Long-Term Outcomes of Resynchronization-Defibrillation for Heart Failure.

BACKGROUND: The Resynchronization-Defibrillation for Ambulatory Heart Failure Trial (RAFT) showed a greater benefit with respect to mortality at 5 years among patients who received cardiac-resynchronization therapy (CRT) than among those who received implantable cardioverter-defibrillators (ICDs). However, the effect of CRT on long-term survival is not known. METHODS: We randomly assigned patients with New York Heart Association (NYHA) class II or III heart failure, a left ventricular ejection fraction of 30% or less, and an intrinsic QRS duration of 120 msec or more (or a paced QRS duration of 200 msec or more) to receive either an ICD alone or a CRT defibrillator (CRT-D). We assessed long-term outcomes among patients at the eight highest-enrolling participating sites. The primary outcome was death from any cause; the secondary outcome was a composite of death from any cause, heart transplantation, or implantation of a ventricular assist device. RESULTS: The trial enrolled 1798 patients, of whom 1050 were included in the long-term survival trial; the median duration of follow-up for the 1050 patients was 7.7 years (interquartile range, 3.9 to 12.8), and the median duration of follow-up for those who survived was 13.9 years (interquartile range, 12.8 to 15.7). Death occurred in 405 of 530 patients (76.4%) assigned to the ICD group and in 370 of 520 patients (71.2%) assigned to the CRT-D group. The time until death appeared to be longer for those assigned to receive a CRT-D than for those assigned to receive an ICD (acceleration factor, 0.80; 95% confidence interval, 0.69 to 0.92; P = 0.002). A secondary-outcome event occurred in 412 patients (77.7%) in the ICD group and in 392 (75.4%) in the CRT-D group. CONCLUSIONS: Among patients with a reduced ejection fraction, a widened QRS complex, and NYHA class II or III heart failure, the survival benefit associated with receipt of a CRT-D as compared with ICD appeared to be sustained during a median of nearly 14 years of follow-up. (RAFT ClinicalTrials.gov number, NCT00251251.).

Efficacy and Safety of an Extravascular Implantable Cardioverter-Defibrillator.

BACKGROUND: The extravascular implantable cardioverter-defibrillator (ICD) has a single lead implanted substernally to enable pause-prevention pacing, antitachycardia pacing, and defibrillation energy similar to that of transvenous ICDs. The safety and efficacy of extravascular ICDs are not yet known. METHODS: We conducted a prospective, single-group, nonrandomized, premarket global clinical study involving patients with a class I or IIa indication for an ICD, all of whom received an extravascular ICD system. The primary efficacy end point was successful defibrillation at implantation. The efficacy objective would be met if the lower boundary of the one-sided 97.5% confidence interval for the percentage of patients with successful defibrillation was greater than 88%. The primary safety end point was freedom from major system- or procedure-related complications at 6 months. The safety objective would be met if the lower boundary of the one-sided 97.5% confidence interval for the percentage of patients free from such complications was greater than 79%. RESULTS: A total of 356 patients were enrolled, 316 of whom had an implantation attempt. Among the 302 patients in whom ventricular arrhythmia could be induced and who completed the defibrillation testing protocol, the percentage of patients with successful defibrillation was 98.7% (lower boundary of the one-sided 97.5% confidence interval [CI], 96.6%; P<0.001 for the comparison with the performance goal of 88%); 299 of 316 patients (94.6%) were discharged with a working ICD system. The Kaplan-Meier estimate of the percentage of patients free from major system- or procedure-related complications at 6 months was 92.6% (lower boundary of the one-sided 97.5% CI, 89.0%; P<0.001 for the comparison with the performance goal of 79%). No major intraprocedural complications were reported. At 6 months, 25 major complications were observed, in 23 of 316 patients (7.3%). The success rate of antitachycardia pacing, as assessed with generalized estimating equations, was 50.8% (95% CI, 23.3 to 77.8). A total of 29 patients received 118 inappropriate shocks for 81 arrhythmic episodes. Eight systems were explanted without extravascular ICD replacement over the 10.6-month mean follow-up period. CONCLUSIONS: In this prospective global study, we found that extravascular ICDs were implanted safely and were able to detect and terminate induced ventricular arrhythmias at the time of implantation. (Funded by Medtronic; ClinicalTrials.gov number, NCT04060680.).

18F-FDG PET/CT and radiolabeled leukocyte SPECT/CT imaging for the evaluation of cardiovascular infection in the multimodality context: ASNC Imaging Indications (ASNC I2) Series Expert Consensus Recommendations from ASNC, AATS, ACC, AHA, ASE, EANM, HRS, IDSA, SCCT, SNMMI, and STS.

This document on cardiovascular infection, including infective endocarditis, is the first in the American Society of Nuclear Cardiology Imaging Indications (ASNC I2) series to assess the role of radionuclide imaging in the multimodality context for the evaluation of complex systemic diseases with multi-societal involvement including pertinent disciplines. A rigorous modified Delphi approach was used to determine consensus clinical indications, diagnostic criteria, and an algorithmic approach to diagnosis of cardiovascular infection including infective endocarditis. Cardiovascular infection incidence is increasing and is associated with high morbidity and mortality. Current strategies based on clinical criteria and an initial echocardiographic imaging approach are effective but often insufficient in complicated cardiovascular infection. Radionuclide imaging with 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and single photon emission computed tomography/CT leukocyte scintigraphy can enhance the evaluation of suspected cardiovascular infection by increasing diagnostic accuracy, identifying extracardiac involvement, and assessing cardiac implanted device pockets, leads, and all portions of ventricular assist devices. This advanced imaging can aid in key medical and surgical considerations. Consensus diagnostic features include focal/multi-focal or diffuse heterogenous intense 18F-FDG uptake on valvular and prosthetic material, perivalvular areas, device pockets and leads, and ventricular assist device hardware persisting on non-attenuation corrected images. There are numerous clinical indications with a larger role in prosthetic valves, and cardiac devices particularly with possible infective endocarditis or in the setting of prior equivocal or non-diagnostic imaging. Illustrative cases incorporating these consensus recommendations provide additional clarification. Future research is necessary to refine application of these advanced imaging tools for surgical planning, to identify treatment response, and more.

The clinical and economic impact of extended battery longevity of a substernal extravascular implantable cardioverter defibrillator.

INTRODUCTION: The extravascular implantable cardioverter defibrillator (EV ICD) has extended projected battery longevity compared to the subcutaneous implantable cardioverter defibrillator (S-ICD). This study used modeling to characterize the need for generator changes, long-term complications, and overall costs for both the EV ICD and S-ICD in healthcare systems of various countries. METHODS: Battery longevity data were modeled using a Markov model from averages reported in device labeling for the S-ICD and with engineering estimates based on real life usage from EV ICD Pivotal Study patient data to introduce variability. Clinical demographic data were derived from published literature. The primary outcomes were defined as the number of generator replacement surgeries, complications, and total healthcare system costs due to battery depletion over the expected lifetime of patients receiving EV ICD or S-ICD therapy. RESULTS: Average modeled battery longevity was determined to be 7.3 years for the S-ICD versus 11.8 years for the EV ICD. The probability of a complication after a replacement procedure was 1.4%, with an operative mortality rate of 0.02%. The use of EV ICD was associated with 1.4-1.6 fewer replacements on average over an expected patient lifetime as compared to S-ICD and a 24.3%-26.0% reduction in cost. A one-way sensitivity analysis of the model for the US healthcare system found that use of an EV ICD resulted in a reduction in replacement surgeries of greater than 1 (1.1-1.6) along with five-figure cost savings in all scenarios ($18 602-$40 948). CONCLUSION: The longer projected battery life of the EV ICD has the potential to meaningfully reduce long-term morbidity and healthcare resources related to generator changes from the perspective of multiple diverse healthcare systems.

Patient-reported quality of life and acceptance of the extravascular implantable cardioverter-defibrillator: Results from pivotal study.

INTRODUCTION: The pivotal study of the extravascular implantable cardioverter-defibrillator (EV ICD) recently demonstrated primary efficacy and safety endpoints comparable to previous ICD systems. Patient experience with this novel device has not been reported. The current study examined the standardized patient-reported outcome (PRO) metrics of quality of life (QOL) and patient acceptance of the device. METHODS: The EV ICD Pivotal Study was a prospective, single-arm, nonrandomized, global, premarket approval trial. Patients completed the 12-Item Short Form Survey (SF-12) QOL surveys at baseline and at 6 months following implant. Additionally, patients completed the Florida Patient Acceptance Survey (FPAS) QOL survey at 6 months. RESULTS: From baseline to 6 months, patients within the EV ICD Pivotal Study (n = 247) reported statistically significant SF-12 improvements in physical QOL (45.4 ± 9.4 vs. 46.8 ± 9.1 respectively, p = .020) and no changes in mental QOL (49.3 ± 10.4 vs. 50.5 ± 9.7, p = .061). No differences were noted by sex, atrial fibrillation, or the experience of ICD shock. EV ICD patients reported better total FPAS patient acceptance of their ICD than TV-ICD or S-ICD patients using historical norms comparisons (80.4 ± 15.7 vs. 70.2 ± 17.8, p < .0001 for S-ICD and 73.0 ± 17.4, p = .004 for TV-ICD). CONCLUSION: The initial PROs for EV ICD patients indicated that patients had improvements in physical QOL from baseline to 6-month follow-up and markedly better overall acceptance of their ICD compared to a previous study with S-ICD and TV-ICD data. These initial results suggest that the EV ICD is evaluated positively by patients.

18F-FDG PET/CT and radiolabeled leukocyte SPECT/CT imaging for the evaluation of cardiovascular infection in the multimodality context: ASNC Imaging Indications (ASNC I2) Series Expert Consensus Recommendations from ASNC, AATS, ACC, AHA, ASE, EANM, HRS, IDSA, SCCT, SNMMI, and STS.

This document on cardiovascular infection, including infective endocarditis, is the first in the American Society of Nuclear Cardiology Imaging Indications (ASNC I2) series to assess the role of radionuclide imaging in the multimodality context for the evaluation of complex systemic diseases with multi-societal involvement including pertinent disciplines. A rigorous modified Delphi approach was used to determine consensus clinical indications, diagnostic criteria, and an algorithmic approach to diagnosis of cardiovascular infection including infective endocarditis. Cardiovascular infection incidence is increasing and is associated with high morbidity and mortality. Current strategies based on clinical criteria and an initial echocardiographic imaging approach are effective but often insufficient in complicated cardiovascular infection. Radionuclide imaging with 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (CT) and single photon emission computed tomography/CT leukocyte scintigraphy can enhance the evaluation of suspected cardiovascular infection by increasing diagnostic accuracy, identifying extracardiac involvement, and assessing cardiac implanted device pockets, leads, and all portions of ventricular assist devices. This advanced imaging can aid in key medical and surgical considerations. Consensus diagnostic features include focal/multi-focal or diffuse heterogenous intense 18F-FDG uptake on valvular and prosthetic material, perivalvular areas, device pockets and leads, and ventricular assist device hardware persisting on non-attenuation corrected images. There are numerous clinical indications with a larger role in prosthetic valves, and cardiac devices particularly with possible infective endocarditis or in the setting of prior equivocal or non-diagnostic imaging. Illustrative cases incorporating these consensus recommendations provide additional clarification. Future research is necessary to refine application of these advanced imaging tools for surgical planning, to identify treatment response, and more.

Efficacy and safety of supraclavicular and pectoralis nerve blocks as primary peri-procedural analgesia for cardiac electronic device implantation: A pilot study.

BACKGROUND: Cardiac implantable electronic devices (CIEDs) are routinely implanted using intravenous drugs for sedation. However, some patients are poor candidates for intravenous sedation. OBJECTIVE: We present a case series demonstrating the safety and efficacy of a novel, ultrasound-guided nerve block technique that allows for pre-pectoral CIED implantation. The targets are the supraclavicular nerve (SCN) and pectoral nerve (PECS1). METHODS: We enrolled 20 patients who were planned for new CIED implantation. Following US-localization of the SCN and PECS1, local anesthetic (LA) was instilled at least 30-60 min pre-procedure. Successful nerve block was determined if < 5 mL of intraprocedural LA was used, along with lack of sensation with skin and deep tissue pinprick. Optional sedation was offered to patients' pre-procedure if discomfort was reported. RESULTS: Seventeen patients (85%) had a successful periprocedural nerve block, with only three patients exceeding 5 mL of LA. SCN and PECS1 success occurred in 19 (95%) and 18 (90%) patients, respectively. The overall success of nerve block by fulfilling all the criteria was demonstrated in 17 out of 20 patients (85%). Patients who reported no pain (VAS score = 0) were distributed as follows: 13 patients (65%) in the immediate post-procedure interval, 18 patients (90%) at the 1 h post-implant interval, and 14 patients (70%) at the 24 h post- implant interval. The median cumulative VAS score was 0 (IQR = 0 - 1). There were no reported significant adverse effects. CONCLUSION: SCN and PECS1 nerve blocks are safe and effective for patients undergoing CIED implantation to minimize or eliminate the use of intravenous sedation.

The development of the extravascular defibrillator with substernal lead placement: A new Frontier for device-based treatment of sudden cardiac arrest.

INTRODUCTION: The extravascular implantable cardioverter-defibrillato (EV ICD) system with substernal lead placement is a novel nontransvenous 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 but requires a new procedure for implantation with a safety profile under evaluation. METHODS: This paper summarizes the development of the EV ICD, including the preclinical and clinical evaluations that have contributed to the system and procedural refinements to date. RESULTS: Extensive preclinical research evaluations and four 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 antitachycardia and asystole pacing in a single system.

An International Multicenter Evaluation of Inheritance Patterns, Arrhythmic Risks, and Underlying Mechanisms of CASQ2-Catecholaminergic Polymorphic Ventricular Tachycardia.

BACKGROUND: Genetic variants in calsequestrin-2 (CASQ2) cause an autosomal recessive form of catecholaminergic polymorphic ventricular tachycardia (CPVT), although isolated reports have identified arrhythmic phenotypes among heterozygotes. Improved insight into the inheritance patterns, arrhythmic risks, and molecular mechanisms of CASQ2-CPVT was sought through an international multicenter collaboration. METHODS: Genotype-phenotype segregation in CASQ2-CPVT families was assessed, and the impact of genotype on arrhythmic risk was evaluated using Cox regression models. Putative dominant CASQ2 missense variants and the established recessive CASQ2-p.R33Q variant were evaluated using oligomerization assays and their locations mapped to a recent CASQ2 filament structure. RESULTS: A total of 112 individuals, including 36 CPVT probands (24 homozygotes/compound heterozygotes and 12 heterozygotes) and 76 family members possessing at least 1 presumed pathogenic CASQ2 variant, were identified. Among CASQ2 homozygotes and compound heterozygotes, clinical penetrance was 97.1% and 26 of 34 (76.5%) individuals had experienced a potentially fatal arrhythmic event with a median age of onset of 7 years (95% CI, 6-11). Fifty-one of 66 CASQ2 heterozygous family members had undergone clinical evaluation, and 17 of 51 (33.3%) met diagnostic criteria for CPVT. Relative to CASQ2 heterozygotes, CASQ2 homozygote/compound heterozygote genotype status in probands was associated with a 3.2-fold (95% CI, 1.3-8.0; P=0.013) increased hazard of a composite of cardiac syncope, aborted cardiac arrest, and sudden cardiac death, but a 38.8-fold (95% CI, 5.6-269.1; P<0.001) increased hazard in genotype-positive family members. In vitro turbidity assays revealed that p.R33Q and all 6 candidate dominant CASQ2 missense variants evaluated exhibited filamentation defects, but only p.R33Q convincingly failed to dimerize. Structural analysis revealed that 3 of these 6 putative dominant negative missense variants localized to an electronegative pocket considered critical for back-to-back binding of dimers. CONCLUSIONS: This international multicenter study of CASQ2-CPVT redefines its heritability and confirms that pathogenic heterozygous CASQ2 variants may manifest with a CPVT phenotype, indicating a need to clinically screen these individuals. A dominant mode of inheritance appears intrinsic to certain missense variants because of their location and function within the CASQ2 filament structure.

The extravascular implantable cardioverter-defibrillator: The pivotal study plan.

BACKGROUND: Transvenous implantable cardioverter 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 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, multicenter, single-arm, nonrandomized, premarket 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 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.

A simple maneuver to determine if septal accessory pathway ablation requires a left atrial approach.

INTRODUCTION: Septal accessory pathway (AP) ablation can be challenging due to the complex anatomy of the septal region. The decision to access the left atrium (LA) is often made after failure of ablation from the right. We sought to establish whether the difference between ventriculo-atrial (VA) time during right ventricular (RV) apical pacing versus the VA during tachycardia would help establish the successful site for ablation of septal APs. METHODS: Intracardiac electrograms of patients with orthodromic reciprocating tachycardia (ORT) using a septal AP with successful catheter ablation were reviewed. The ∆VA was the difference between the VA interval during RV apical pacing and the VA interval during ORT. The difference in the VA interval during right ventricular entrainment and ORT (StimA-VA) was also measured. RESULTS: The median ∆VA time was significantly less in patients with a septal AP ablated on the right side compared with patients with a septal AP ablated on the left side (12 ± 19 vs. 56 ± 10 ms, p < .001). The StimA-VA was significantly different between the two groups (22 ± 14 vs. 53 ± 9 ms, p < .001). The ∆VA and StimA-VA were always ≤ 40 ms in patients with non-decremental septal APs ablated from the right side and always greater than 40 ms in those with septal APs ablated from the left. CONCLUSION: ΔVA and StimA-VA values identified with RV apical pacing in the setting of ORT involving a septal AP predict when left atrial access will be necessary for successful ablation.

Pulmonary Vein Isolation With Incomplete Antral Ablation Lines: Is More Ablation Necessary? Results of a Randomized Trial.

BACKGROUND: A full circumferential set of antral lesions is not always required for bidirectional pulmonary vein conduction block. It is unknown whether a partial lesion set that isolates the veins will have clinical success rates similar to a full circumferential lesion set, and if procedural times or procedural risk will be affected. METHODS: We performed a prospective, randomized clinical trial to test the hypothesis that a partial lesion set that isolates the pulmonary veins has comparable clinical success rate and shorter procedure times compared to a strategy of completing the circumferential lesion set once the veins are isolated. RESULTS: A total of 119 patients were enrolled, 59 randomized to circumferential ablation, and 60 to segmental. Mean age was 58.3 ± 10.1, 77% male. Mean procedure time was 221.0 ± 46.9 minutes in circumferential and 224.7 ± 51.3 in segmental (P = 0.68). Twelve-month freedom from AF recurrence was 61.3% overall, 64.4% in circumferential, and 58.3% in segmental (P = 0.50). Among 25 segmental patients with AF recurrence, 23 underwent second ablation. Among 33 areas of conduction recovery, 23 (70%) occurred in segments ablated at first procedure and 10 (30%) in segments not previously ablated, suggesting reversible conduction block from edema. CONCLUSION: No difference in AF recurrence or procedure time is detectable in a sample of 119 patients randomized to segmental or circumferential antral ablation to achieve pulmonary vein isolation. Second ablation procedures confirmed that some antral sites do not require ablation. A segmental approach results in unacceptably high rates of untargeted or recovered antral sites to make this approach feasible.

Reduced Uptake of Family Screening in Genotype-Negative Versus Genotype-Positive Long QT Syndrome.

The acceptance and yield of family screening in genotype-negative long QT syndrome (LQTS) remains incompletely characterized. In this study of family screening for phenotype-definite Long QT Syndrome (LQTS, Schwartz score ≥3.5), probands at a regional Inherited Cardiac Arrhythmia clinic were reviewed. All LQTS patients were offered education by a qualified genetic counselor, along with materials for family screening including electronic and paper correspondence to provide to family members. Thirty-eight qualifying probands were identified and 20 of these had family members who participated in cascade screening. The acceptance of screening was found to be lower among families without a known pathogenic mutation (33 vs. 77 %, p = 0.02). A total of 52 relatives were screened; fewer relatives were screened per index case when the proband was genotype-negative (1.7 vs. 3.1, p = 0.02). The clinical yield of screening appeared to be similar irrespective of gene testing results (38 vs. 33 %, p = 0.69). Additional efforts to promote family screening among gene-negative long QT families may be warranted.

Advanced left-ventricular lead placement techniques for cardiac resynchronization therapy.

PURPOSE OF REVIEW: Due to complex venous anatomy and limitations in lead delivery tools and technology, the incidence of failed left-ventricular lead implants continues to be as high as 10%. RECENT FINDINGS: A move towards an interventional approach to left-ventricular lead implantation has provided viable alternatives to surgical lead implantation. The use of telescoping sheaths, gooseneck snares and percutaneous balloon venoplasty may reduce procedural times by facilitating lead delivery despite challenging venous anatomy. In addition, recent advancements in left-ventricular lead technology now allow implanting physicians to overcome commonly encountered obstacles such as high thresholds and phrenic nerve stimulation, without having to move the lead from a stable position. For those with suboptimal or inaccessible coronary vein targets, a simplified transseptal endocardial implant approach has also been described. SUMMARY: These recent advances in implant techniques and left-ventricular lead technology provide promising solutions to commonly encountered procedural obstacles in the implementation of resynchronization therapy. These alternative strategies will hopefully reduce the rate of failed implants and referrals for surgical epicardial leads.

Extensive Thrombosis Following Lead Extraction: Further Justification for Routine Post-operative Anticoagulation.

Lead extraction is becoming increasingly common as indications for pacing and ICD insertion expand. Periop management varies between extraction centers, and no clinical guidelines have addressed the need for perioperative anticoagulation. We report a case of massive thrombosis which occurred shortly after laser lead extraction and is undoubtedly related to the trauma of the extraction and ensuing hypercoagulabiilty. Routine post-operative anticoagulation has been advocated as a means to prevent access vein (subclavian) stenosis, but many centres do not employ a routine post-extraction anticoagulation strategy. Pulmonary embolism following lead extraction is a known complication of this procedure and late mortality following lead extraction is a significant and underappreciated problem. We propose that further research attention should be directed at addressing the issue of routine post-extraction anticoagulation.

Extravascular Implantable Cardioverter-Defibrillator Sensing and Detection in a Large Global Population.

BACKGROUND: The extravascular (EV) implantable cardioverter-defibrillator (ICD) includes features to address sensing and arrhythmia detection challenges presented by its substernal lead location. OBJECTIVES: In this study, the authors sought to evaluate sensing and detection performance in 299 patients discharged with an EV-ICD in the global pivotal study. METHODS: We reviewed and adjudicated all induced ventricular fibrillation (VF) episodes and spontaneous device-stored episodes that satisfied rate and duration criteria in a programmed ventricular tachycardia (VT)/VF therapy zone. RESULTS: At implantation, all EV-ICDs detected induced VF at the programmed sensitivity; 95.9% detected VF with a 3× safety margin. In follow-up, EV-ICDs detected all 59 VT/VF episodes that sustained until therapy. Of 1,034 non-VT/VF episodes, oversensing caused 87.9% and supraventricular tachycardia caused 12.1%. Therapy was withheld in 80.9%, aborted in 10.6%, and delivered in 8.5%. The most common causes of oversensing were myopotentials (61.2%) and P-wave oversensing (PWOS) (19.9%). Inappropriate shocks occurred in only 3.2% of myopotential episodes, but in 21.8% of PWOS episodes. Myopotential oversensing was more common with Ring-Can sensing (P < 0.0001) and correlated with low R-wave amplitude (P < 0.0001). PWOS occurred almost exclusively with Ring1-Ring2 sensing (P = 0.0001) and began with transient decrease in R-wave or increase in P-wave amplitude (P < 0.0001). In software emulation, a new PWOS discriminator significantly reduced total inappropriate detections. CONCLUSIONS: In a global population, EV-ICD detected induced and spontaneous VT/VF accurately. Although discriminators withheld detection from most non-VT/VF episodes, inappropriate shocks were common. The most common cause was PWOS, which may be reduced by optimizing sensing at implantation and incorporation of the PWOS discriminator, which is now in the current device. (Extravascular ICD Pivotal Study [EV ICD]; NCT04060680).

Navigating the Landscape of Medical Device Advisories: A Special Report From the Canadian Heart Rhythm Society Device Advisory Committee.

Cardiac implantable electronic devices (CIEDs) are often important for regulating cardiac rate and rhythm. Pacemakers and defibrillators are among the top 10 most implanted medical devices, with > 1.5 million devices implanted annually. Although millions of patients have benefited with improved quality of life and survival, CIED systems are becoming increasingly complex and do not always perform according to expectations. Advisory notices communicate important information about the safety and performance of a medical device to health care providers and patients. Medical device recalls are common, with > 35 unique device recalls in the past 5 years. From an ethical standpoint, CIED recalls highlight a range of considerations including the consent process, duty to report, how best to promote autonomous decision-making, trust in the health care system, as well as disproportionate effects of these considerations on equity-deserving groups. The purpose of the current article is to review and advise regarding the process around medical device advisory and recall, with a specific focus on clinicians caring for patients affected by these devices. We have sought the input of a lawyer, a patient advocacy group, and an ethicist to guide the clinical management of, and communications regarding, device recalls and advisories. Diligent surveillance and a clear, transparent patient consent process regarding these small but potentially serious device anomalies is paramount in ensuring patients believe they are safe and informed. Meaningful patient engagement helps to ensure optimal communication and disclosure mechanisms before implantation and throughout follow-up, accessibility of information in the initial implant and recall action process, and trust in health care systems and providers.