Fleur V.Y. Tjong

Permanent Leadless Cardiac Pacing: Results of the LEADLESS Trial

Background— Conventional cardiac pacemakers are associated with several potential short- and long-term complications related to either the transvenous lead or subcutaneous pulse generator. We tested the safety and clinical performance of a novel, completely self-contained leadless cardiac pacemaker. Methods and Results— The primary safety end point was freedom from complications at 90 days. Secondary performance end points included implant success rate, implant time, and measures of device performance (pacing/sensing thresholds and rate-responsive performance). The mean age of the patient cohort (n=33) was 77±8 years, and 67% of the patients were male (n=22/33). The most common indication for cardiac pacing was permanent atrial fibrillation with atrioventricular block (n=22, 67%). The implant success rate was 97% (n=32). Five patients (15%) required the use of >1 leadless cardiac pacemaker during the procedure. One patient developed right ventricular perforation and cardiac tamponade during the implant procedure, and eventually died as the result of a stroke. The overall complication-free rate was 94% (31/33). After 3 months of follow-up, the measures of pacing performance (sensing, impedance, and pacing threshold) either improved or were stable within the accepted range. Conclusions— In a prospective nonrandomized study, a completely self-contained, single-chamber leadless cardiac pacemaker has shown to be safe and feasible. The absence of a transvenous lead and subcutaneous pulse generator could represent a paradigm shift in cardiac pacing. Clinical Trial Registration— URL: . Unique identifier: [NCT01700244][1]. # CLINICAL PERSPECTIVE {#article-title-26} [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT01700244&atom=%2Fcirculationaha%2F129%2F14%2F1466.atomBackground— Conventional cardiac pacemakers are associated with several potential short- and long-term complications related to either the transvenous lead or subcutaneous pulse generator. We tested the safety and clinical performance of a novel, completely self-contained leadless cardiac pacemaker. Methods and Results— The primary safety end point was freedom from complications at 90 days. Secondary performance end points included implant success rate, implant time, and measures of device performance (pacing/sensing thresholds and rate-responsive performance). The mean age of the patient cohort (n=33) was 77±8 years, and 67% of the patients were male (n=22/33). The most common indication for cardiac pacing was permanent atrial fibrillation with atrioventricular block (n=22, 67%). The implant success rate was 97% (n=32). Five patients (15%) required the use of >1 leadless cardiac pacemaker during the procedure. One patient developed right ventricular perforation and cardiac tamponade during the implant procedure, and eventually died as the result of a stroke. The overall complication-free rate was 94% (31/33). After 3 months of follow-up, the measures of pacing performance (sensing, impedance, and pacing threshold) either improved or were stable within the accepted range. Conclusions— In a prospective nonrandomized study, a completely self-contained, single-chamber leadless cardiac pacemaker has shown to be safe and feasible. The absence of a transvenous lead and subcutaneous pulse generator could represent a paradigm shift in cardiac pacing. Clinical Trial Registration— URL: http://clinicaltrials.gov. Unique identifier: NCT01700244.

State of the art of leadless pacing

Despite undisputable benefits, conventional pacemaker therapy is associated with specific complications related to the subcutaneous device and the transvenous leads. Recently, two miniaturized leadless pacemakers, Nanostim™ (St. Jude Medical) and Micra™ (Medtronic), which can be completely implanted inside the right ventricle using steerable delivery systems, entered clinical application. The WiCS™-cardiac resynchronisation therapy (CRT) system (wireless cardiac stimulation for CRT, EBR Systems) delivers leadless left ventricular endocardial stimulation for cardiac resynchronization. In addition to obvious cosmetic benefits, leadless pacing systems may have the potential to overcome some complications of conventional pacing. However, acute and long-term complications still remains to be determined, as well as the feasibility of device explantation years after device placement.

Communicating Antitachycardia Pacing-Enabled Leadless Pacemaker and Subcutaneous Implantable Defibrillator

Transvenous lead-related complications occur throughout the spectrum of cardiac rhythm management device therapies [(1)][1]. These complications incur significant cost to the health care system and have tremendous impact on patient quality of life. The subcutaneous implantable-cardioverter

Permanent Leadless Cardiac Pacemaker Therapy: A Comprehensive Review.

A new technology, leadless pacemaker therapy, was recently introduced clinically to address lead- and pocket-related complications in conventional transvenous pacemaker therapy. These leadless devices are self-contained right ventricular single-chamber pacemakers implanted by using a femoral percutaneous approach. In this review of available clinical data on leadless pacemakers, early results with leadless devices are compared with historical results with conventional single-chamber pacing. Both presently manufactured leadless pacemakers show similar complications, which are mostly related to the implant procedure: cardiac perforation, device dislocation, and femoral vascular access site complications. In comparison with conventional transvenous single-chamber pacemakers, slightly higher short-term complication rates have been observed: 4.8% for leadless pacemakers versus 4.1% for conventional pacemakers. The complication rate of the leadless pacemakers is influenced by the implanter learning curve for this new procedure. No long-term outcome data are yet available for the leadless pacemakers. Larger leadless pacing trials, with long-term follow-up and direct randomized comparison with conventional pacing systems, will be required to define the proper clinical role of these leadless systems. Although current leadless pacemakers are limited to right ventricular pacing, future advanced, communicating, multicomponent systems are expected to expand the potential benefits of leadless therapy to a larger patient population.

Postmortem Histopathological Examination of a Leadless Pacemaker Shows Partial Encapsulation After 19 Months.

An 80-year-old male, with a history of coronary artery disease (coronary artery bypass graft surgery) and bradytachy syndrome was referred for a recurring pacemaker pocket infection of his dual chamber pacemaker system. The infected system was explanted and the leads extracted using laser, followed by antibiotic treatment. As the patient only required infrequent pacing, the choice for a single chamber pacing system was made. In January 2013, a leadless pacemaker (LP; Nanostim, St. Jude Medical, MN) was successfully implanted in the right ventricular (RV) apex. Four months postimplant, a transesophageal echocardiographic examination reconfirmed correct deployment of the LP in the RV apex, and the distal end of the LP moving freely during myocardial contraction (Figure 1A and 1B; Data Supplement), touching the lateral RV wall but not interfering with the RV septum (Movie in the Data Supplement). The LP did not interfere with the RV outflow tract, pulmonary valve or tricuspid valve, and no mobile structures were identified on the LP. The patient was monitored in the pacemaker outpatient clinic …

Clinical and serum-based markers are associated with death within 1 year of de novo implant in primary prevention ICD recipients

BACKGROUND Implantable cardioverter-defibrillator (ICD) implantation is contraindicated in those with <1-year life expectancy. OBJECTIVES The aim of this study was to develop a risk prediction score for 1-year mortality in patients with primary prevention ICDs and to determine the incremental improvement in discrimination when serum-based biomarkers are added to traditional clinical variables. METHODS We analyzed data from the Prospective Observational Study of Implantable Cardioverter-Defibrillators, a large prospective observational study of patients undergoing primary prevention ICD implantation who were extensively phenotyped for clinical and serum-based biomarkers. We identified variables predicting 1-year mortality and synthesized them into a comprehensive risk scoring construct using backward selection. RESULTS Of 1189 patients deemed by their treating physicians as having a reasonable 1-year life expectancy, 62 (5.2%) patients died within 1 year of ICD implantation. The risk score, composed of 6 clinical factors (age ≥75 years, New York Heart Association class III/IV, atrial fibrillation, estimated glomerular filtration rate <30 mL/min/1.73 m(2), diabetes, and use of diuretics), had good discrimination (area under the curve 0.77) for 1-year mortality. Addition of 3 biomarkers (tumor necrosis factor α receptor II, pro-brain natriuretic peptide, and cardiac troponin T) further improved model discrimination to 0.82. Patients with 0-1, 2-3, 4-6, or 7-9 risk factors had 1-year mortality rates of 0.8%, 2.7%, 16.1%, and 46.2%, respectively. CONCLUSION Individuals with more comorbidities and elevation of specific serum biomarkers were at increased risk of all-cause mortality despite being deemed as having a reasonable 1-year life expectancy. A simple risk score composed of readily available clinical data and serum biomarkers may better identify patients at high risk of early mortality and improve patient selection and counseling for primary prevention ICD therapy.

Mild-to-moderate kidney dysfunction and the risk of sudden cardiac death in the setting of acute myocardial infarction

BACKGROUND Although end-stage renal disease is known to elevate the risk of sudden cardiac death (SCD), the role of less severe renal impairment in SCD is unclear. OBJECTIVE The purpose of this study was to examine the association between mild-to-moderate renal impairment and first ischemic ventricular fibrillation (VF). METHODS Renal function in patients included in the Arrhythmia Genetics in the NEtherlands Study (AGNES) were compared. Cases (n = 337, age 56 ± 1 year, 80% men) were defined as patients who had survived VF at the time of their first acute ST elevation myocardial infarction (STEMI), and controls (n = 339, age 58 ± 1 years, 80% men) were defined as those without VF during their first acute STEMI. Estimated glomerular filtration rate (eGFR) at the time of acute STEMI was computed using the 4-variable Modification of Diet in Renal Disease equation. RESULTS At eGFR less than 105 mL/min, a decrease in eGFR was associated with elevated odds of developing VF during STEMI. The association was essentially flat at eGFR levels >105 mL/min. The lowest eGFR quintile was associated with a >6-fold increase in odds of developing VF compared to the fourth quintile. This association between eGFR and VF at the time of STEMI remained significant after adjusting for potential confounders including electrolyte levels. CONCLUSION Mild-to-moderate kidney dysfunction is associated with a significantly elevated risk of VF in the setting of acute STEMI. Further studies are needed to investigate the precise mechanisms by which mild kidney function results in VF.

Midterm Safety and Performance of a Leadless Cardiac Pacemaker: 3-Year Follow-up to the LEADLESS Trial (Nanostim Safety and Performance Trial for a Leadless Cardiac Pacemaker System)

Leadless cardiac pacemakers (LCPs) have been introduced to decrease lead- and pocket-related complications. Initial studies have shown short-term complication rates of 4% to 6.7% and adequate electric performance in up to 12 months of follow-up.1–3 However, to fully appreciate the clinical impact and the robustness of this novel technology, additional follow-up is required to determine the long-term safety and performance. In this study, we report the longest clinical follow-up to date: the 3-year results of the LEADLESS trial (Nanostim Safety and Performance Trial for a Leadless Cardiac Pacemaker System).4 Patients implanted with an LCP (Nanostim, St. Jude Medical/Abbott) were retrospectively assessed to evaluate the safety and performance of this device with a minimum of 3 years of follow-up. No patients were lost to follow-up. Medical records were analyzed from June 2014 until May 2016 and evaluated for (1) serious adverse device effects (SADEs) and (2) electric performance of the LCP. The primary outcome was freedom from SADEs (Kaplan-Meier estimate) at 40 months of follow-up. Categorical variables are presented as frequencies and continuous variables as means (±SD). Permission of the local institutional review boards was obtained for this retrospective analysis, and all participants gave written informed consent. Thirty-three patients (age 77±8 years, 67% male) were enrolled and were followed for a median duration of 38 months (range, 21–41 months). Two patients were …

A leadless solution

A 78-year-old male with a history of complicated diabetes, peripheral arterial and coronary disease, hypertension, and atrial fibrillation with a VVI pacemaker was referred to our tertiary centre with a bilateral pocket infection. Management of this infection was suboptimal and not according to the current guidelines. The initial left-sided …

Successful replacement of the longest worldwide in situ Nanostim leadless cardiac pacemaker for a Micra Transcatheter Pacing System

The potential inability to retrieve chronically implanted leadless pacemakers (LP) at end-of-life limits the application of this novel technology. Data on safe long-term LP retrieval is lacking, yet is of paramount importance. We present the case of an 80-year-old patient in whom a Nanostim LP was successfully implanted for chronic atrial fibrillation with symptomatic slow ventricular response in January 2013. Background history was notable for rheumatic aortic and mitral stenosis and status post mechanical aortic and mitral valve replacement. At a regular follow-up visit 4 years and 9 months after LP implantation, the initial normal communication with the device was lost during impedance measurement, a known trigger for battery failure. The patient had 73% right ventricular pacing. Strategies to replace LPs reaching end of service remain an unsettled concern. Suggested strategies comprise the following: placing an additional leadless device adjacent to the LP or retrieving the non-functioning LP and subsequently implanting a new device. We decided to extract the LP in order to limit the amount of non-functioning intracardiac hardware and mitigate the potential device-device interference and unknown long-term risks of multiple intracardiac devices. In addition, retrieval may result in a more accessible right ventricle (RV) in case re-implantation of a new device is indicated. The procedure was performed in the catheterization laboratory under fluoroscopic guidance and local anesthesia (Fig. 1). The retrieval catheter (Abbott) was percutaneously introduced via the femoral vein by using a 27 French introducer sheath (Medtronic). The single-loop snare and the integrated protective sleeve at the end of the retrieval catheter were engaged towards the RV. The snare was engaged to capture the distal cap of the device. After docking the device, the helix was unscrewed from the endocardium. The protective sleeve was advanced over the LP and subsequently the device was removed. A Micra Transcatheter Pacing System (TPS) was inserted by the catheter delivery system (Medtronic) through the right femoral vein with the use of the same 27 French introducer (Medtronic). The Micra TPS was fixated to the myocardium in the RVapex at a more septal position. The Micra TPS implantation was completed without complications and with stable electrical parameters (i.e., RV sensing of > 20 mV, impedance of 740 Ω and a pacing threshold of 0.38 Volts at 0.24 ms). Histopathological examination showed minimal adherent fibrous tissue at the proximal docking feature and helix of the Nanostim. We showed a safe and easy extraction of the longest worldwide in situ Nanostim. The feasibility of chronic uneventful LP retrievals, if confirmed by subsequent trials or follow-up studies, will demonstrate that there is an effective end-of-life device strategy, which makes LP therapy a viable alternative to standard lead-based pacing. Considering the increasing incidence of patients in whom the Nanostim battery fails to meet their projected longevity, this information is highly relevant for all physicians implanting these devices. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10840-017-0310-2) contains supplementary material, which is available to authorized users.