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Background To which extent atrial remodeling occurs before atrial fibrillation (AF) is unknown. Objective The PREventive left atrial appenDage resection for the predICtion of fuTure Atrial Fibrillation (PREDICT-AF) study investigated such subclinical remodeling, which may be used for risk stratification and AF prevention. Methods Patients (N = 150) without a history of AF with a CHA2DS2-VASc score of ≥2 at an increased risk of developing AF were included. The left atrial appendage was excised and blood samples were collected during elective cardiothoracic surgery for biomarker discovery. Participants were followed for 2 years with Holter monitoring to determine any atrial tachyarrhythmia after a 50-day blanking period. Results Eighteen patients (12%) developed incident AF, which was associated with increased tissue gene expression of collagen I (COL1A1), collagen III (COL3A1), and collagen VIII (COL8A2), tenascin-C (TNC), thrombospondin-2 (THBS2), and biglycan (BGN). Furthermore, the fibroblast activating endothelin-1 (EDN1) and sodium voltage-gated channel β subunit 2 (SCN2B) were associated with incident AF whereas the Kir2.1 channel (KCNJ2) tended to downregulate. The plasma levels of COL8A2 and TNC correlated with tissue expression and predicted incident AF. A gene panel including tissue KCNJ2, COL1A1, COL8A2, and EDN1 outperformed clinical prediction models in discriminating incident AF. Conclusion The PREDICT-AF study demonstrates that atrial remodeling occurs long before incident AF and implies future potential for early patient identification and therapies to prevent AF ( ClinicalTrials.gov identifier NCT03130985 ).

Subcutaneous implantable cardioverter/defibrillators (S-ICDs) have been developed to offer ICD treatment to patients without venous access to the heart and to overcome complications associated with transvenous leads, particularly lead fracture/insulation defects and endocarditis. Several studies and registries have demonstrated the feasibility and safety of S‑ICD in different groups of patients. Further developments in S‑ICD technology involve the combination with devices that can provide anti-bradycardia and anti-tachycardia pacing if needed. The extravascular ICD (EV-ICD) is a new system that similarly offers ICD therapy without a transvenous lead but uses a substernal instead of a subcutaneous lead to facilitate detection of ventricular fibrillation and to provide anti-tachycardia and also temporary anti-bradycardia pacing. The first animal but also clinical data on EV-ICDs have been published. This review discusses the current state, potential advantages and limitations, and future research of both S‑ICD and EV-ICD.

Introduction Cryoablation has evolved as a safe alternative to radiofrequency ablation in the treatment of several supraventricular arrhythmias and has potential advantages, yet is limited by the properties of the cryogen used. We investigated a novel ultralow temperature cryoablation (ULTCA) system using nitrogen near its liquid-vapor critical point as a freezing source, achieving temperatures as low as -196 degrees Celsius in a long linear catheter with a continuous energy release. Initial safety, procedural and efficacy outcomes of ULTCA are described in patients undergoing cavotricuspid isthmus (CTI) ablation. Methods and results The Cryocure studies (NCT02355106, NCT02839304) are prospective, single-arm, multi-center, first-in-human clinical studies in 17 patients with atrial flutter (AFL) and 13 patients with atrial fibrillation (AF). A total of 30 patients, mean age 65±8 years old and 67% male, were enrolled and underwent ablation of the CTI. Acute success, defined as the confirmation of stable bidirectional conduction block across the CTI, was achieved in all 30 patients. After 12 months of follow-up, 14 out of 17 AFL patients remained free from any AFL. One (3.3%) procedure-related but not device-related serious adverse event was reported, involving transient inferolateral ST-elevation associated with temporary AV conduction block. Conclusion In this first-in-human clinical study the safety and performance results demonstrate the capabilities of ultralow temperature near-critical nitrogen as an effective energy source for CTI ablation. Ongoing, larger, studies should confirm our findings and evaluate the capabilities to create linear and focal transmural lesions in other arrhythmias. This article is protected by copyright. All rights reserved.

Introduction Current guidelines recommend adequate anticoagulation for at least 3 weeks pre- and 4 weeks post-direct current cardioversion (DCCV) to reduce thrombo-embolic risk in patients with atrial fibrillation (AF) lasting greater than 48 h. No specific recommendations exist for DCCV in patients that have undergone left atrial appendage occlusion (LAAO), many of whom are ineligible for anticoagulation. This study aims to observe the efficacy and safety of DCCV post-LAAO in everyday clinical practice. Methods This prospective multicenter registry included DCCVs in patients post-LAAO. Imaging strategy or anticoagulation treatment around DCCV were analyzed. Complications during 30-day follow-up were registered. DCCVs performed in accordance with current guidelines for the general AF population were compared to DCCVs performed deviating from these guidelines. Results In 93 patients (age 65 ± 17 years, CHA2 DS2 -VASC 3.0 ± 1.3) 284 DCCVs were performed between 2010 and 2018, in 271 sinus rhythm was restored. A wide variety of imaging or anticoagulation strategies around DCCV was observed; in 128 episodes strategies deviated from current guidelines. No thrombo-embolic events were observed after any DCCV during 30-day follow-up. In 34 DCCVs trans-esophageal echocardiography (TOE) was performed before DCCV to exclude cardiac thrombi and/or (re-)verify adequate device positioning. In two patients without post-LAAO imaging before DCCV, a device rotation or embolization was observed during scheduled TOE after LAAO. Conclusion DCCV in AF patients after LAAO is highly effective. No thrombo-embolic events were observed in any patient in this observational cohort, regardless of the periprocedural anticoagulation or imaging strategy. Confirmation of adequate device positioning at least once before DCCV seems recommendable.

Introduction The third‐generation subcutaneous implantable cardioverter‐defibrillator (S‐ICD) (EMBLEM™ A219, Boston Scientific) contains a new diagnostic tool to detect atrial fibrillation (AF) in S‐ICD patients, without the use of an intracardiac lead. This is the first study to evaluate the performance of the S‐ICD AF monitor (AFM). Methods The AFM algorithm analyzes a subcutaneous signal for the presence of AF, similar to the signals collected by implantable and wearable diagnostic devices. The AFM algorithm combines heart rate (HR) scatter analysis with an HR histogram. The algorithm was tested against publicly available electrocardiogram databases (simulated performance). Real‐world performance of the algorithm was evaluated by using the S‐ICD LATITUDE remote monitoring (RM) database. Results The simulated performance of the AFM algorithm resulted in a sensitivity of 95.0%, specificity of 100.0%, and positive predictive value (PPV) of 100.0%. To evaluate the real‐world performance of the AFM, 7744 S‐ICD devices were followed for up to 30 months by RM, whereof 99.5% had the AFM enabled. A total of 387 AF episodes were randomly chosen for adjudication, resulting in a PPV of 67.7%. The main cause of misclassification was atrial and ventricular ectopy. Conclusion The AFM exhibited a very high sensitivity and specificity in a simulated setting, designed to maximize PPV in order to minimize the clinical burden of reviewing falsely detected AF events. The real‐world performance of the AFM, enabled in 99.5% of S‐ICD patients, is a PPV of 67.7%.

The completely subcutaneous implantable cardioverter defibrillator (S-ICD) is rapidly evolving to become a complete alternative for the transvenous ICD (TV-ICD) leaving the heart and vasculature untouched. Newer trials and registries in cohorts that are similar to real-world ICD patient populations confirm the initial data on safety and efficacy. Technical improvements have resulted in reduced inappropriate shock rates, although more data are warranted, and new developments such as substernal lead positioning, communication between the S-ICD and a leadless cardiac pacemaker and remote monitoring options have evolved to overcome the shortcomings of S-ICD therapy. With these continuing developments, it is expected that within the next years the S-ICD will continue to evolve to a treatment option for ventricular arrhythmia as effective as the TV-ICD overcoming the shortcomings of transvenous leads as well as the drawbacks of the initial system, providing effective shock therapy, pacing capabilities, low complication and inappropriate therapy rates, and automated remote monitoring.

Atrial fibrillation (AF) is part of a vicious cycle that includes multiple cardiovascular risk factors and comorbidity which can promote atrial remodelling and AF progression. Most AF-related risk factors—hypertension, diabetes, sleep apnoea, obesity and sedentary lifestyle—are in essence modifiable which may prevent AF development. Treatment of associated cardiovascular conditions may prevent both symptoms and future cardiovascular events. For advanced forms of symptomatic AF refractory to lifestyle management and optimal medication, invasive ablation therapies have become a cornerstone. Although electrical trigger isolation from the pulmonary veins is reasonably effective and safe, more potent energy sources including high output-short duration radiofrequency, ultra-low cryo-energy, and electroporation, as well as more sophisticated arrays, balloons, and lattice-tipped catheter tools, are on their way to eliminate existing pitfalls and simplify the procedure. Electroanatomical navigation and mapping systems are becoming available to provide real-time information on ablation lesion quality and the critical pathways of AF in the individual patient to guide more extensive ablation strategies that may enhance long-term outcome for freedom of advanced AF. Surgical techniques, either stand-alone or concomitant to structural cardiac repair, hybrid, or convergent, with novel less invasive access options are developing and can be helpful in situations unsuitable for catheter ablation.

Introduction: Atrial fibrillation (AF) is associated with an increased risk of stroke. Stroke prevention with oral anticoagulation (OAC) is recommended in AF patients at increased risk of stroke. The left atrial appendage (LAA) is the main source of thrombus formation in AF patients. The WATCHMAN percutaneous LAA closure (LAAC) device may serve as an alternative to OAC overcoming disadvantages including the risk of (major) bleeding. Areas covered: This review will focus on LAAC with the Watchman device for stroke prevention in AF patients. Current status, available literature, clinical safety and efficacy will be summarized. Furthermore, the future perspectives of Watchman will be discussed. Expert opinion: LAAC with Watchman appears a promising, safe, and effective alternative to OAC. Ongoing and future studies to consolidate the position of Watchman should focus on comparative safety and efficacy of different LAAC devices, patient selection, various post-procedural antithrombotic regimens, head-to-head comparisons with NOAC, better understanding of device-related thrombus, and the role of the LAA in the propagation of non-valvular AF. This research may attribute to a paradigm shift in which LAAC no longer serves as a ’last resort’ treatment for AF patients ineligible for OAC but may serve as a second-line or even first-line treatment option for AF patients.

Introduction The VICTORY AF Study was designed to evaluate the risk of the procedure and/or device-related strokes in patients with PersAF on warfarin undergoing ablation with a phased radiofrequency (RF) system. Methods The VICTORY AF trial was a prospective, multicenter, single-arm, investigational study. PersAF patients on vitamin K antagonism without major structural heart disease or history of stroke/transient ischemic attack undergoing phased RF ablation for atrial fibrillation (AF) were included. The primary outcome was the incidence of the procedure and/or device-related stroke within 30 days of the ablation by a board-certified neurologist's assessment. The secondary outcomes were an acute procedural success, 6 months effectiveness (defined as the reduction in AF/atrial flutter episodes lasting ≥10 minutes by 48-hour Holter 6 months postablation) and the number of patients with pulmonary vein (PV) stenosis. Results A total of 129 (108 PersAF, 21 long-standing PersAF) patients were treated (mean age: 60.6 ± 7.7; 79.8% male, 54.3% CHA2Ds2-VASc score ≥ 2). Two nondisabling strokes were reported (1.6%); one before discharge and the second diagnosed at the 30-day visit. Due to slow enrollment, the study was terminated before reaching the 95% one-sided upper confidence boundary for stroke incidence. Acute procedural success was 93.8%, and at 6 months, 72.8% of patients demonstrated ≥90% reduction in AF burden, 78.9% were off all antiarrhythmic drugs. There were no patients with PV stenosis of greater than 70%. Conclusions VICTORY AF demonstrated a 1.6% incidence of stroke in PersAF undergoing ablation with a phased RF system which did not meet statistical confidence due to poor enrollment. The secondary outcomes suggest comparable efficacy to phased RF in the tailored treatment of permanent AF trial. Rigorous clinical evaluation of the stroke risk of new AF ablation technologies as well as restriction to Vitamin K antagonist anticoagulation appears to be unachievable goals in a clinical multicenter IDE trial of AF ablation in the current era.

Excluding the left atrial appendage in patients with nonvalvular atrial fibrillation is a mechanical way to decrease stroke risk. During endothelialization, the closure device is exposed to circulating blood, which might activate the coagulation cascade. In excessive proportions, possibly resulting in the development of device-related thrombus, requiring a bridging period with optimal antithrombotic treatment. Initial protocol treatment is less suitable for patients with contraindications to anticoagulation. Less intensive antithrombotic regimens investigated suggest safety and efficacy, however further research is required. A tailored treatment, considering bleeding and thromboembolic risk based on patient/procedural characteristics in every patient, is probably the best approach.

Aims The GOLD AF Registry has been designed to prospectively assess the population, indications, and outcomes using second-generation phased radiofrequency (RF) ablation (pulmonary vein ablation catheter GOLD) in a global examination of standard-of-care use for the treatment of paroxysmal and persistent atrial fibrillation (AF). Methods and results GOLD AF (NCT02433613) is a prospective, observational, multi-centre registry designed to characterize efficacy and safety of phased RF ablation in patients with AF. The primary endpoint was freedom from AF recurrence at 12-month follow-up after a 90-day blanking period. Ancillary objectives include safety, procedural efficiency, and quality of life (QoL). The QoL assessment using the Atrial Fibrillation Effect on QualiTy-of-Life (AFEQT) and the European Heart Rhythm Association (EHRA) Score of AF-related symptoms was collected at baseline and 12 months. In total, 1054 patients were included in this analysis (age 60.6, 67.6% male, 26.5% PersAF). Kaplan–Meier estimate of freedom from AF recurrence was 77.7% at 12 months. Peri-procedural device or procedure-related complications were observed in 26 (2.5%) patients, with a low stroke rate of 0.3%. One-year post-ablation, the EHRA AF Symptom score decreased in 68% of patients. The AFEQT score improvement was observed in 88.4% and 90.4% of patients who completed the questionnaire in-person or interviewed by phone at 12 month follow-up, respectively. Conclusion Phased RF ablation for the treatment of paroxysmal and persistent AF demonstrated a 77.7% freedom from AF recurrence at 12 months in addition to a significant reduction in arrhythmia symptoms and clinically meaningful improved QoL. Low peri-procedural complication rate of

Atrial septal defect, persistent foramen ovale and the left atrial appendage are nowadays often percutaneously closed with implantable devices. These interventions may be complicated by thromboembolic events and the perfect post-procedural antithrombotic management is still under investigation. The mechanisms leading to left atrial device-related thrombus and thromboembolic complications are not fully understood. Biomarkers of coagulation activation are elevated following percutaneous device placement, peaking within one month and returning to baseline values after three months. By contrast, platelet reactivity shows no post-procedural increase. This suggests that an optimal antithrombotic regimen should perhaps include (oral) anticoagulation therapy rather than the currently more frequently prescribed antiplatelet-based regimen. Furthermore, biomarkers of endothelial activation, fibrinolysis, and on-treatment platelet reactivity may be of value in predicting device-related thrombus and bleeding and guide future medical strategy, facilitating personalized medicine.

Introduction: The extravascular ICD (EV ICD) system with substernal lead placement is a novel non-transvenous alternative to current commercially available ICD systems. The EV ICD provides defibrillation and pacing therapies without the potential long-term complications of endovascular lead placement. Methods: This paper summarizes the development of the EV ICD, including the pre-clinical and clinical evaluations that have contributed to system and procedural refinements to date. Results: Extensive pre-clinical research evaluations and 4 human clinical studies with >140 combined acute and chronic implants have enabled the development and refinement of the EV ICD system, currently in worldwide pivotal study. Conclusion: The EV ICD may represent a clinically valuable solution in protecting patients from sudden cardiac death while avoiding the long-term consequences of transvenous hardware. The EV ICD offers advantages over transvenous and subcutaneous systems by avoiding placement in the heart and vasculature; relative to subcutaneous systems, EV ICD requires less energy for defibrillation, enabling a smaller device, and provides pacing features such as anti-tachycardia and asystole pacing in a single system.

Background Rhythm control has become an essential part of adequate management in atrial fibrillation (AF) to reduce symptoms and ultimately to improve health related quality of life (HRQoL). Totally thoracoscopic ablation has been established over the last years as an effective and safe rhythm control strategy, especially for persistent AF, but quality of life data are lacking. Purpose To assess the impact of totally thoracoscopic ablation on HRQoL in patients with symptomatic AF. Methods Consecutive patients with symptomatic AF undergoing totally thoracoscopic ablation at a referral centre in the Netherlands (July 2016 – October 2019) were included. The primary outcome was quality of life. Short Form 36 and Atrial Fibrillation Effect on Quality-of-Life (AFEQT) health surveys were collected at baseline, 1, 3, 6 and 12 months. Clinical improvement was measured as the relative increase of the QoL-score at 1 year compared to the baseline score (in %). Multilevel regression modelling was used, coupled with fractional polynomials for adjustment of age differences and nonlinear time trends, to investigate the one-year clinical trajectories of sex differences in QoL subscales. Secondary outcomes included rhythm success (freedom from any recurrence of atrial tachyarrhythmia>30 sec), mortality and stroke. Results 191 patients were included (63.9±8.6 years, 68% male, 22.5% paroxysmal AF, 69.6% persistent AF and 7.9% long-term persistent AF, 66.5% having at least one previous failed catheter ablation, with median Cha2ds2 Vasc score of 2 [IQR 1–3]). AFEQT sum scores (52.6 points at baseline) substantially improved after three months (49.8%; p Conclusions This study reveals significant improvement of HRQoL three months after thoracoscopic ablation that persisted up to 1-year, also when adjusted for sex and age differences. Despite AF recurrence or adverse events AF related QoL still improved. Trials are necessary to confirm these data. Funding Acknowledgement Type of funding sources: None.

Background: Transvenous implantable cardiac defibrillators (TV ICD) provide life-saving therapy for millions of patients worldwide. However, they are susceptible to several potential short- and long- term complications including cardiac perforation and pneumothorax, lead dislodgement, venous obstruction, and infection. The extravascular ICD (EV ICD) system’s novel design and substernal implant approach avoids the risks associated with TV ICDs while still providing pacing features and similar generator size to TV ICDs. Study Design: The EV ICD pivotal study is a prospective, multi-center, single-arm, non-randomized, pre-market clinical study designed to examine the safety and acute efficacy of the system. This study will enroll up to 400 patients with a Class I or IIa indication for implantation of an ICD. Implanted subjects will be followed up to approximately 3.5 years, depending on when the patient is enrolled. Objective: The clinical trial is designed to demonstrate safety and effectiveness of the EV ICD system in human use. The safety endpoint is freedom from major complications, while the efficacy endpoint is defibrillation success. Both endpoints will be assessed against prespecified criteria. Additionally, this study will evaluate antitachycardia pacing (ATP) performance, electrical performance, extracardiac pacing sensation, asystole pacing, appropriate and inappropriate shocks, as well as a summary of adverse events. Conclusion: The EV ICD pivotal study is designed to provide clear evidence addressing the safety and efficacy performance of the EV ICD System.

Introduction In patients with a prior myocardial infarction (MI) but preserved left ventricular (LV) function, sustained ventricular arrhythmias (VAs) may arise in the setting of an acute coronary syndrome (ACS). It is unknown whether an implantable cardioverter-defibrillator (ICD) is mandatory in these patients as VA might be triggered by a reversible cause. The purpose of this study is to analyze the benefit of ICD therapy in this patient population. Methods We conducted a retrospective observational study in ICD recipients implanted from 2008 to 2011. The study group consisted of patients with sustained VA in the setting of an ACS, with a history of MI, but with left ventricular ejection fraction (LVEF) greater than 35 (group A). The two control groups consisted of patients admitted with VA with a history of MI, but without ACS at presentation, either with LVEF greater than 35% (group B) or ≤35% (group C). The primary endpoint was the number of patients with appropriate ICD therapy (antitachycardia pacing or shock). Results A total of 291 patients were included with a mean follow-up of 5.3 years. Appropriate ICD therapy occurred in 45.6% of the patients in group A vs 51.6% and 60.4% in groups B and C (P = .11). In group A, 31.1% received an appropriate ICD shock vs 34.7% and 44.3% in control groups B and C (P = .12). Conclusion On the basis of these data, ICD implantation seems warranted in patients with history of MI presenting with VA in the setting of an ACS, despite preserved LV function and adequate revascularization. Further trials, preferably randomizes, should be performed to address these findings.

Resumen Introduccion y objetivos Los pacientes ancianos con fibrilacion auricular estan en mayor riesgo de eventos cardioembolicos y hemorragia mayor que los mas jovenes. El cierre de la orejuela izquierda (COI) podria ser una opcion atractiva para estos pacientes, pero hay pocos datos sobre los resultados del COI de pacientes de 85 o mas anos. El objetivo del presente estudio es evaluar la seguridad y la eficacia del COI de pacientes de 85 o mas anos. Metodos Se analizo a 1.025 pacientes incluidos en el registro EWOLUTION que se habian sometido al COI, se identifico a 84 de edad ≥ 85 anos y se los comparo con el grupo de menos edad. Resultados Los pacientes de 85 o mas anos tenian mayores riesgos estimados de accidente cerebrovascular y de hemorragias que los pacientes mas jovenes (edad ≥ 85 frente a Conclusiones El COI de los pacientes de edad ≥ 85 anos es seguro y eficaz a pesar del alto riesgo de eventos embolicos y hemorragicos de estos pacientes. El COI puede ser una alternativa razonable a la anticoagulacion oral para estos pacientes.

Aims Cardiac resynchronization therapy (CRT) upgrades may be less likely to improve following intervention. Leadless left ventricular (LV) endocardial pacing has been used for patients with previously failed CRT or high-risk upgrades. We compared procedural and long-term outcomes in patients undergoing coronary sinus (CS) CRT upgrades with high-risk and previously failed CRT upgrades undergoing LV endocardial upgrades. Method and results Prospective consecutive CS upgrades between 2015 and 2019 were compared with those undergoing WiSE-CRT implantation. Cardiac resynchronization therapy response at 6 months was defined as improvement in clinical composite score (CCS) and a reduction in LV end-systolic volume (LVESV) ≥15%. A total of 225 patients were analysed; 121 CS and 104 endocardial upgrades. Patients receiving WiSE-CRT tended to have more comorbidities and were more likely to have previous cardiac surgery (30.9% vs. 16.5%; P = 0.012), hypertension (59.2% vs. 34.7%; P, Graphical Abstract

Aims This study was performed to develop and externally validate prediction models for appropriate implantable cardioverter-defibrillator (ICD) shock and mortality to identify subgroups with insufficient benefit from ICD implantation. Methods and results We recruited patients scheduled for primary prevention ICD implantation and reduced left ventricular function. Bootstrapping-based Cox proportional hazards and Fine and Gray competing risk models with likely candidate predictors were developed for all-cause mortality and appropriate ICD shock, respectively. Between 2014 and 2018, we included 1441 consecutive patients in the development and 1450 patients in the validation cohort. During a median follow-up of 2.4 (IQR 2.1–2.8) years, 109 (7.6%) patients received appropriate ICD shock and 193 (13.4%) died in the development cohort. During a median follow-up of 2.7 (IQR 2.0–3.4) years, 105 (7.2%) received appropriate ICD shock and 223 (15.4%) died in the validation cohort. Selected predictors of appropriate ICD shock were gender, NSVT, ACE/ARB use, atrial fibrillation history, Aldosterone-antagonist use, Digoxin use, eGFR, (N)OAC use, and peripheral vascular disease. Selected predictors of all-cause mortality were age, diuretic use, sodium, NT-pro-BNP, and ACE/ARB use. C-statistic was 0.61 and 0.60 at respectively internal and external validation for appropriate ICD shock and 0.74 at both internal and external validation for mortality. Conclusion Although this cohort study was specifically designed to develop prediction models, risk stratification still remains challenging and no large group with insufficient benefit of ICD implantation was found. However, the prediction models have some clinical utility as we present several scenarios where ICD implantation might be postponed.

Background One third of primary prevention implantable cardioverter‐defibrillator patients receive appropriate therapy, but all remain at risk of defibrillator complications. Information on these complications in contemporary cohorts is limited. This study assessed complications and their risk factors after defibrillator implantation in a Dutch nationwide prospective registry cohort and forecasts the potential reduction in complications under distinct scenarios of updated indication criteria. Methods and Results Complications in a prospective multicenter registry cohort of 1442 primary implantable cardioverter‐defibrillator implant patients were classified as major or minor. The potential for reducing complications was derived from a newly developed prediction model of appropriate therapy to identify patients with a low probability of benefitting from the implantable cardioverter‐defibrillator. During a follow‐up of 2.2 years (interquartile range, 2.0–2.6 years), 228 complications occurred in 195 patients (13.6%), with 113 patients (7.8%) experiencing at least one major complication. Most common ones were lead related (n=93) and infection (n=18). Minor complications occurred in 6.8% of patients, with lead‐related (n=47) and pocket‐related (n=40) complications as the most prevailing ones. A surgical reintervention or additional hospitalization was required in 53% or 61% of complications, respectively. Complications were strongly associated with device type. Application of stricter implant indication results in a comparable proportional reduction of (major) complications. Conclusions One in 13 patients experiences at least one major implantable cardioverter‐defibrillator–related complication, and many patients undergo a surgical reintervention. Complications are related to defibrillator implantations, and these should be discussed with the patient. Stricter implant indication criteria and careful selection of device type implanted may have significant clinical and financial benefits.

Aims Pulmonary vein isolation (PVI) for atrial fibrillation (AF) has become increasingly safe and effective with the evolution of single-tip ablation catheters aided by contact force sensing (ST-CF) and single-shot devices such as the second-generation pulmonary vein ablation catheter (PVAC) Gold multi-electrode array. The multicentre randomized GOLD FORCE trial was conducted to evaluate non-inferiority of safety and efficacy of PVAC Gold PVI compared to ST-CF ablation for paroxysmal AF. Methods and results The primary efficacy endpoint documented AF recurrence ≥30 s was assessed by time-to-first-event analysis after a 90-day blanking period using repeated 7-day Holters. Secondary endpoints include acute success and procedural characteristics. Safety endpoints included procedural complications, stroke/transient ischaemic attack (TIA), tamponade, bleeding, and access site complications. Two hundred and eight patients underwent randomization and PVI (103 assigned to PVAC Gold, 105 to ST-CF). Acute success rates were 95% and 97% for PVAC Gold and ST-CF, respectively. At 12 months, AF recurrence was observed in 46.6% of the PVAC Gold group and in 26.2% of the ST-CF group [absolute efficacy difference 20.4% (95% confidence interval, CI 7.5–33.2%), hazard ratio 2.05 (95% CI 1.28–3.29), P = 0.003]. PVAC Gold had significantly shorter procedure and ablation times. Complication rates were 5.7% and 4.9% for PVAC Gold and ST-CF, respectively (P = 0.782). Conclusion In this multicentre randomized clinical trial, ablation with ST-CF and PVAC Gold ablation catheters non-inferiority for efficacy was not met. AF recurrence was significantly more frequent in the PVAC Gold group compared to single-tip contact force group. Both groups had similarly low rates of adverse events. PVAC Gold ablation had significantly shorter procedure and ablation times.

BACKGROUND In this analysis of the EWOLUTION registry, we evaluated the incidence, relevance and predictors of device-related thrombus in a large multi-center real-world cohort undergoing LAAc with the WATCHMAN device. METHODS AND RESULTS We analyzed the 835 patients who underwent percutaneous LAA closure with the WATCHMAN device in the EWOLUTION registry in whom at least one TEE follow up was performed. Patients were 74 ± 9 y/o and were at high risk for stroke and bleeding (CHA2DS2-VASC-Score 4.3 ± 1.7; HAS-BLED-Score 2.3 ± 1.2). Device-related thrombus was detected in 4.1% (34/835) after a median of 54 days (IQR 42-111 days) with 91.2% (31/34) being detected within 3 months after the procedure or at the time of first TEE. Hereby DRT occurred irrespective of postprocedural anticoagulation. Patients with DRT more frequently had long-standing, non-paroxysmal atrial fibrillation (82.4 vs. 64.9%, p

Introduction Postoperative atrial fibrillation (POAF) occurs in up to 45% of patients following cardiothoracic surgery and is defined as any atrial tachyarrhythmia occurring ≤30 days after surgery. Consequently, atrial arrhythmias after 30 days are regarded as new-onset AF. However, biological and clinical data on the association between POAF and new-onset AF, or empirical data supporting the cut-off of 30 days, are lacking. Purpose We hypothesize that patients with POAF are biologically different with respect to atrial fibrosis compared to patients who develop new-onset AF. Methods PREDICT AF is a prospective, multicenter, observational trial that included patients with a CHA2DS2VAsc score≥2 without a history of AF. Patients underwent CABG or valve surgery and the left atrial appendage (LAA) was removed during surgery. The LAA was obtained for expression analysis of extracellular matrix (ECM) genes such as collagen 1 (COL1A1), collagen 3 (COL3A1) and fibronectin (FN1) by qPCR. Patients were monitored during hospitalisation and followed-up at 1, 6, 12 and 24 months with 24-h Holters and ECGs. The primary endpoint was any recorded atrial tachyarrhythmia lasting >30 seconds. We documented all new-onset arrhythmias over time in order to determine potential cut-offs for POAF (Figure A). We then compared the effects of using a 30-, 50- or 70-day cut-off on the rate of new-onset AF and the differences in expression of fibrosis related genes. Results PREDICT AF included 150 cardiac surgery patients: 115 CABG, 11 valve surgeries and 24 combined surgeries. Participants had a median follow-up of 1.9 years [1.0–2.0], were 68±7 years old and 19 (13%) were female. POAF 30 days developed in 21 (14%) patients. Of the 21 patients with new-onset AF, 20 (95%) also had had POAF. New-onset AF defined by a cut-off of 50 days, developed in 15 (10%) patients. In total, 9 patients had an episode of AF between 30 and 50 days, of whom 6 (66.6%) had no AF episodes thereafter. Most of these patients under–went (concomitant) aortic valve surgery. The gene expression of ECM components was significantly more predictive of new-onset AF when using a cut-off of 50 days or even 70 days than when using a cut-off of 30 days (Figure B). Conclusion With stringent monitoring we detected 42% POAF New-onset AF prediction with ECM genes Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): NWO VIDI

Background Evidence regarding post-procedural antithrombotic regimes other than used in randomized trials assessing percutaneous left atrial appendage (LAA) closure is limited. Purpose The present work aimed to compare different antithrombotic strategies applied in the real-world EWOLUTION study. Methods A total of 998 patients with successful WATCHMAN implantation at 47 centers were available for the present analysis. The composite ischemic endpoint of stroke, TIA, systemic embolism and device thrombus as well as the bleeding endpoint defined as at least major bleeding according to BARC were assessed during an initial period (from implant until first medication change) and long-term period (from first change until up to 2 years). Results The antithrombotic medication chosen in the initial phase was dual antiplatelet therapy (DAPT) in 60%, oral anticoagulation (OAC) in 27%, single antiplatelet therapy (SAPT) in 7% and no medication in 6%. In the long-term phase SAPT was used in 65%, DAPT in 23%, no therapy in 8% and OAC in 4%. No significant differences were found between the groups regarding the ischemic endpoint both in the initial period (Kaplan-Meier estimated rate 2.9% for DAPT vs. 4.3% for OAC vs. 3.9% for SAPT or no therapy; p=0.97) and in the second period (4.2% for SAPT vs. 1.8% for DAPT vs. 3.5% for no therapy; p=0.36). With respect to bleeding events the only difference was found in the initial phase with a higher incidence in patients under SAPT or no therapy (1.0% for DAPT vs. 0.8% for OAC vs. 7.4% for SAPT or no therapy; p=0.01). No differences in bleeding complications were observed during the second period (2.6% for SAPT vs. 2.9% for DAPT vs. 2.2% for no therapy; p=0.88). Conclusions Tailored antithrombotic treatment using even very reduced strategies such as SAPT or no therapy showed no significant differences regarding ischemic complications after LAA closure. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Boston Scientific

Background: Recent data demonstrate promising effects on left ventricular dysfunction and left ventricular ejection fraction (LVEF) improvement following ablation for atrial fibrillation (AF) in patients with heart failure. We sought to study the relationship between LVEF, New York Heart Association class on presentation, and the end points of mortality and heart failure admissions in the CASTLE-AF study (Catheter Ablation for Atrial Fibrillation With Heart Failure) population. Furthermore, predictors for LVEF improvement were examined. Methods: The CASTLE-AF patients with coexisting heart failure and AF (n=363) were randomized in a multicenter prospective controlled fashion to ablation (n=179) versus pharmacological therapy (n=184). Left ventricular function and New York Heart Association class were assessed at baseline (after randomization) and at each follow-up visit. Results: In the ablation arm, a significantly higher number of patients experienced an improvement in their LVEF to >35% at the end of the study (odds ratio, 2.17; P P =0.006), all-cause mortality (HR, 0.54; P =0.019), and cardiovascular hospitalizations (HR, 0.66; P =0.017). In the ablation group, New York Heart Association I/II patients at the time of treatment had the strongest improvement in clinical outcomes (primary end point: HR, 0.43; P P =0.001). Conclusions: Compared with pharmacological treatment, AF ablation was associated with a significant improvement in LVEF, independent from the severity of left ventricular dysfunction. AF ablation should be performed at early stages of the patient’s heart failure symptoms.

Background: Endocardial pacing may be beneficial in patients who fail to improve following conventional epicardial cardiac resynchronization therapy (CRT). The potential to pace anywhere inside the left ventricle thus avoiding myocardial scar and targeting the latest activating segments may be particularly important. The WiSE-CRT system (EBR systems, Sunnyvale, CA) reliably produces wireless, endocardial left ventricular (LV) pacing. The purpose of this analysis was to determine whether this system improved symptoms or led to LV remodeling in patients who were nonresponders to conventional CRT. Method: An international, multicenter registry of patients who were nonresponders to conventional CRT and underwent implantation with the WiSE-CRT system was collected. Results: Twenty-two patients were included; 20 patients underwent successful implantation with confirmation of endocardial biventricular pacing and in 2 patients, there was a failure of electrode capture. Eighteen patients proceeded to 6-month follow-up; endocardial pacing resulted in a significant reduction in QRS duration compared with intrinsic QRS duration (26.6 ± 24.4 ms; P =.002) and improvement in left ventricular ejection fraction (LVEF) (4.7 ± 7.9%; P =.021). The mean reduction in left ventricular end-diastolic volume was 8.3 ± 42.3 cm3 (P =.458) and left ventricular end-systolic volume (LVESV) was 13.1 ± 44.3 cm3 (P =.271), which were statistically nonsignificant. Overall, 55.6% of patients had improvement in their clinical composite score and 66.7% had a reduction in LVESV ≥15% and/or absolute improvement in LVEF ≥5%. Conclusion: Nonresponders to conventional CRT have few remaining treatment options. We have shown in this high-risk patient group that the WiSE-CRT system results in improvement in their clinical composite scores and leads to LV remodeling.

International audience; BACKGROUND Biventricular endocardial pacing (BiV ENDO) is a therapy for heart failure patients who cannot receive transvenous epicardial cardiac resynchronization therapy (CRT) or have not responded adequately to CRT. BiV ENDO CRT can be delivered by a new wireless LV ENDO pacing system (WiSE-CRT system; EBR Systems, Sunnyvale, CA), without the requirement for lifelong anticoagulation.OBJECTIVE The purpose of this study was to assess the safety and efficacy of the WiSE-CRT system during real-world clinical use in an international registry.METHODS Data were prospectively collected from 14 centers implanting the WiSE-CRT system as part of the WiCS-LV Post Market Surveillance Registry. (ClinicalTrials.gov Identifier: NCT02610673).RESULTS Ninety patients from 14 European centers underwent implantation with the WiSE-CRT system. Patients were predominantly male, age 68.2 +/- 10.5 years, left ventricular ejection fraction 30.6% +/- 8.9%, mean QRS duration 180.7 +/- 27.0 ms, and 40% with ischemic etiology. Successful implantation and delivery of BiV ENDO pacing was achieved in 94.4% of patients. Acute (

Objectives The ASD2 (Acute Extravascular Defibrillation, Pacing, and Electrogram) study evaluated the ability to adequately sense, pace, and defibrillate patients with a novel implantable cardioverter-defibrillator (ICD) lead implanted in the substernal space. Background Subcutaneous ICDs are an alternative to a transvenous defibrillator system when transvenous implantation is not possible or desired. An alternative extravascular system placing a lead under the sternum has the potential to reduce defibrillation energy and the ability to deliver pacing therapies. Methods An investigational lead was inserted into the substernal space via a minimally invasive subxiphoid access, and a cutaneous defibrillation patch or subcutaneous active can emulator was placed on the left mid-axillary line. Pacing thresholds and extracardiac stimulation were evaluated. Up to 2 episodes of ventricular fibrillation were induced to test defibrillation efficacy. Results The substernal lead was implanted in 79 patients, with a median implantation time of 12.0 ± 9.0 min. Ventricular pacing was successful in at least 1 vector in 76 of 78 patients (97.4%), and 72 of 78 (92.3%) patients had capture in ≥1 vector with no extracardiac stimulation. A 30-J shock successfully terminated 104 of 128 episodes (81.3%) of ventricular fibrillation in 69 patients. There were 7 adverse events in 6 patients causally (n = 5) or possibly (n = 2) related to the ASD2 procedure. Conclusions The ASD2 study demonstrated the ability to pace, sense, and defibrillate using a lead designed specifically for the substernal space.

Introduction: Treatment infections is challenging in pacemaker (PM) dependent patients. We proposed a novel implantation strategy for this group of patients. Methods: Patients who were PM dependent and were admitted with a PM infection received a combined procedure of left ventricular (LV) epicardial implantation of a PM lead and subsequent extraction of the infected system. No temporary pacing wire was used and the PM generator was placed in the left flank. Results: Between 2012 and 2015 we treated 16 patients who were PM dependent and with a PM infection. The majority of patients were male (81% [13/16]) and the median age was 71 years (50–91). The cause of infection was valvular endocarditis in 38% (6/16), lead infection in 25% (4/16), and isolated pocket infection in 38% (6/16). All patients underwent epicardial implantation of a LV lead (1084T bipolar lead; St. Jude Medical Myodex, St. Paul, MN, USA) and extraction of the infected device. There was no occurrence of periprocedural mortality and no postprocedural tamponades. There was one complication in the form of a hemorrhage at the infected device extraction site. In the median follow-up period of 17 months there were four of 16 deaths, none of which were attributable to epicardial LV implantation. LV-lead threshold was 1.1V (±0.7V) upon implantation that increased to 1.2V (±0.6V) at 0.4-ms pulse duration. There were no reinfections of the epicardial lead or device. Conclusion: Epicardial left ventricle PM implantation and subsequent extraction of an infected PM in PM-dependent patients is feasible and safe with good long-term outcome.

Introduction Pericardial effusion/tamponade (PE/PT) is a rare but serious complication following left atrial appendage closure (LAAC). It may be speculated that LAA contraction during sinus rhythm (SR) exerts mechanical force on the device that eventually leads to PE. We sought to determine the incidence and predictors of PE following LAAC using Watchman with special emphasis on the underlying heart rhythm during implant. Methods and results From 47 centers in 13 European countries 1,020 patients underwent LAAC and data on baseline rhythm were available from 1,010 patients (mean age 73 ± 9 years, 60% male, median CHA2DS2-VASc = 4). Data were collected via electronic case report forms. A Cox proportional hazard model was calculated adjusting for multiple variables: age, gender, number of recaptures, and device oversizing. During implant, 41% and 59% of patients were in SR and atrial fibrillation (AF), respectively. PE/PT rate was significantly lower in patients implanted during AF at day 30 postimplant (n = 1; 0.2% vs. n = 6; 1.5%; P = 0.02). No PE requiring intervention occurred in the AF group compared to 5 events (1.2%) in the SR group (P = 0.01). While univariate analysis identified SR and gender as predictors for PE/tamponade, multivariate analysis only showed a statistical trend for both variables. Conclusion The overall incidence of PE/PT was very low after LAAC using Watchman. Although SR was not identified as an independent predictor of PE/PT, all events requiring intervention occurred in patients with SR. It may be advisable to perform an extended echocardiographic follow-up in that patient population.

Background Mortality and morbidity are higher among patients with atrial fibrillation and heart failure than among those with heart failure alone. Catheter ablation for atrial fibrillation has been proposed as a means of improving outcomes among patients with heart failure who are otherwise receiving appropriate treatment. Methods We randomly assigned patients with symptomatic paroxysmal or persistent atrial fibrillation who did not have a response to antiarrhythmic drugs, had unacceptable side effects, or were unwilling to take these drugs to undergo either catheter ablation (179 patients) or medical therapy (rate or rhythm control) (184 patients) for atrial fibrillation in addition to guidelines-based therapy for heart failure. All the patients had New York Heart Association class II, III, or IV heart failure, a left ventricular ejection fraction of 35% or less, and an implanted defibrillator. The primary end point was a composite of death from any cause or hospitalization for worsening heart f...

Aims Long-term results from catheter ablation therapy for atrial fibrillation (AF) remain uncertain and clinical practice guidelines recommend continuation of long-term oral anticoagulation in patients with a high stroke risk. Left atrial appendage closure (LAAC) with Watchman has emerged as an alternative to long-term anticoagulation for patients accepting of the procedural risks. We report on the initial results of combining catheter ablation procedures for AF and LAAC in a multicentre registry. Methods and results Data were pooled from two prospective, real-world Watchman LAAC registries running in parallel in Europe/Middle-East/Russia (EWOLUTION) and Asia/Australia (WASP) between 2013 and 2015. Of the 1140 patients, 139 subjects at 10 centres underwent a concomitant AF ablation and LAAC procedure. The mean CHA2DS2-VASc score was 3.4 ± 1.4 and HAS-BLED score 1.5 ± 0.9. Successful Watchman implantation was achieved in 100% of patients. The overall 30-day serious adverse event (SAE) rate was 8.7%, with the device and/or procedure-related SAE rate of 1.4%. One pericardial effusion required percutaneous drainage, but there were no strokes, device embolization, or deaths at 30 days. The 30-day bleeding SAE rate was 2.9% with 55% of patients prescribed NOAC and 38% taking warfarin post-procedure. Conclusion The outcomes from these international, multicentre registries support the feasibility and safety of performing combined procedures of ablation and Watchman LAAC for patients with non-valvular AF and high stroke risk. Further data are needed on long-term outcomes for the hybrid technique on all-cause stroke and mortality.

Aims Long-term freedom from atrial fibrillation (AF) after catheter ablation (CA) and consequently the potential for stroke reduction remain unpredictable. Percutaneous left atrial appendage closure (LAAC) is an effective mechanical alternative to oral anticoagulation (OAC) for stroke prevention in AF patients. This study aims to evaluate long-term clinical results of combined CA and LAAC in one single procedure. Methods and results Patients with non-valvular AF who underwent combined CA and LAAC procedure were included in the retrospective compilation of independent prospective general LAAC registries at the individual centres. Transoesophageal echocardiography (TOE) was used to evaluate device position and LAA sealing. Between 2009 and 2015, 349 patients with AF (58% male, age 63.1 ± 8.2 years; score for stroke prediction in AF patients (CHA2DS2-VASc) 3.0; score for major bleeding in patients on anticoagulation (HAS-BLED) 3.0; 56% paroxysmal AF) were included. Indications for LAAC included previous stroke (38%), history of bleeding (22%), and physician/patient preference (29%). Periprocedural complications up to 30 days included pericardial effusion (1.5%) and one minor stroke (0.3%) but no death. After 6 weeks, TOE showed successful sealing of the LAA in 98.9%. After 35 months of follow-up, 51% of patients had AF recurrence. A total of nine ischaemic strokes were recorded, resulting in an annualized stroke rate of 0.9% compared to an expected stroke rate of 3.2% without anticoagulation and combined treatment. Conclusion This large pooled multicentre analysis of five prospective registries shows that combining CA and LAAC is feasible, safe, and successful. Long-term follow-up shows greatly reduced stroke and bleeding rates despite recurrence of AF in more than half of the patients.

Introduction Structural heart interventions are guided by transoesophageal or intracardiac echocardiography (TEE/ICE). MicroTEE, developed for paediatric purposes, is smaller and therefore less invasive and traumatic, avoiding the need for general anaesthesia. We aimed to show feasibility of procedural guidance by comparing image quality of microTEE with standard TEE and ICE during adult transcatheter interventions, and assess the accuracy in obtaining left atrial appendage (LAA) measurements between the microTEE probe and standard TEE. Methods and results We prospectively included 49 patients (20 women, 64 ± 18 years). Intraprocedural images were obtained by using the microTEE probe and standard (2D and 3D) TEE (LAA closure, MitraClip implantation) or ICE (interatrial communication closure, transseptal puncture for left atrial ablation). Two echocardiographers independently assessed image quality from 1 (excellent) to 4 (poor) and performed LAA measurements. Use of microTEE was not related to significant discomfort. Image quality obtained with the microTEE probe was lower than with standard TEE (2 [1–2] vs. 1 [1–2]; p = 0.04) and comparable with ICE images (2 [1–2] vs. 2 [1–2], p = 0.13). MicroTEE showed a wider field of view than ICE. LAA measurements on images obtained by microTEE were strongly associated with standard TEE. Conclusions MicroTEE seems feasible for guidance during transcatheter heart interventions in adults. MicroTEE imaging offers a wider field of view than ICE, and its accuracy is comparable with TEE. In transcatheter interventions performed under conscious sedation, microTEE might be a viable and advantageous alternative to standard TEE or ICE.

Background Left atrial appendage (LAA) occlusion with WATCHMAN has emerged as viable alternative to vitamin K antagonists in randomized controlled trials. Objective EWOLUTION was designed to provide data in routine practice from a prospective multicenter registry. Methods A total of 1025 patients scheduled for a WATCHMAN implant were prospectively and sequentially enrolled at 47 centers. Indication for LAA closure was based on European Society of Cardiology guidelines. Follow-up and transesophageal echocardiography (TEE) were performed per local practice. Results The baseline CHA2DS2-VASc score was 4.5 ± 1.6; the mean age was 73.4 ± 9 years; previous transient ischemic attack/ischemic stroke was present in 312 (30.5%), 155 (15.1%) had previous hemorrhagic stroke, and 320 (31.3%) had a history of major bleeding; and 750 (73%) were deemed unsuitable for oral anticoagulation therapy. WATCHMAN implant succeeded in 1005 (98.5%) of patients, without leaks >5 mm in 1002 (99.7%) with at least 1 TEE follow-up in 875 patients (87%). Antiplatelet therapy was used in 784 (83%), while vitamin K antagonists were used in only 75 (8%). At 1 year, mortality was 98 (9.8%), reflecting the advanced age and comorbidities in this population. Device thrombus was observed in 28 patients at routine TEE (3.7%) and was not correlated with the drug regimen (P = .14). Ischemic stroke rate was 1.1% (relative risk 84% vs estimated historical data); the major bleeding rate was 2.6% and was predominantly (2.3%) nonprocedure/device related. Conclusion LAA closure with the WATCHMAN device has a high implant and sealing success. This method of stroke risk reduction appears to be safe and effective with an ischemic stroke rate as low as 1.1%, even though 73% of patients had a contraindication to and were not using oral anticoagulation.

Aims While LAA closure has recently been incorporated into both European and US guidelines for stroke prevention, uncertainties regarding post-procedural drug therapy so far limit its adoption. The aim of this analysis is to compare real-world outcome data stratified for the post-procedural drug regimen employed. Methods and results One thousand and five patients were implanted with a WATCHMAN device in the prospective EWOLUTION study at 47 centres; 73.5% of the patients were deemed contraindicated for long-term OAC therapy. Here we report on three-month data including the first follow-up TOE exam for 94% of the study population. Following LAA closure, patients received DAPT, VKA, NOAC, single antiplatelet or no therapy (60.3%, 15.4%, 10.9%, 7% and 6.5%, respectively). Device thrombus (2.6%), stroke (0.4%) and major bleeding SAE (2.6%) rates were low overall and did not vary by post-implantation medication strategy. Patients on NOAC had the lowest bleeding rate, without an increase in device thrombus or stroke rates. Conclusions LAA closure with the WATCHMAN device is feasible in patients with a relative or absolute contraindication to oral anticoagulation. Neither DAPT nor NOAC therapy leads to a significant increase in device thrombus, stroke or bleeding compared to the standard VKA regimen. Numerically, NOAC therapy had the lowest event rate.

Objectives This study assessed the defibrillation efficacy of the substernal-lateral electrode configuration. Background Subcutaneous implantable cardioverter-defibrillators (ICDs) are regarded as alternatives to transvenous ICDs in certain subjects. However, substantially higher shock energy of up to 80 J may be required. Proposed is a new defibrillation method of placing the shock coil into the substernal space. Methods This prospective, nonrandomized, feasibility study was conducted in subjects scheduled for midline sternotomy or implant of ICD. A blunted end tunneling tool was used to insert a defibrillation lead behind the sternum using a percutaneous subxiphoid approach. A skin patch electrode was placed on the left mid-axillary line at the fourth to fifth intercostal space. After ventricular fibrillation induction, a single 35-J shock was delivered between the lead and skin patch. Results Sixteen subjects (12 males, 4 females; mean age: 61.6 ± 11.8 years) were enrolled. The mean lead placement time was 11.1 ± 6.6 min. Of the 14 subjects with successfully induced ventricular fibrillation episodes, 13 subjects (92.9%) had successful defibrillation. The 1 failure was associated with high and lateral shock coil placement. Mean ventricular fibrillation duration was 18.4 ± 5.6 s with a shock impedance of 98.1 ± 19.3 ohms. Of the 11 subjects with coil-patch electrograms, the average R-wave amplitude during sinus rhythm was 3.0 ± 1.4 mV. Conclusions These preliminary data demonstrate that substernal defibrillation is feasible and successful defibrillation can be achieved with the shock energy available in current transvenous ICDs. This may open new alternatives to extravascular ICD therapy.

Background The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to defibrillate ventricular arrhythmias, avoiding drawbacks of transvenous leads. The global EFFORTLESS S-ICD (Evaluation oF FactORs ImpacTing CLinical Outcome and Cost EffectiveneSS of the S-ICD) registry is collecting outcomes in 985 patients during a 5-year follow-up. Objectives The primary goal of the EFFORTLESS registry is to determine the safety of the S-ICD by evaluating complications and inappropriate shock rate. Methods This is the first report on the full patient cohort and study endpoints with follow-up ≥1 year. The predefined endpoints are 30- and 360-day complications, and shocks for atrial fibrillation or supraventricular tachycardia. Results Patients were followed for 3.1 ± 1.5 years and 82 completed the study protocol 5-year visit. Average age was 48 years, 28% were women, ejection fraction was 43 ± 18%, and 65% had a primary prevention indication. The S-ICD system and procedure complication rate was 4.1% at 30 days and 8.4% at 360 days. The 1-year complication rate trended toward improvement from the first to last quartile of enrollment (11.3% [quartile 1]) to 7.8% [quartile 2], 6.6% [quartile 3], and 7.4% [quartile 4]; quartile 1 vs. quartiles 2 to 4; p = 0.06). Few device extractions occurred due to need for antitachycardia (n = 5), or biventricular (n = 4) or bradycardia pacing (n = 1). Inappropriate shocks occurred in 8.1% at 1 year and 11.7% after 3.1 years. At implant, 99.5% of patients had a successful conversion of induced ventricular tachycardia or ventricular fibrillation. The 1- and 5-year rates of appropriate shock were 5.8% and 13.5%, respectively. Conversion success for discrete spontaneous episodes was 97.4% overall. Conclusions This registry demonstrates that the S-ICD fulfills predefined endpoints for safety and efficacy. Midterm performance rates on complications, inappropriate shocks, and conversion efficacy were comparable to rates observed in transvenous implantable cardioverter-defibrillator studies. (Evaluation oF Factors ImpacTing CLinical Outcome and Cost EffectiveneSS of the S-ICD [The EFFORTLESS S-ICD Registry]; NCT01085435 )