Safety and feasibility of AutoCapture™ Pacing System in patients undergoing LBBAP

Real World Experience of Leadless LV Endocardial CRT with the WiSE CRT Pacing System; An International Study

Utilization of cardiac magnetic resonance imaging (cMRI) as an imaging modality in clinical practice is rapidly increasing. More evidence from randomized studies establishing clinical safety and performance of pacing systems in patients undergoing a cMRI scan is needed. The purpose of this prospective, multicenter, randomized study was to demonstrate safety and efficacy of the Accent MRI™ conditional pacing systems (St. Jude Medical, St. Paul, MN, USA) in patients undergoing cMRI scan. Patients (n=283) indicated for dual-chamber pacemaker implant were randomized to either the MRI Group (MG) (n=140) or the Control Group (CG) (n=143) after successful device implantation of the Accent MRI™ system. Clinical evaluation and device interrogation were performed at pre- and post-MRI scan, and 1 month post-MRI for all patients. At 9-12weeks postimplant, patients in MG underwent a nondiagnostic cMRI scan at 1.5 Tesla (T), while patients in CG underwent device interrogation and clinical evaluation twice with a 45-minute waiting period in between. The safety endpoint was freedom from MRI scan-related complications and that for efficacy was significant changes in right atrial/ventricular capture threshold and sensing amplitude between right before MRI, immediately after MRI, and 1 month post-MRI. Results showed 100% freedom from MRI scan-related complications. There were no significant changes in device performance between pre-MRI scan and 1 month post-MRI scan time points in both study groups. cMRI scanning with 1.5 T scanners is safe in patients implanted with the Accent MRI™ conditional pacing system and has no significant effect on the electrical parameters of the device and leads.

Modern pacemakers are designed to allow patients to undergo magnetic resonance imaging (MRI) under a set of specific conditions. Aim of this study is to provide confirmatory evidence of safety and performance of a new pacing system (ImageReady™, Boston Scientific) in patients undergoing 1.5 and 3T MRI. Two prospective, nonrandomized, single-arm studies were designed to provide confirmatory data of no impact of MRI on device function, lead parameters, and patient conditions in subjects implanted with the system undergoing a clinically non-indicated 1.5T and 3T MRI, respectively. Device measurements were done within 1 hour before and after the scan and at 1 month follow-up. Thirty-two subjects underwent MRI visit (17 subjects with 1.5T MRI and 15 subjects with 3T MRI). There were no unanticipated adverse effects related to the pacemaker. Device measurements taken pre- and post-MRI scan did not show any clinical relevant change that could indicate an effect of the MRI on the device or at the lead-tissue interface (RV threshold change: 0.01±0.13 V, P = 0.60; RA threshold change: 0.01±0.11 V, P = 0.53; R wave change: -0.44±1.73 mV, P = 0.36; R wave change: 0.12±1.67 mV, P = 0.73), with data confirmed at 1-month follow-up visit. The study documented safety of the pacing system in the 1.5T and 3T MRI environment by showing no adverse events related to device or MRI scan. Additional data are required to cover the more complex scenarios involving different diagnostic needs, conditions of use, clinical conditions, and new emerging technologies.

ObjectivesTo evaluate at 1.5 and 3 T MRI the safety and performance of trademarked ENO®, TEO®, or OTO® pacing systems with automated MRI Mode and the image quality of non-enhanced MR examinations.MethodsA total of 267 implanted patients underwent MRI examination (brain, cardiac, shoulder, cervical spine) at 1.5 (n = 126) or 3 T (n = 141). MRI-related device complications, lead electrical performances stability at 1-month post-MRI, proper functioning of the automated MRI mode and image quality were evaluated.ResultsFreedom from MRI-related complications at 1 month post-MRI was 100% in both 1.5 and 3 T arms (both p < 0.0001). The stability of pacing capture threshold was respectively at 1.5 and 3 T (atrial:: 98.9% (p = 0.001) and 100% (p < 0.0001); ventricular: both 100% (p < 0001)). The stability of sensing was respectively at 1.5 and 3 T (atrial: 100% (p = 0.0001) and 96.9% (p = 0.01); ventricular: 100% (p < 0.0001) and 99.1% (p = 0.0001)). All devices switched automatically to the programmed asynchronous mode in the MRI environment and to initially programmed mode after the MRI exam. While all MR examinations were assessed as interpretable, artifacts deteriorated a subset of examinations including mostly cardiac and shoulder ones.ConclusionThis study demonstrates the safety and electrical stability of ENO®, TEO®, or OTO® pacing systems at 1 month post-MRI at 1.5 and 3 T. Even if artifacts were noticed in a subset of examinations, overall interpretability was preserved.Clinical relevance statementENO®, TEO®, and OTO® pacing systems switch to MR-mode when detecting magnetic field and switch back on conventional mode after MRI. Their safety and electrical stability at 1 month post MRI were shown at 1.5 and 3 T. Overall interpretability was preserved.Key Points• Patients implanted with an MRI conditional cardiac pacemaker can be safely scanned under 1.5 or 3 Tesla MRI with preserved interpretability.• Electrical parameters of the MRI conditional pacing system remain stable after a 1.5 or 3 Tesla MRI scan.• The automated MRI mode enabled the automatic switch to asynchronous mode in the MRI environment and to initial settings after the MRI scan in all patients.

BackgroundThe use of magnetic resonance imaging (MRI)-conditional permanent pacemakers has increased significantly. In this meta-analysis, we examine the safety of MRI-conditional pacing systems in comparison with conventional systems.MethodsAn electronic search was performed using major databases, including studies that compared the outcomes of interest between patients receiving MRI-conditional pacemakers (MRI group) versus conventional pacemakers (control group).ResultsSix studies (5 retrospective and 1 prospective non-randomised) involving 2,118 adult patients were identified. The MRI-conditional pacemakers, deployed in 969 patients, were all from a single manufacturer (Medtronic Pacing System with 5086 leads). The rate of pacemaker lead dislodgement (atrial and ventricular) was significantly higher in the MRI group (3% vs. 1%, OR 2.47 (95% CI 1.26; 4.83), p = 0.008). The MRI group had a significantly higher rate of pericardial complications (2% vs. 1%, OR 4.23 (95% CI 1.18; 15.10), p = 0.03) and a numerically higher overall complication rate in comparison with the conventional group (6% vs. 3%, OR 2.02 (95% CI 0.88; 4.66), p = 0.10) but this was not statistically significant.ConclusionsIn this meta-analysis, the rates of pacemaker lead dislodgement and pericardial complications were significantly higher with the Medtronic MRI-conditional pacing system.

Temporary cardiac pacing is used in the emergency treatment of life-threatening bradyarrhythmias and for the support of heart rate and blood pressure of patients with sick sinus syndrome or high-grade atrioventricular (AV) block undergoing general anesthesia, typically for permanent pacemaker implantation. We retrospectively evaluated the safety and efficacy of a noninvasive transthoracic external cardiac pacing system in 42 dogs treated for bradyarrhythmias. Optimal placement of the patch electrodes on the skin of the thorax was initially established on 2 anesthetized normal dogs. The optimal electrode placement was determined to be on the right and left hemithoraces, directly over the heart. Afterward, by means of this electrode placement all 42 dogs treated for bradyarrhythmias in this study were successfully paced with the noninvasive transthoracic system. Dogs ranged in age from 1 to 15 years and weighed between 3.2 and 40 kg. Miniature Schnauzers, German Shepherds, and mixed breeds were most common in the study population. Indications for noninvasive transthoracic pacing included emergency treatment of hemodynamically unstable 3rd-degree AV block (2 dogs): support of heart rate during general anesthesia for permanent pacemaker implantation or lead-wire adjustment (38 dogs): and support of heart rate during general anesthesia for ophthalmologic surgery in dogs with sick sinus syndrome (2 dogs). Complications included pain and skeletal muscle stimulation, which required general anesthesia. We conclude that the noninvasive transthoracic pacing system evaluated is satisfactory for clinical veterinary use.

Pacemaker-dependent (PD) patients undergoing implantable cardiac electronic device extraction often must be subjected to temporary pacing interventions. We sought to determine the safety and utility of a leadless pacing system (Micra™; Medtronic, Minneapolis, MN, USA) in patients undergoing system extraction as compared with externalized temporary transvenous right ventricular lead (temp-perm) placement. We performed a retrospective cohort analysis of all patients receiving either permanent Micra™ or temp-perm systems following system extraction from October 2013 to September 2017 at Vanderbilt University Hospital. The Micra™ and temp-perm cohorts included nine and 27 patients meeting the inclusion criteria, respectively. System infection was the most common indication for extraction (67% Micra™, 84% temp-perm), but no patients had active bacteremia at the time of permanent system reimplantation. There was no difference in system type (p = 0.09) or mean lead dwell time extracted (109 versus 81 months; p = 0.93). Procedure times were comparable between the two groups (180 versus 194 minutes; p = 0.74). Patients receiving Micra™ systems had shorter hospital stays after extraction (two versus eight days; p < 0.005), with no difference in major complications (11% versus 15%; p = 0.78) or 30-day (11% versus 7%; p = 0.77) or 90-day (11% versus 11%; p = 0.45) mortality. No reinfections were observed in either group at 90 days. Implantation of the Micra™ pacing system in select PD patients after system extraction is feasible and appears to reduce the hospital length of stay as compared with the use of temp-perm systems.

The use of exogenous iron by professional cyclists pervades abdominal organs but not the heart

The aim of this study was to evaluate the safety and performance of the Autocapture pacing system during a 5-year follow-up period. The study was conducted retrospectively between May 1996 and May 2001. Sixty consecutive patients who had undergone VVI pacemaker implantation using an Autocapture program with leads 1402T (n: 31) and 1452T (n: 29) were included in the study. Intraoperative measurements including a ventricular stimulation threshold test, sensing of intrinsic R wave (mV), and lead impedance (W) were done by a standard pacing system analyzer. Evoked responses (ER, mV) and polarization signals (PS, mV) were measured after the pocket was closed. Pacing thresholds by Autocapture (AC thrd, V) and Vario (Vario thrd, V), battery current (mA), and battery impedance (kW) were also repeated during predischarge and 1, 6, 12, 18, 24, 30, 40, 50, and 60 months after discharge. According to the ER and PS values an Autocapture algorithm could be activated in 49 patients (88%). The Autocapture algorithm remained active during the follow-up in all of these patients. In patients with inappropriate ER and PS values (11 patients, 12%), pacemakers were programmed to a VVIR pacing mode and Autocapture algorithm was inactivated. ER and PS values did not reach appropriate values to activate the Autocapture algorithm in any of these patients in consecutive follow-ups. Twenty-four-hour Holter monitoring could be conducted in 32 patients (53%). In all recordings, when the loss of capture occurred, it was confirmed that back-up pacing continued. When the first measurements recorded during implantation were compared to approximately the 5th year measurements; ER (9.2 mV vs 9.6 mV), PS signal (1.13 +/- 0.30 mV vs 1.15 +/- 0.72 mV), AC thrd (0.4 V vs 1.2 V), Vario thrd (0.7 V vs 1.3 V), and lead impedance (502 ohm vs 620 ohm) were not changed significantly. Battery impedance increased 1 kOhm between 30-40 months of the implantation. Seven deaths occurred during follow-up. Three patients had fatal myocardial infarction, one died due to a non-cardiac event, and the remaining three died due to progressive heart failure. ER, R wave amplitude, and PS, which are the main parameters for the continuation of Autocapture function, did not change significantly during long-term follow-up. High output back up pacing provided additional safety for sudden rises in threshold. The Autocapture pacing algorithm was found to be effective and reliable during long-term follow-up.

Purpose: There are limited published data from controlled studies on pacemaker implanted patients who underwent a Cardiac MRI scan. The purpose of this prospective, international, multi-center, randomized study was to demonstrate safety and efficacy of the SJM MRI conditional pacing system in patients undergoing cardiac MRI scan. Methods: Patients (n = 283) indicated for dual chamber pacemaker implant were invited to provide voluntary consent at 15 centers across Asia and randomized either to the MRI scan group (SG; n = 140) or the Control group (CG; n = 143) post successful device implantation (Accent MRITM DDDR, Tendril MRITM lead, St. Jude Medical). Each patient in SG (within 9 – 12 weeks post-implant) underwent an elective, prespecificed, non-diagnostic cardiac MRI scan in a 1.5 Tesla horizontal cylindrical bore scanning machine with total magnet exposure time of approximately 60 minutes, maximized gradient slew rate of up to 200 T/m/s and whole body SAR < 4W/kg. Clinical evaluation and device interrogation were performed at baseline, pre and post MRI scan visit and 1-month post MRI for all enrolled patients. The primary endpoint for device safety was freedom from MRI-related complications. The primary endpoint for device efficacy was change in RA/RV capture threshold and sensing amplitude from the MRI visit to 1 month post-MRI visit. Summary of results: The study achieved both safety and efficacy endpoints with 118 patients completing the 1 month post MRI scan visit reporting 100% freedom from MRI scan related complications at the 1 Month post Cardiac MRI Scan follow-up visit (95% LCB: 97.4%). The study reported 12 SADEs & 28 SAEs all of which were found to be not related to MRI scan. No significant changes in device performance with respect to RA/RV capture threshold and RA/RV sensing amplitude from the MRI visit to 1 month post-MRI visit were observed between CG and SG groups (Table 1). Change in RA/RV lead efficacy parameters# #Minimum 113 subjects were required in each group to achieve more than 90% of power at a one sided significant level of 5% to show the non-inferiority with a margin of 10% *n - Number of subjects who experienced an increase in RA capture threshold @ 0.5 ms at 1 M post-MRI scan ≤ 0.5V compared to pre-MRI testing *n - Number of subjects who experienced a decrease in RA sensing amplitude ≤ 50% and ≥ 1.5 mV at 1 M post-MRI scan compared to pre-MRI testing Change in RA/RV lead efficacy parameters# #Minimum 113 subjects were required in each group to achieve more than 90% of power at a one sided significant level of 5% to show the non-inferiority with a margin of 10% *n - Number of subjects who experienced an increase in RA capture threshold @ 0.5 ms at 1 M post-MRI scan ≤ 0.5V compared to pre-MRI testing *n - Number of subjects who experienced a decrease in RA sensing amplitude ≤ 50% and ≥ 1.5 mV at 1 M post-MRI scan compared to pre-MRI testing Conclusions: This study of the St. Jude Medical Accent MRITM pacemaker system in patients undergoing 1.5T cardiac MRI scans at up to 4W/kg successfully met the safety and efficacy endpoints.

Clinical safety of the ProMRI pacemaker system in patients subjected to head and lower lumbar 1.5-T magnetic resonance imaging scanning conditions

ObjectiveThis study aimed to investigate what factors affect reconstruction timing of pacing system, and to explore how to optimise reconstruction timing of pacing system. The study will provide a new...

Design and rationale of the MODULAR ATP global clinical trial: A novel intercommunicative leadless pacing system and the subcutaneous implantable cardioverter-defibrillator.

Objective: To explore the utility and safety of leadless intracardiac transcatheter pacing system. Methods: The study was a prospective observational study. Patients underwent Micra transcatheter pacing system in Beijing Anzhen hospital from December 2019 to January 2020 were enrolled. The baseline characteristics, platelet count, hemoglobin, anticoagulation and/or antiplatelet therapy, mean procedural time, average fluoroscopy time, number of deployment and electrical parameters (threshold, R-wave amplitude, impedance) were recorded. Ultrasonography of bilateral femoral and iliac veins was performed in all patients. Patients were followed including access site complication, adverse event and device evaluation at implant, hospital discharge, 1 and 3 months post-implant. R-wave≥5 mV, impedance between 400 and 1 500 Ω and threshold increase≤1.5 V than implant is considered a stable parameter. Femoral access site complications included hematoma, hemorrhage, pseudoaneurysm, and arteriovenous fistula. Adverse events included dislodgement, cardiac effusion/perforation and infection. Left ventricular end diastolic diameter and ejection fraction before and at 1 month after implant were reported. Results: Five patients were enrolled and pacemaker implantation was successful in all 5 patients. Patients were all males and the average age was (78.4±8.4) years. 2 patients received aspirin and clopidogrel therapy, 1 patient suffered from anemia and thrombocytopenia occurred in 1 patient. No stenosis, occlusion and vascular malformation of bilateral femoral and iliac veins was observed. The mean implant time was (39.6±1.7) minutes. The average fluoroscopy time was (9.2±1.3) minutes and the number of deployment was (1.40±0.55). Electrical parameters(threshold, R-Wave amplitude and impedance) were as follows: (0.40±0.10) V/0.24 ms, (10.80±3.72) mV and (822.00±162.23) Ω at implant; (0.45±0.07) V/0.24 ms, (13.04±2.41) mV, and (748.0±91.5) Ω at discharge, (0.40±0.06) V/0.24 ms, (14.26±4.11) mV, and (700.0±91.7) Ω at 1 month post-implant and (0.39±0.05) V/0.24 ms, 14.40±3.97 mV, and (682.0±96.0) Ω at 3 months post-implant, respectively. Threshold increase was ≤1.5 V compared to that during implantation, electrical parameters were acceptable and stable. There was no difference in LVEDD [(44.00±5.24) mm vs. (44.00±5.34) mm,P=1.000] and EF [(62.00±3.39)% vs. (62.20±3.56)%, P=0.861] before and 1 month post-implant. No incidence of access site complications, cardiac effusion/perforation, dislodgment or infections occurred during the 3 months. Conclusions: The leadless transcatheter pacemaker implantation performed in our study archived a high implant success rate and favorable safety profile as well as associated with low and stable pacing thresholds. The long-term safety and benefit of leadless pacemaker need to be evaluated in future clinical studies.

This editorial refers to ‘Feasibility, safety and short-term outcome of leadless ultrasound-based endocardial left ventricular resynchronization in heart failure patients. Results of the Wireless Stimulation Endocardially for CRT (WiSE-CRT) study’ by A. Auricchio et al ., on page 681 . Cardiac resynchronization therapy (CRT) entails placement of a left ventricular (LV) lead in patients with heart failure, systolic dysfunction, and dyssynchrony in order to coordinate electrical and mechanical ventricular activation to improve ventricular function. Cardiac resynchronization therapy improves functional capacity, reduces heart failure hospitalization, and prolongs survival in recipients1,2 However, 30–35% of patients fail to respond to CRT.3 Mechanisms proposed to account for non-response have included poor patient selection, suboptimal LV lead position with regard to LV segment, and more recently, epicardial as opposed to endocardial electrical activation of the LV.4 To overcome these limitations, a leadless endocardial LV pacing system (WiCs-LV system) has been developed. In the WiCs system, a small, bullet-like, wireless LV endocardial bipolar electrode is deployed that transduces ultrasound energy into electrical pacing pulses. A subcutaneous pulse generator is implanted alongside a standard pacemaker or defibrillator (the ‘co-implant’). The subcutaneous pulse generator detects the co-implant's right ventricular (RV) pacing pulse, triggering generation of an ultrasound pulse that the LV endocardial plug converts to a near-synchronous LV pacing waveform. In this issue of the Journal , Auricchio et al. 5 report on the feasibility and safety of the wireless endocardial LV pacing system. Left ventricular pacing via a lead in the epicardial coronary venous system introduces many potential mechanisms of non-response. Coronary venous valves, tortuosity, or absence of branches (particularly in the setting of ischaemic disease or previous surgery) may preclude pacing the site of latest activation. Epicardial LV leads have higher pacing thresholds than endocardial leads, dislodge in 6% of patients, and result …