Implantation of a leadless pacemaker in young adults.

AIMS: Leadless pacing has emerged as an alternative to conventional transvenous pacemakers to mitigate the risks of pocket- and lead-related complications but its use remains controversial in young adults mostly because experience in this patient population is limited. We sought to examine the feasibility and safety of implanting leadless single chamber pacemakers in young adults. METHODS: This multicenter, retrospective, observational study sought to evaluate the safety, efficacy, and electrical performance of the Micra VR Transcatheter Pacemaker System (Medtronic) in patients between 18 and 40 years who underwent implantation of a leadless pacemaker for any indication at the university medical centers of Bordeaux, Clermont-Ferrand, Toulouse, and Tours (France), between 2015 and 2021. The primary safety endpoint was freedom from system-related or procedure-related major complications at 6 months. The primary efficacy endpoint was the combination of a low (≤2 V) and stable (increase within 1.5 V) pacing capture threshold at 6 months. RESULTS: Leadless pacemaker implantation was successful in all 35 patients. At 6 months, safety endpoint was met for 35 (100%) and efficacy endpoint for 34 (97%) patients. During a follow-up of 26 ± 15 months (range: 6-60 months), Safety endpoint remained 100% and efficacy endpoint was 94%. Leadless pacemaker retrieval was not required in any patient. Approximately one-third of patients (n = 13, 37%) had >40% ventricular pacing burdens at 1 year, including all 10 patients with a complete AV block but also 3 patients with normal AV conduction during implantation. One patient reported symptoms of pacemaker syndrome which was confirmed using Holter recording and successfully treated using reprogramming. CONCLUSION: In this observational study, leadless pacemakers demonstrated favorable short- and intermediate-term safety and effectiveness in young adults.

Leadless pacemakers in critically ill patients requiring prolonged cardiac pacing: A multicenter international study.

BACKGROUND: Temporary transvenous pacing in critically ill patients requiring prolonged cardiac pacing is associated with a high risk of complications. We sought to evaluate the safety and efficacy of self-contained intracardiac leadless pacemaker (LPM) implantation in this population. METHODS AND RESULTS: Consecutive patients implanted with a Micra LPM during the hospitalization in an intensive care unit were retrospectively included. Inclusion criteria were: more than or equal to 1 supracaval central venous line, or a ventilation tube, or intravenous antibiotic therapy for ongoing sepsis or bacteremia. Patients with a history of the previous implantation of a pacemaker were excluded. Out of 1016 patients implanted with an LPM, 99 met the inclusion criteria. Mean age was 75 years and Charlson comorbidity index 7. LPM implantation was successfully performed in 98% of cases, with a perioperative complication rate of 5%, mainly cardiac injuries. In-hospital mortality rate was 6%. No late (>30 days) device-related complication occurred, especially no infection. CONCLUSIONS: LPM appears as an acceptable alternative to conventional temporary transvenous pacing in selected critically ill patients requiring prolonged cardiac pacing, especially regarding the risk of infection.

Behavior of AV synchrony pacing mode in a leadless pacemaker during variable AV conduction and arrhythmias.

INTRODUCTION: MARVEL 2 assessed the efficacy of mechanical atrial sensing by a ventricular leadless pacemaker, enabling a VDD pacing mode. The behavior of the enhanced MARVEL 2 algorithm during variable atrio-ventricular conduction (AVC) and/or arrhythmias has not been characterized and is the focus of this study. METHODS: Of the 75 patients enrolled in the MARVEL 2 study, 73 had a rhythm assessment and were included in the analysis. The enhanced MARVEL 2 algorithm included a mode-switching algorithm that automatically switches between VDD and ventricular only antibradycardia pacing (VVI)-40 depending upon AVC status. RESULTS: Forty-two patients (58%) had persistent third degree AV block (AVB), 18 (25%) had 1:1 AVC, 5 (7%) had variable AVC status, and 8 (11%) had atrial arrhythmias. Among the 42 patients with persistent third degree AVB, the median ventricular pacing (VP) percentage was 99.9% compared to 0.2% among those with 1:1 AVC. As AVC status changed, the algorithm switched to VDD when the ventricular rate dropped less than 40 bpm. During atrial fibrillation (AF) with ventricular response greater than 40 bpm, VVI-40 mode was maintained. No pauses longer than 1500 ms were observed. Frequent ventricular premature beats reduced the percentage of AV synchrony. During AF, the atrial signal was of low amplitude and there was infrequent sensing. CONCLUSION: The mode switching algorithm reduced VP in patients with 1:1 AVC and appropriately switched to VDD during AV block. No pacing safety issues were observed during arrhythmias.

Wearable cardioverter-defibrillator in patients with a transient risk of sudden cardiac death: the WEARIT-France cohort study.

AIMS: We aimed to provide contemporary real-world data on wearable cardioverter-defibrillator (WCD) use, not only in terms of effectiveness and safety but also compliance and acceptability. METHODS AND RESULTS: Across 88 French centres, the WEARIT-France study enrolled retrospectively patients who used the WCD between May 2014 and December 2016, and prospectively all patients equipped for WCD therapy between January 2017 and March 2018. All patients received systematic education session through a standardized programme across France at the time of initiation of WCD therapy and were systematically enrolled in the LifeVest Network remote services. Overall, 1157 patients were included (mean age 60 ± 12 years, 16% women; 46% prospectively): 82.1% with ischaemic cardiomyopathy, 10.3% after implantable cardioverter-defibrillator explant, and 7.6% before heart transplantation. Median WCD usage period was 62 (37-97) days. Median daily wear time of WCD was 23.4 (22.2-23.8) h. In multivariate analysis, younger age was associated with lower compliance [adjusted odds ratio (OR) 0.97, 95% confidence interval (CI) 0.95-0.99, P < 0.01]. A total of 18 participants (1.6%) received at least one appropriate shock, giving an incidence of appropriate therapy of 7.2 per 100 patient-years. Patient-response button allowed the shock to be aborted in 35.7% of well-tolerated sustained ventricular arrhythmias and in 95.4% of inappropriate ventricular arrhythmia detection, finally resulting in an inappropriate therapy in eight patients (0.7%). CONCLUSION: Our real-life findings reinforce previous studies on the efficacy and safety of the WCD in the setting of transient high-risk group in selected patients. Moreover, they emphasize the fact that when prescribed appropriately, in concert with adequate patient education and dedicated follow-up using specific remote monitoring system, compliance with WCD is high and the device well-tolerated by the patient.

Exploring a New Systematic Route for Left Ventricular Pacing in Cardiac Resynchronization Therapy.

BACKGROUND: Frequency and distribution of left ventricular (LV) venous collaterals were studied in vivo to evaluate the ease and feasibility of implanting a new ultra-thin LV quadripolar microlead for cardiac resynchronization therapy (CRT).Methods and Results:Evaluable venograms were analyzed to define the prevalence of venous collaterals (>0.5 mm diameter) between: (1) different LV segments; and (2) different major LV veins in: unselected patients who underwent CRT from 2008 to 2012 at Rouen Hospital, France (retrospective); and CRT patients from the Axone Acute pilot study in 2018 (prospective). In prospective patients with evaluable venograms, LV microlead implantation was attempted. Thirty-six (21/65 retrospective, 15/20 prospective) patients had evaluable venograms with ≥1 visible venous collaterals. Collaterals were found between LV veins in all CRT patients with evaluable venograms. Regionally, prevalence was highest between: the apical inferior and apical lateral (42%); and mid inferior and mid inferolateral (42%) segments. Collateral connections were most prevalent between: the inferior interventricular vein (IIV) and lateral vein (64% [23/36]); and IIV and infero-lateral vein (36% [13/36]). Cross-vein microlead implantation was possible in 18 patients (90%), and single-vein implantation was conducted in the other 2 patients (10%). CONCLUSIONS: Venous collaterals were found in vivo between LV veins in all CRT patients with evaluable venograms, making this network an option for accessing multiple LV sites using a single LV microlead.

Electrogram morphology discriminators in implantable cardioverter defibrillators: A comparative evaluation.

BACKGROUND: Morphology algorithms are currently recommended as a standalone discriminator in single-chamber implantable cardioverter defibrillators (ICDs). However, these proprietary algorithms differ in both design and nominal programming. OBJECTIVE: To compare three different algorithms with nominal versus advanced programming in their ability to discriminate between ventricular (VT) and supraventricular tachycardia (SVT). METHODS: In nine European centers, VT and SVTs were collected from Abbott, Boston Scientific, and Medtronic dual- and triple-chamber ICDs via their respective remote monitoring portals. Percentage morphology matches were recorded for selected episodes which were classified as VT or SVT by means of atrioventricular comparison. The sensitivity and related specificity of each manufacturer discriminator was determined at various values of template match percentage from receiving operating characteristics (ROC) curve analysis. RESULTS: A total of 534 episodes were retained for the analysis. In ROC analyses, Abbott Far Field MD (area under the curve [AUC]: 0.91; P < .001) and Boston Scientific RhythmID (AUC: 0.95; P < .001) show higher AUC than Medtronic Wavelet (AUC: 0.81; P < .001) when tested for their ability to discriminate VT from SVT. At nominal % match threshold all devices provided high sensitivity in VT identification, (91%, 100%, and 90%, respectively, for Abbott, Boston Scientific, and Medtronic) but contrasted specificities in SVT discrimination (85%, 41%, and 62%, respectively). Abbott and Medtronic's nominal thresholds were similar to the optimal thresholds. Optimization of the % match threshold improved the Boston Scientific specificity to 79% without compromising the sensitivity. CONCLUSION: Proprietary morphology discriminators show important differences in their ability to discriminate SVT. How much this impact the overall discrimination process remains to be investigated.

Impact of paced left ventricular dyssynchrony on left ventricular reverse remodeling after cardiac resynchronization therapy.

INTRODUCTION: We investigated whether pacing-induced electrical dyssynchrony at the time of cardiac resynchronization therapy (CRT) device implantation was associated with chronic CRT response. METHODS AND RESULTS: We included a total of 69 consecutive heart failure patients who received a CRT device. Left (LVp-RVs) and right (RVp-LVs) pacing-induced interlead delays were measured intraoperatively and used to determine if there was paced left ventricular (LV) dyssynchrony, defined as present when LVp-RVs is larger than RVp-LVs. CRT response was defined as a reduction in LV end-systolic volume ≥15%, 6 months after implantation. Paced left ventricular dyssynchrony (PLVD) was associated with ischemic cardiomyopathy (ICM) (χ2 : 8; P = .005) but not with QRS morphology nor with pacing lead positions. In a univariate analysis, PLVD (odds ratio [OR], 6.53; 95% confidence interval [CI], 2.2-18.9; P = .001), atypical left bundle branch block (LBBB) (OR, 3.3; 95% CI, 1.2-9.4; P = .022), and ICM (OR, 5.2; 95% CI, 1.6-17; P = .006) were associated with nonresponse. In a multivariate analysis, both PLVD (OR, 9.74; 95% CI, 2.8-33.9; P < .0001) and atypical LBBB (OR, 5.6; 95% CI, 1.5-20.3; P = .009) were independently associated with nonresponse. Adding PLVD to a model based on QRS morphology provided a significant and meaningful incremental value to predict LV reverse remodeling after CRT (χ2 to enter: 8; P < .005). Computer simulations corroborate these findings by showing that, while intrinsic electrical dyssynchrony is a prerequisite, the level of pacing-induced dyssynchrony modulates acute CRT response. CONCLUSION: In addition to the intrinsic electrical substrate, PLVD is strongly associated with less LV reverse remodeling, demonstrating that measuring the electrical substrate during pacing has additional value for prediction of CRT response in an already well-selected patient population.

Prognostic value of the 12-lead surface electrocardiogram in sarcomeric hypertrophic cardiomyopathy: data from the REMY French register.

AIMS: To identify independent electrocardiogram (ECG) predictors of long-term clinical outcome based on standardized analysis of the surface ECG in a large multicentre cohort of patients with sarcomeric hypertrophic cardiomyopathy (HCM). METHODS AND RESULTS: Retrospective observational study from the REMY French HCM clinical research observatory. Primary endpoint was a composite of all-cause mortality, major non-fatal arrhythmic events, hospitalization for heart failure (HF), and stroke. Secondary endpoints were components of the primary endpoint. Uni- and multivariable Cox proportional hazard regression analysis was performed to identify independent predictors. Among 994 patients with HCM, only 1.8% had a strictly normal baseline ECG. The most prevalent abnormalities were inverted T waves (63.7%), P-wave abnormalities (30.4%), and abnormal Q waves (25.5%). During a mean follow-up of 4.0 ± 2.0 years, a total of 272 major cardiovascular events occurred in 217 patients (21.8%): death or heart transplant in 98 (9.8%), major arrhythmic events in 40 (4.0%), HF hospitalization in 115 (11.6%), and stroke in 23 (2.3%). At multivariable analysis using ECG covariates, prolonged QTc interval, low QRS voltage, and PVCs of right bundle branch block pattern predicted worse outcome, but none remained independently associated with the primary endpoint after adjustment on main demographic and clinical variables. For secondary endpoints, abnormal Q waves independently predicted all-cause death [hazard ratio (HR) 2.35, 95% confidence interval (CI) 1.23-4.47; P = 0.009] and prolonged QTc the risk of HF hospitalization (HR 1.006, 95% CI 1.001-1.011; P = 0.024). CONCLUSION: The 12-lead surface ECG has no independent value to predict the primary outcome measure in patients with HCM. The 12-lead surface ECG has been widely used as a screening tool in HCM but its prognostic value remains poorly known. The value of baseline surface ECG to predict long-term clinical outcomes was studied in a cohort of 994 patients with sarcomeric HCM. The surface ECG has no significant additional value to predict outcome in this patient population.

Causes of impaired biventricular pacing in cardiac resynchronization devices with left ventricular sensing.

BACKGROUND: Loss of biventricular stimulation can result in nonresponse to cardiac resynchronization therapy (CRT). Problems associated with the left ventricular (LV) lead and LV sensing can be challenging to detect and their incidence is unclear. The purpose of this study was to investigate mechanisms of loss of biventricular pacing due to LV lead- and LV sensing-associated problems. METHODS: In this bicentric study, CRT patients were surveilled using a novel remote monitoring algorithm from Biotronik (Germany) that registers LV electrograms (EGMs) during intermittent loss of resynchronization. The episodes were analyzed to assess the mechanisms of resynchronization interruptions. RESULTS: We analyzed 582 EGMs from 61 patients. During a median follow-up of 6 months, 59% of the patients had such episodes. The majority of the episodes (61%) were related to inappropriate inhibition of LV pacing, mostly due to upper rate lock-in caused by LV sensing (58%). In contrast, 8% of episodes showed intermittent loss of LV capture, which was identified thanks to LV sensing. The remaining 31% of episodes were due to physiological reasons for resynchronization interruptions (eg, supraventricular tachycardia [18%], premature beats [8%], and others [5%]). Patients with CRT interruption episodes had lower resynchronization rates (median: 98.5% vs 100%, P = .044). CONCLUSIONS: Inadequate programming (active LV sensing with T-wave protection) is the main cause of impaired resynchronization in devices with LV sensing. In general, we recommend the deactivation of the LV T-wave protection function.

Dynamic atrioventricular delay programming improves ventricular electrical synchronization as evaluated by 3D vectorcardiography.

BACKGROUND: Optimal timing of the atrioventricular delay in cardiac resynchronization therapy (CRT) can improve synchrony in patients suffering from heart failure. The purpose of this study was to evaluate the impact of SyncAV™ on electrical synchrony as measured by vectorcardiography (VCG) derived QRS metrics during bi-ventricular (BiV) pacing. METHODS: Patients implanted with a cardiac resynchronization therapy (CRT) device and quadripolar left ventricular (LV) lead underwent 12­lead ECG recordings. VCG metrics, including QRS duration (QRSd) and area, were derived from the ECG by a blinded observer during: intrinsic conduction, BiV with nominal atrioventricular delays (BiV Nominal), and BiV with SyncAV programmed to the optimal offset achieving maximal synchronization (BiV + SyncAV Opt). RESULTS: One hundred patients (71% male, 40% ischemic, 65% LBBB, 32 ±â€¯9% ejection fraction) completed VCG assessment. QRSd during intrinsic conduction (166 ±â€¯25 ms) was narrowed successively by BiV Nominal (137 ±â€¯23 ms, p < .05 vs. intrinsic) and BiV + SyncAV Opt (122 ±â€¯22 ms, p < .05 vs. BiV Nominal). Likewise, 3D QRS area during intrinsic conduction (90 ±â€¯42 mV ∗ ms) was reduced by BiV Nominal (65 ±â€¯39 mV ∗ ms, p < .05 vs. intrinsic) and further by BiV + SyncAV Opt (53 ±â€¯30 mV ∗ ms, p = .06 vs. BiV Nominal). CONCLUSION: With VCG-based, patient-specific optimization of the programmable offset, SyncAV reduced electrical dyssynchrony beyond conventional CRT.

A Leadless Intracardiac Transcatheter Pacing System.

BACKGROUND: A leadless intracardiac transcatheter pacing system has been designed to avoid the need for a pacemaker pocket and transvenous lead. METHODS: In a prospective multicenter study without controls, a transcatheter pacemaker was implanted in patients who had guideline-based indications for ventricular pacing. The analysis of the primary end points began when 300 patients reached 6 months of follow-up. The primary safety end point was freedom from system-related or procedure-related major complications. The primary efficacy end point was the percentage of patients with low and stable pacing capture thresholds at 6 months (≤2.0 V at a pulse width of 0.24 msec and an increase of ≤1.5 V from the time of implantation). The safety and efficacy end points were evaluated against performance goals (based on historical data) of 83% and 80%, respectively. We also performed a post hoc analysis in which the rates of major complications were compared with those in a control cohort of 2667 patients with transvenous pacemakers from six previously published studies. RESULTS: The device was successfully implanted in 719 of 725 patients (99.2%). The Kaplan-Meier estimate of the rate of the primary safety end point was 96.0% (95% confidence interval [CI], 93.9 to 97.3; P<0.001 for the comparison with the safety performance goal of 83%); there were 28 major complications in 25 of 725 patients, and no dislodgements. The rate of the primary efficacy end point was 98.3% (95% CI, 96.1 to 99.5; P<0.001 for the comparison with the efficacy performance goal of 80%) among 292 of 297 patients with paired 6-month data. Although there were 28 major complications in 25 patients, patients with transcatheter pacemakers had significantly fewer major complications than did the control patients (hazard ratio, 0.49; 95% CI, 0.33 to 0.75; P=0.001). CONCLUSIONS: In this historical comparison study, the transcatheter pacemaker met the prespecified safety and efficacy goals; it had a safety profile similar to that of a transvenous system while providing low and stable pacing thresholds. (Funded by Medtronic; Micra Transcatheter Pacing Study ClinicalTrials.gov number, NCT02004873.).

Left ventricular sensing in cardiac resynchronization devices-opportunities and pitfalls for device programming.

INTRODUCTION: Some cardiac resynchronization therapy (CRT) device manufacturers (Biotronik, Germany; Boston Scientific, United States) have implemented left ventricular (LV) sensing functionality to prevent pacing into the vulnerable phase. Physicians are only partially aware of programming pitfalls related to LV sensing and general programming advice is lacking. METHODS AND RESULTS: We provide an illustrative case-series-based review of the variety of potential problems with LV sensing. LV sensing may inappropriately impair CRT delivery due to LV-sensing issues or improper device programming. This can cause beat-wise loss of resynchronization but also ongoing desynchronization. On the other hand, LV sensing provides additional diagnostic information, which may reveal intermittent problems of the LV lead such as capture loss. We summarize the available evidence to provide manufacturer-specific recommendations on device programming and troubleshooting for daily clinical practice. CONCLUSION: CRT devices with LV sensing may suffer from impaired resynchronization due to programming pitfalls. If LV sensing is active (nominal setting in Biotronik and Boston Scientific devices), careful lookout for related problems and resynchronization percentage is required. Optimization is mandatory and even deactivation of LV sensing may have to be considered.

Role of medical reaction in management of inappropriate ventricular arrhythmia diagnosis: the inappropriate Therapy and HOme monitoRiNg (THORN) registry.

AIMS: Implantable cardioverter-defibrillators (ICDs) reduce sudden cardiac death in selected patients but inappropriate ICD shocks have been associated with increased mortality. The THORN registry aims to describe the rate of inappropriate ventricular arrhythmia diagnoses and therapies in patients followed by remote monitoring, as well as the following delay to next patient contact (DNPC). METHODS AND RESULTS: One thousand eight hundred and eighty-two patients issued from a large remote monitoring database first implanted with an ICD for primary or secondary prevention in 110 French hospitals from 2007 to 2014 constitute the THORN population. Among them, 504 patients were additionally followed prospectively for evaluation of the DNPC. Eight hundred and ninety-five out of 1551 (58%) patients had ischaemic heart disease and 358/771 (46%) were implanted for secondary prevention. During 13.7 ± 3.4 months of follow-up, the prevalence of first inappropriate diagnosis in a ventricular arrhythmia zone with enabled therapy was 162/1882 (9%). Among those patients, 122/162 (75%) suffered at least one inappropriate therapy and 58/162 (36%) at least one inappropriate shock. Eighty-three out of 162 (51%) of first inappropriate diagnosis occurred during the first 4 months following implantation. The median DNPC was 8 days (interquartile range 1-26). At least one other day with recording of an inappropriate diagnosis of the same cause occurred in 13/43 (30%) of available DNPC periods, with an inappropriate therapy in 7/13 (54%). CONCLUSION: Inappropriate diagnoses occurred in 9% of patients implanted with an ICD during the first 14 months. The DNPC after inadequate ventricular arrhythmia diagnoses remains long in daily practice and should be optimized. CLINICALTRIALS.GOV IDENTIFIER: NCT01594112.

Patient selection, pacing indications, and subsequent outcomes with de novo leadless single-chamber VVI pacing.

AIMS: Patient selection is a key component of securing optimal patient outcomes with leadless pacing. We sought to describe and compare patient characteristics and outcomes of Micra patients with and without a primary pacing indication associated with atrial fibrillation (AF) in the Micra IDE trial. METHODS AND RESULTS: The primary outcome (risk of cardiac failure, pacemaker syndrome, or syncope related to the Micra system or procedure) was compared between successfully implanted patients from the Micra IDE trial with a primary pacing indication associated with AF or history of AF (AF group) and those without (non-AF group). Among 720 patients successfully implanted with Micra, 228 (31.7%) were in the non-AF group. Reasons for selecting VVI pacing in non-AF patients included an expectation for infrequent pacing (66.2%) and advanced age (27.2%). More patients in the non-AF group had a condition that precluded the use of a transvenous pacemaker (9.6% vs. 4.7%, P = 0.013). Atrial fibrillation patients programmed to VVI received significantly more ventricular pacing compared to non-AF patients (median 67.8% vs. 12.6%; P < 0.001). The overall occurrence of the composite outcome at 24 months was 1.8% with no difference between the AF and non-AF groups (hazard ratio 1.36, 95% confidence interval 0.45-4.2; P = 0.59). CONCLUSION: Nearly one-third of patients selected to receive Micra VVI therapy were for indications not associated with AF. Non-AF VVI patients required less frequent pacing compared to patients with AF. Risks associated with VVI therapy were low and did not differ in those with and without AF.

Behavior of leadless AV synchronous pacing during atrial arrhythmias and stability of the atrial signals over time-Results of the MARVEL Evolve subanalysis.

INTRODUCTION: The MARVEL study demonstrated at a single time point that accelerometer (ACC)-based atrial sensing improves atrioventricular (AV) synchrony (AVS) in patients with AV block and a Micra pacemaker (Medtronic, Minneapolis, MN, USA). The purpose of the MARVEL Evolve substudy was to assess the performance over time. METHODS: This prospective single-center study compared AVS and ACC signals at two visits ≥6 months apart. Custom software was temporarily downloaded into the Micra at each visit and AVS was measured during 30 min at rest. RESULTS: Nine patients from the MARVEL study were enrolled. The mean (±standard deviation) age was 82.3 ± 6.0 years old, 67% were male, and a Micra was implanted for 6.0 ± 6.4 months. High-degree AV block was present in four patients, whereas five with predominantly intrinsic conduction required intermittent pacing for bradycardia. The mean interval between visits was 7.1 ± 0.6 months. Seven patients had normal sinus node function at both visits and were included in a paired analysis. Both ACC signal amplitude (visit 2-visit 1 = 1.4 mG; 95% confidence interval [CI] [-25.8 to 28.4 mG]; P = 0.933) and AVS (visit 1: 90.8%, 95% CI [72.4, 97.4] and visit 2: 91.4%, 95% CI [63.8, 98.5]; P = 0.740) remained stable. Three patients had spontaneous atrial tachycardia. During atrial fibrillation, no atrial contraction was detected or tracked. During atrial flutter, intermittent tracking resulted in a ventricular rate of 60 ± 8 beats per minute (bpm); there was no ventricular pacing >100 bpm. CONCLUSION: ACC signals amplitude and performance of AVS pacing were stable over time. During atrial arrhythmias, the AV synchronous pacing mode behaved safely.

Incidence and outcomes of systemic infections in patients with leadless pacemakers: Data from the Micra IDE study.

BACKGROUND: The Micra clinical trials have enrolled more than 2500 patients without any reported device-related infections that required removal during follow-up. Leadless pacemakers might be more resistant to bacterial seeding due to smaller surface area and a greater tendency for encapsulation. OBJECTIVE: To analyze the incidence and outcomes of serious infectious events (SIEs: bacteremia or endocarditis) that developed during follow-up in patients with history of Micra leadless pacemaker implantation. METHODS: SIE and outcomes were characterized based upon adverse event reports. Among 720 patients implanted with Micra in the investigational device exemption trial, we identified 16 patients who had documented 21 SIEs during follow-up. RESULTS: Among patients with SIEs, mean age was 71.9 ± 11.7 years. SIEs occurred at a mean 4.8 ± 4.5 months after implant and patients were followed for 13.1 ± 9.1 months after documentation of SIE. All events were adjudicated as unrelated to the Micra device or procedure. Bacteremia was documented to be related to a gram-positive organism in 13 events (seven Staphylococcus, three Streptococcus, two Enterococcus, and one uncharacterized gram-positive bacteria), and gram-negative organisms in three events. In five events, the type of organism was not characterized (two patients with endocarditis). No persistent cases of bacteremia after antibiotic cessation were seen over the duration of follow-up CONCLUSION: In this small series of Micra patients who developed SIEs postimplant, the occurrence of bacteremia and/or endocarditis did not appear to lead to persistent bacteremia off antibiotics; most events resolved with antibiotic treatment.

Towards eradication of inappropriate therapies for ICD lead failure by combining comprehensive remote monitoring and lead noise alerts.

INTRODUCTION: Recognition of implantable cardioverter defibrillator (ICD) lead malfunction before occurrence of life threatening complications is crucial. We aimed to assess the effectiveness of remote monitoring associated or not with a lead noise alert for early detection of ICD lead failure. METHODS: From October 2013 to April 2017, a median of 1,224 (578-1,958) ICD patients were remotely monitored with comprehensive analysis of all transmitted materials. ICD lead failure and subsequent device interventions were prospectively collected in patients with (RMLN) and without (RM) a lead noise alert (Abbott Secure Sense™ or Medtronic Lead Integrity Alert™) in their remote monitoring system. RESULTS: During a follow-up of 4,457 patient years, 64 lead failures were diagnosed. Sixty-one (95%) of the diagnoses were made before any clinical complication occurred. Inappropriate shocks were delivered in only one patient of each group (3%), with an annual rate of 0.04%. All high voltage conductor failures were identified remotely by a dedicated impedance alert in 10 patients. Pace-sense component failures were correctly identified by a dedicated alert in 77% (17 of 22) of the RMLN group versus 25% (8 of 32) of the RM group (P = 0.002). The absence of a lead noise alert was associated with a 16-fold increase in the likelihood of initiating either a shock or ATP (OR: 16.0, 95% CI 1.8-143.3; P = 0.01). CONCLUSION: ICD remote monitoring with systematic review of all transmitted data is associated with a very low rate of inappropriate shocks related to lead failure. Dedicated noise alerts further reduce inappropriate detection of ventricular arrhythmias.

Health-related quality of life impact of a transcatheter pacing system.

BACKGROUND: Transcatheter pacing systems (TPS) provide a novel, minimally invasive approach in which a miniaturized, leadless pacemaker (PM) is transfemorally implanted in the right ventricle. We evaluated the health-related quality of life (HRQoL) impact, patient satisfaction, and activity restrictions following TPS in a large prospective multicenter clinical trial. METHODS AND RESULTS: Patients who underwent a Micra TPS implantation between December 2013 and May 2015 were included. HRQoL impact was evaluated using the Short-Form-36 (SF-36) questionnaire at baseline, 3, and 12 months. Patient satisfaction was assessed using a three-item questionnaire determining recovery, activity level, and esthetic appearance at 3 months. Implanting physicians compared the patient activity restrictions for TPS to traditional PM therapy. A total of 720 patients were implanted with a TPS (76 ± 11 years; 59% male). Of these patients, 702 (98%), 681 (95%), and 635 (88%) completed the SF-36 at baseline, 3 and 12 months, respectively. Improvements were observed at 3 and 12 months in all SF-36 domains and all attained statistical significance. Of 693 patients who completed the patient satisfaction questionnaire, 96%, 91%, 74% were (very) satisfied with their esthetic appearance, recovery, and level of activity, respectively. TPS discharge instructions were rated less restrictive in 49%, equally restrictive in 47%, and more restrictive in 4% of cases compared with traditional PM systems. CONCLUSIONS: TPS resulted in postimplant HRQoL improvements at 3 and 12 months, and high levels of patient satisfaction at 3 months. Further, TPS was associated with less activity restrictions compared with traditional PM systems.

Transient under-sensing of the ventricular lead during abdominal ultrasound as cause of ventricular fibrillation.

Pacemaker-induced arrhythmias represent a very rare complication. Algorithm-induced ventricular tachycardias have been described but this report is the first to describe a ventricular fibrillation caused by transient undersensing of the ventricular lead during an abdominal ultrasound.

Contractility sensor-guided optimization of cardiac resynchronization therapy: results from the RESPOND-CRT trial.

AIMS: Although cardiac resynchronization therapy (CRT) is effective in patients with systolic heart failure (HF) and a wide QRS interval, a substantial proportion of patients remain non-responsive. The SonR contractility sensor embedded in the right atrial lead enables individualized automatic optimization of the atrioventricular (AV) and interventricular (VV) timings. The RESPOND-CRT study investigated the safety and efficacy of the contractility sensor system in HF patients undergoing CRT. METHODS AND RESULTS: RESPOND-CRT was a prospective, randomized, double-blinded, multicentre, non-inferiority trial. Patients were randomized (2:1, respectively) to receive weekly, automatic CRT optimization with SonR vs. an Echo-guided optimization of AV and VV timings. The primary efficacy endpoint was the rate of clinical responders (patients alive, without adjudicated HF-related events, with improvement in New York Heart Association class or quality of life), at 12 months. The study randomized 998 patients. Responder rates were 75.0% in the SonR arm and 70.4% in the Echo arm (mean difference, 4.6%; 95% CI, -1.4% to 10.6%; P < 0.001 for non-inferiority margin -10.0%) (Table 2). At an overall mean follow-up of 548 ± 190 days SonR was associated with a 35% risk reduction in HF hospitalization (hazard ratio, 0.65; 95% CI, 0.46-0.92; log-rank P = 0.01). CONCLUSION: Automatic AV and VV optimization using the contractility sensor was safe and as effective as Echo-guided AV and VV optimization in increasing response to CRT. CLINICALTRIALS.GOV NUMBER: NCT01534234.