS in patients with pre-existing in situ CIEDs

Abstract Background The Micra pre-market study showed that the Micra transcatheter pacing system could be safely implanted in patients with pacing indications. Patients with pre-existing cardiac implantable electronic devices (CIED) were excluded from this clinical trial; however, this group of patients might benefit from a leadless pacemaker especially when a lead fails or after incidence of system-related infections. Objective To determine the outcome of patients with a pre-existing CIED or lead that remains in situ at the time of Micra implant attempt. Methods Patients who had a pre-existing CIED and/or lead at the time of Micra implantation attempt were identified from the Micra Post-Approval Registry and Micra Acute Performance studies. Baseline characteristics were summarized, and a Fine-Gray competing risk model was used to compare risk for major complication through 24 months for patients with and without a pre-existing CIED. Results Of the 2323 patients included in the analysis, 111 patients had a pre-existing CIED or lead at the time of Micra implantation attempt that remained in situ. Types of pre-existing devices included 81 pacemakers (45 single chamber, 32 dual chamber, 4 of unknown type), 10 ICDs (2 single chamber, 2 dual chamber, 6 unknown type), 10 CRT devices (6 CRT-P, 4 CRT-D), 3 generators of unknown type, and 7 patients had only leads remaining. Patients with pre-existing devices were younger and less likely to have a pacing indication of bradyarrhythmia with atrial fibrillation compared to patients without pre-existing devices (p<0.001 for both). Patients with prior devices were more likely to have a condition precluding implant of a transvenous pacemaker (67.6% vs. 21.3%, p<0.001). The presence of a pre-existing CIED did not impact the outcome of the Micra TPS implant procedure: implant success was >99% for both cohorts. Mean follow-up duration was 21.2±14.3 months (range 0–56) for pre-existing devices patients and 23.3±15.8 months (range 0–62) for other patients. The rate of major complications through 24 months was 1.8% for patients with and 3.8% for patients without prior devices (p=0.36). There were no major complications related to device malfunction or device-device interaction. There were 6 system revisions in 4 patients with preexisting devices and 52 revisions in 51 patients without preexisting devices. Pacing thresholds for patients with and without prior devices were similar at implant (0.72 and 0.63, respectively; p=0.31) and remained stable through 12 months. Conclusion Micra can be safely and successfully implanted in patients with a pre-existing CIED remaining in situ. It should be considered a treatment option for patients in whom CIED extraction may be deemed high risk. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Medtronic, Inc. Risk of major complications

ACUTE PACING THRESHOLD ELEVATION DURING SIMULTANEOUS L0EADLESS PACEMAKER IMPLANTATION AND ATRIOVENTRICULAR NODE ABLATION

BACKGROUND In patients with refractory atrial fibrillation (AF) rate control strategy, atrioventricular node (AVN) ablation and permanent pacemaker implantation is recommended. The Micra Transcatheter Pacing System (TPS) is a single chamber leadless pacemaker implanted from the femoral vein and thus offers the possibility of AVN ablation in the same procedure. Here, we describe two cases of acute Micra TPS ventricular pacing threshold elevation immediately following radiofrequency AVN ablation at distance from the TPS requiring device retrieval and re-implantation of new Micra systems. METHODS AND RESULTS All consecutive patients with a Micra TPS implantation, at a single center, from November 2014 to March 2020, were analyzed retrospectively (n=56). Among them, 36% had a prior complication from a transvenous implant and in 16% lead extraction was performed concurrently with the TPS implantation. A total of ten patients (18%) underwent AVN ablation within the same procedure. Among them, two (20%) presented acute increase in the right ventricular pacing threshold after radiofrequency delivery requiring retrieval of the initial TPS and deployment of a new device. The first case was a 48 years-old man with previous heart transplantation. A Micra TPS was implanted in a mid-septal position (threshold 0,5 Volts x 0,24 milliseconds; impedance 800 Ohms; correct pull and hold test). To obtain a complete atrioventricular block, a retrograde arterial approach with an 8 mm nonirrigated catheter (60 degrees Celsius for 294 seconds) was required. After RF delivery, a loss of capture was observed. The second case included a 69 years-old woman. The TPS was implanted at an apico-septal position (Threshold 0,75 Volts x 0,24 milliseconds; impedance 720 Ohms; correct pull and hold test). The AVN ablation was achieved (52 degrees Celsius for 136 seconds) with a 4 mm nonirrigated catheter. Immediately, a threshold elevation >2 Volts x 0,24 milliseconds was observed. In both cases, continuous fluoroscopic control confirmed no direct interaction between the ablation catheter and the TPS. The device was successfully recaptured, and a new leadless PPM was immediately implanted with good results in these two cases. CONCLUSION We described two cases of acute threshold elevation during a combined procedure of TPS implantation and AVN ablation. This complication was not reported in series assessing safety of combining AVN ablation and Micra TPS implantation. We hypothesize a possible shunt of current to the distal electrode. An in vitro study is currently underway to explain the mechanism of indirect interaction between radiofrequency delivery and Micra TPS dysfunction. In patients with refractory atrial fibrillation (AF) rate control strategy, atrioventricular node (AVN) ablation and permanent pacemaker implantation is recommended. The Micra Transcatheter Pacing System (TPS) is a single chamber leadless pacemaker implanted from the femoral vein and thus offers the possibility of AVN ablation in the same procedure. Here, we describe two cases of acute Micra TPS ventricular pacing threshold elevation immediately following radiofrequency AVN ablation at distance from the TPS requiring device retrieval and re-implantation of new Micra systems. All consecutive patients with a Micra TPS implantation, at a single center, from November 2014 to March 2020, were analyzed retrospectively (n=56). Among them, 36% had a prior complication from a transvenous implant and in 16% lead extraction was performed concurrently with the TPS implantation. A total of ten patients (18%) underwent AVN ablation within the same procedure. Among them, two (20%) presented acute increase in the right ventricular pacing threshold after radiofrequency delivery requiring retrieval of the initial TPS and deployment of a new device. The first case was a 48 years-old man with previous heart transplantation. A Micra TPS was implanted in a mid-septal position (threshold 0,5 Volts x 0,24 milliseconds; impedance 800 Ohms; correct pull and hold test). To obtain a complete atrioventricular block, a retrograde arterial approach with an 8 mm nonirrigated catheter (60 degrees Celsius for 294 seconds) was required. After RF delivery, a loss of capture was observed. The second case included a 69 years-old woman. The TPS was implanted at an apico-septal position (Threshold 0,75 Volts x 0,24 milliseconds; impedance 720 Ohms; correct pull and hold test). The AVN ablation was achieved (52 degrees Celsius for 136 seconds) with a 4 mm nonirrigated catheter. Immediately, a threshold elevation >2 Volts x 0,24 milliseconds was observed. In both cases, continuous fluoroscopic control confirmed no direct interaction between the ablation catheter and the TPS. The device was successfully recaptured, and a new leadless PPM was immediately implanted with good results in these two cases. We described two cases of acute threshold elevation during a combined procedure of TPS implantation and AVN ablation. This complication was not reported in series assessing safety of combining AVN ablation and Micra TPS implantation. We hypothesize a possible shunt of current to the distal electrode. An in vitro study is currently underway to explain the mechanism of indirect interaction between radiofrequency delivery and Micra TPS dysfunction.

Pericardial effusion caused by accidently placing a Micra transcatheter pacing system into the coronary sinus

BackgroundLeadless pacemaker has been acknowledged as a promising pacing strategy to prevent pocket and lead-related complications. Although rare, cardiac perforation remains a major safety concern for implantation of Micra transcatheter pacing system (TPS).Case presentationA 83-year-old female with low body mass index (18.9 kg m−2) on dual anti-platelet therapy, was indicated for Micra TPS implantation due to sinus arrest and paroxysmal atrial flutter. The patient developed mild pericardial effusion during the procedure since the delivery catheter was accidentally placed into the coronary sinus for several times. Cardiac perforation with moderate pericardial effusion and pericardial tamponade was detected 2 h post-procedure. The patient was treated with immediately pericardiocentesis and recovered without further invasive therapy.ConclusionPericardial effusion caused by accidently placing a delivery catheter into the coronary sinus is rare but should be carefully considered in Micra TPS implantation, especially for those with periprocedural anti-platelet therapy.

Left femoral venous access for leadless pacemaker implantation: patient characteristics and outcomes

Abstract Funding Acknowledgements Type of funding sources: None. Background Leadless pacing has become an alternative approach for patients requiring a single-chamber pacemaker. Conventionally, Leadless Micra Transcatheter Pacing System (TPS) pacemakers are implanted via a right femoral venous access. However, due to various reasons, a left sided femoral venous approach may benecessary. We hypothesized that a left sided femoral venous approach is as safe and effective as compared to a right sided approach. Objective We assessed indications, procedural characteristics, safety and mid-term outcomes of Micra TPS implantation via a left femoral venous approach as compared to the conventional right sided approach. Methods and Results: In this retrospective single-center analysis, 143 consecutive patients undergoing Micra TPS implantation were included. 87% (125/143) underwent Micra TPS implantation via a right, and 13% (18/143) via a left femoral venous access. The mean age at implantation was 79.8 ± 7.5 years. Acute procedural success, mean procedure and fluoroscopy times as well as device parameters at implantation and follow-up (mean 15 ± 11.5 months) were similar between the two groups. Five major complications (3.5%) were encountered, all using a right-sided approach. After a transfemoral TAVI procedure, left femoral venous access was used in 42% of cases as compared to 8% in the remaining population (p = 0.003). Final leadless pacemaker position within the right ventricle was mid-septal in 82% (102/125) for right femoral access vs 72% (13/18) for left femoral access (p = 0.16). In the remaining cases (28 %, 5/18), the device was placed infero-septal following a left femoral venous access, as compared to 14% (18/125) for a right sided approach (p = 0.19). No repositioning was needed in 68% (85/125) using a right femoral access vs 72% (13/ 18) patients with a left femoral access (p = 0.84). Conclusions A left femoral venous access for Micra TPS implantation is safe and effective with an excellent implantation success rate similar to a conventional right femoral venous access without longer implantation and fluoroscopy times. The most frequent reason for choosing left- vs. right femoral venous access was a previous transfemoral TAVI procedure.

Late Retrieval of the Leadless Micra Transcatheter Pacemaker System

Aim: We report our single-center experience with the retrieval and replacement of the chronically implanted Micra transcatheter pacing system (TPS). Material and Methods: We included 6 patients with an implanted the Micra TPSs who subsequently underwent transvenous method of retrieval at our institution. The indication for device retrieval was pacemaker syndrome in two patients, battery depletion in three patients, and need for upgrade to biventricular pacing in one patient. Results: After an implantation duration of 555 ± 373 days, the overall retrieval success rate was 83.3%, 5 of 6 patients. No procedure-related adverse device events occurred. In the single patient with unsuccessful retrieval, intracardiac echocardiography revealed that the Micra TPS was embedded within the cardiac wall and surrounding tissue. After retrieval, four patients received a new Micra TPS. Conclusions: Late retrieval of an implanted Micra TPS was safe and feasible, which indicates the possibility for their safe and elective replacement with a new leadless pacing device.

Life cycle management of Micra transcatheter pacing system: Data from a high-volume center.

Data on the management of Micra transcatheter pacing system (TPS) at the time of an upgrade or during battery depletion is limited. We sought to evaluate the management patterns of patients implanted with a Micra TPS during long-term follow-up. We retrospectively identified patients who underwent Micra implantation from April 2014 to November 2019. We identified patients who underwent extraction (n = 11) or had an abandoned Micra (n = 12). We identified 302 patients who received a Micra during the period of the study. Mean age was 72.7 ± 15.4 years, 54.6% were men, and left ventricular ejection fraction was 51.9 ± 5.2%. Mean follow-up was 1105.5 ± 529.3 days. Procedural complications included pericardial tamponade (n = 1) treated with pericardiocentesis, significant rise in thresholds (n = 6) treated with reimplantation (n = 4), and major groin complications (n = 2). Indications for extraction included an upgrade to cardiac resynchronization therapy (CRT) device (n = 3), bridging after extraction of an infected transvenous system (n = 3), elevated thresholds (n = 3), and non-Micra-related bacteremia (n = 2). The median time from implantation to extraction was 78 days (interquartile range: 14-113 days), with the longest extraction occurring at 1442 days. All extractions were successful, with no procedural or long-term complications. Indications for abandonment included the need for CRT (n = 6), battery depletion (n = 2), increasing thresholds/failure to capture (n = 3), and pacemaker syndrome (n = 1). All procedures were successful, with no procedural or long-term complications. In this large single-center study, 6% of patients implanted with a Micra required a system modification during long-term follow-up, most commonly due to the requirement for CRT pacing. These patients were managed successfully with extraction or abandonment.

Leadless pacing in the elderly: never too old for something new.

Rates of cardiac pacemaker implantation rise with age, and, meanwhile, elderly patient may be at great risk of complications, as pneumothorax, lead perforation, or pocket dehiscence. The use of leadless pacemaker could overcome peri- and post-procedural complications related to the presence of transvenous leads and pocket. The study aims to investigate feasibility and outcomes of Micra Transcatheter Pacing System (M-TPS) implantation in elderly, which represents a challenge for conventional cardiac pacing. Between May 2014 and July 2019, 109 patients (88 males, mean age 77.71±9.68 years) underwent M-TPS implantation at our Center, targeting a non-apical site of delivery when feasible. Study population was divided into two groups according to age (group 1 <79 years vs group 2 group 2 ≥80 years). The outcome evaluation included electrical performance at hospital discharge, and during follow-up. In 46/109 cases (34 males, 73.91%) M-TPS was implanted in patients older than 80 years. There were no statistically significant differences between groups for demographics characteristics, except for age. The procedure was performed via the right femoral access in 102/109 cases and was successful in all cases, with no device-related events. No differences were observed between groups in procedure duration, single device delivery, electrical performance at implant and at 12 month F-U. MTP-S implant is an effective and safe procedure in elderly patients, with similar electrical performance and outcome compared with younger patients at mid-term follow-up.

Micra Transcatheter Pacing System Implant under Direct Visualization During Minimally Invasive Tricuspid Valve Surgery

Atrioventricular nodal conduction abnormalities are common after open heart surgery and more so during or after valve surgery. The incidence of atrioventricular (AV) block after tricuspid valve (TV) surgery is higher than what is observed following coronary artery bypass surgery or left sided valve interventions due to the proximity of the TV annulus to the AV node and hence requirements for cardiac pacing are high. However, the mechanical interference between pacing leads and TV leaflet mobility and coaptation can result in regurgitation rendering such an approach counterintuitive. We report a case of Micra Transcatheter pacing system (TPS) implant under direct visualization at the time of tricuspid valve surgery performed via a right mini-thoracotomy approach.

Abstract 16795: Fate of Dislodged Micra Transcatheter Pacing System in Coronary Sinus

Background: Micra Transcatheter Pacing System is a leadless pacemaker for treatment of symptomatic high-grade atrioventricular block and persistent atrial fibrillation. We present a case report of dislodgement of a Micra device into the coronary sinus. Case presentation: An 87 year old man with permanent atrial fibrillation presented to the hospital with dizziness and fall. His medications included Lasix and Metoprolol. Electrocardiogram revealed atrial fibrillation with slow ventricular response. Metoprolol was held. During the hospital stay, telemetry monitoring revealed heart rates of 30-40 bpm. Micra device implantation was indicated for symptomatic bradycardia. After deployment, the Micra dislodged into the right atrium. Efforts to retrieve the device led to its embolism into mid-coronary sinus and dissection of the coronary sinus. Given comorbidities, the Micra was deactivated and a single chamber pacemaker was implanted with serial radiographic monitoring of Micra. Post procedure Chest X-ray (Fig. 1) and Computed Tomography Angiography of the chest (Fig. 2) confirmed location of Micra in the coronary sinus. Discussion: This is the first described case of dislodged Micra device in the coronary sinus. Device retrieval attempts resulted in dissection of the coronary sinus and there was no myocardial capture when pacing from the device. Serial CXR showed stable Micra position over the next two years. Conclusion: Embolization and dislodgement of Micra leadless pacemaker into the coronary sinus is possible and chronic management with serial imaging after abandoning the device is feasible.