A Modular Communicative Leadless Pacing-Defibrillator System.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (ICD) is associated with fewer lead-related complications than a transvenous ICD; however, the subcutaneous ICD cannot provide bradycardia and antitachycardia pacing. Whether a modular pacing-defibrillator system comprising a leadless pacemaker in wireless communication with a subcutaneous ICD to provide antitachycardia and bradycardia pacing is safe remains unknown. METHODS: We conducted a multinational, single-group study that enrolled patients at risk for sudden death from ventricular arrhythmias and followed them for 6 months after implantation of a modular pacemaker-defibrillator system. The safety end point was freedom from leadless pacemaker-related major complications, evaluated against a performance goal of 86%. The two primary performance end points were successful communication between the pacemaker and the ICD (performance goal, 88%) and a pacing threshold of up to 2.0 V at a 0.4-msec pulse width (performance goal, 80%). RESULTS: We enrolled 293 patients, 162 of whom were in the 6-month end-point cohort and 151 of whom completed the 6-month follow-up period. The mean age of the patients was 60 years, 16.7% were women, and the mean (±SD) left ventricular ejection fraction was 33.1±12.6%. The percentage of patients who were free from leadless pacemaker-related major complications was 97.5%, which exceeded the prespecified performance goal. Wireless-device communication was successful in 98.8% of communication tests, which exceeded the prespecified goal. Of 151 patients, 147 (97.4%) had pacing thresholds of 2.0 V or less, which exceeded the prespecified goal. The percentage of episodes of arrhythmia that were successfully terminated by antitachycardia pacing was 61.3%, and there were no episodes for which antitachycardia pacing was not delivered owing to communication failure. Of 162 patients, 8 died (4.9%); none of the deaths were deemed to be related to arrhythmias or the implantation procedure. CONCLUSIONS: The leadless pacemaker in wireless communication with a subcutaneous ICD exceeded performance goals for freedom from major complications related to the leadless pacemaker, for communication between the leadless pacemaker and subcutaneous ICD, and for the percentage of patients with a pacing threshold up to 2.0 V at a 0.4-msec pulse width at 6 months. (Funded by Boston Scientific; MODULAR ATP ClinicalTrials.gov NCT04798768.).

Leadless pacemakers at 5-year follow-up: the Micra transcatheter pacing system post-approval registry.

BACKGROUND AND AIMS: Prior reports have demonstrated a favourable safety and efficacy profile of the Micra leadless pacemaker over mid-term follow-up; however, long-term outcomes in real-world clinical practice remain unknown. Updated performance of the Micra VR leadless pacemaker through five years from the worldwide post-approval registry (PAR) was assessed. METHODS: All Micra PAR patients undergoing implant attempts were included. Endpoints included system- or procedure-related major complications and system revision rate for any cause through 60 months post-implant. Rates were compared through 36 months post-implant to a reference dataset of 2667 transvenous pacemaker patients using Fine-Gray competing risk models. RESULTS: 1809 patients were enrolled between July 2015 and March 2018 and underwent implant attempts from 179 centres in 23 countries with a median follow-up period of 51.1 months (IQR: 21.6-64.2). The major complication rate at 60 months was 4.5% [95% confidence interval (CI): 3.6%-5.5%] and was 4.1% at 36 months, which was significantly lower than the 8.5% rate observed for transvenous systems (HR: .47, 95% CI: .36-.61; P < .001). The all-cause system revision rate at 60 months was 4.9% (95% CI: 3.9%-6.1%). System revisions among Micra patients were mostly for device upgrades (41.2%) or elevated thresholds (30.6%). There were no Micra removals due to infection noted over the duration of follow-up. At 36 months, the system revision rate was significantly lower with Micra vs. transvenous systems (3.2% vs. 6.6%, P < .001). CONCLUSIONS: Long-term outcomes with the Micra leadless pacemaker continue to demonstrate low rates of major complications and system revisions and an extremely low incidence of infection.

Electrical storm after left ventricular assist device (LVAD) implantation.

INTRODUCTION: Ventricular tachycardia storm or electrical storm (ES) is a common complication following left ventricular assist device (LVAD) implantation. The factors contributing to ES and outcomes are less studied. The study aimed to determine the factors associated with ES and the probability of survival in patients undergoing LVAD in three tertiary centers over a span of 15 years. METHODS: We performed a retrospective cohort study on all patients who underwent LVAD implantation at the Mayo Clinic (Rochester, Phoenix, and Jacksonville) from January 1, 2006 to December 31, 2020. ES was defined as ≥3 episodes of sustained ventricular tachycardia over a period of 24 h with no identifiable reversible cause. Detailed chart reviews of the electronic health records within the Mayo Clinic and outside medical records were performed. RESULTS: A total of 883 patients who underwent LVAD implantation were included in our study. ES occurred in 7% (n = 61) of patients with a median of 13 days (interquartile range [IQR]: 5-297 days) following surgery. We found 57% of patients (n = 35) developed ES within 30 days, while 43% (n = 26) patients developed ES at a median of 545  (IQR 152-1032) days after surgery. Following ES, 26% of patients died within 1 year. Patients with ES had a significant association with a history of ventricular arrhythmias and implantable cardioverter defibrillator (ICD) shocks before the procedure. ES was significantly associated with reduced survival compared to patients without ES (hazards ratio [HR]: 1.92, 95% CI: 1.39-2.64, p < .001). CONCLUSION: Following LVAD implantation, the rate of ES was 7% with majority of ES occurring within 30 days of LVAD. Risk factors for ES included pre-implant history of ventricular arrhythmias and ICD shock. ES was significantly associated with reduced survival compared to patients without ES.

Arrhythmias in Female Patients: Incidence, Presentation and Management.

There is a growing appreciation for differences in epidemiology, treatment, and outcomes of cardiovascular conditions by sex. Historically, cardiovascular clinical trials have under-represented females, but findings have nonetheless been applied to clinical care in a sex-agnostic manner. Thus, much of the collective knowledge about sex-specific cardiovascular outcomes result from post hoc and secondary analyses. In some cases, these investigations have revealed important sex-based differences with implications for optimizing care for female patients with arrhythmias. This review explores the available evidence related to cardiac arrhythmia care among females, with emphasis on areas in which important sex differences are known or suggested. Considerations related to improving female enrollment in clinical trials as a way to establish more robust clinical evidence for the treatment of females are discussed. Areas of remaining evidence gaps are provided, and recommendations for areas of future research and specific action items are suggested. The overarching goal is to improve appreciation for sex-based differences in cardiac arrhythmia care as 1 component of a comprehensive plan to optimize arrhythmia care for all patients.

Long-term outcomes with abandoning versus extracting sterile leads: A 10-year population-based study.

BACKGROUND: Long-term outcomes of sterile lead management strategies of lead abandonment (LA) or transvenous lead extraction (TLE) remain unclear. METHODS: We performed a retrospective study of a population residing in southeastern Minnesota with follow-up at the Mayo Clinic and its health systems. Patients who underwent LA or TLE of sterile leads from January 1, 2000, to January 1, 2011, and had follow-up for at least 10 years or until their death were included. RESULTS: A total of 172 patients were included in the study with 153 patients who underwent LA and 19 who underwent TLE for sterile leads. Indications for subsequent lead extraction arose in 9.1% (n = 14) of patients with initial LA and 5.3% (n = 1) in patients with initial TLE, after an average of 7 years. Moreover, 28.6% of patients in the LA cohort who required subsequent extraction did not proceed with the extraction, and among those who proceeded, 60% had clinical success and 40% had a clinical failure. Subsequent device upgrades or revisions were performed in 18.3% of patients in the LA group and 31.6% in the TLE group, with no significant differences in procedural challenges (5.2% vs. 5.3%). There was no difference in 10-year survival probability among the LA group and the TLE group (p = .64). CONCLUSION: An initial lead abandonment strategy was associated with more complicated subsequent extraction procedures compared to patients with an initial transvenous lead extraction strategy. However, there was no difference in 10-year survival probability between both lead management approaches.

Left bundle branch area pacing for heart failure patients requiring cardiac resynchronization therapy: A meta-analysis.

INTRODUCTION: Left bundle branch area pacing (LBBP) is a novel conduction system pacing method to achieve effective physiological pacing and an alternative to cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) for patients with heart failure with reduced ejection fraction (HFrEF). We conduted this meta-analysis and systemic review to review current data comparing BVP and LBBP in patients with HFrEF and indications for CRT. METHODS: We searched PubMed/Medline, Web of Science, and Cochrane Library from the inception of the database to November 2022. All studies that compared LBBP with BVP in patients with HFrEF and indications for CRT were included. Two reviewers performed study selection, data abstraction, and risk of bias assessment. We calculated risk ratios (RRs) with the Mantel-Haenszel method and mean difference (MD) with inverse variance using random effect models. We assessed heterogeneity using the I2 index, with I2 > 50% indicating significant heterogeneity. RESULTS: Ten studies (9 observational studies and 1 randomized controlled trial; 616 patients; 15 centers) published between 2020 and 2022 were included. We observed a shorter fluoroscopy time (MD: 9.68, 95% confidence interval [CI]: 4.49-14.87, I2 = 95%, p < .01, minutes) as well as a shorter procedural time (MD 33.68, 95% CI: 17.80-49.55, I2 = 73%, p < .01, minutes) during the implantation of LBBP CRT compared to conventional BVP CRT. LBBP was shown to have a greater reduction in QRS duration (MD 25.13, 95% CI: 20.06-30.20, I2 = 51%, p < .01, milliseconds), a greater left ventricular ejection fraction improvement (MD: 5.80, 95% CI: 4.81-6.78, I2 = 0%, p < .01, percentage), and a greater left ventricular end-diastolic diameter reduction (MD: 2.11, 95% CI: 0.12-4.10, I2 = 18%, p = .04, millimeter). There was a greater improvement in New York Heart Association function class with LBBP (MD: 0.37, 95% CI: 0.05-0.68, I2 = 61%, p = .02). LBBP was also associated with a lower risk of a composite of heart failure hospitalizations (HFH) and all-cause mortality (RR: 0.48, 95% CI: 0.25-0.90, I2 = 0%, p = .02) driven by reduced HFH (RR: 0.39, 95% CI: 0.19-0.82, I2 = 0%, p = .01). However, all-cause mortality rates were low in both groups (1.52% vs. 1.13%) and similar (RR: 0.98, 95% CI: 0.21-4.68, I2 = 0%, p = .87). CONCLUSION: This meta-analysis of primarily nonrandomized studies suggests that LBBP is associated with a greater improvement in left ventricular systolic function and a lower rate of HFH compared to BVP. There was uniformity of these findings in all of the included studies. However, it would be premature to conclude based solely on the current meta-analysis alone, given the limitations stated. Dedicated, well-designed, randomized controlled trials and observational studies are needed to elucidate better the comparative long-term efficacy and safety of LBBP CRT versus BIV CRT.

The subtle tine: Asymptomatic Micra perforation incidentally discovered during cardiac surgery.

A 70-year-old woman with longstanding persistent atrial fibrillation underwent Micra leadless pacemaker implantation and atrioventricular nodal ablation. No postprocedural complications were noted. She subsequently underwent surgical mitral valve replacement 4 years later. During the surgery, Micra tine perforation of the right ventricular free wall was seen. No device revision was performed due to her asymptomatic status and stable pacemaker position/function. Pericardial effusion is a known complication of Micra implantation. The incidence of tine perforation is unknown as many patients may be asymptomatic. The clinical consequences regarding adverse events, device functionality, and explantation/extraction risk profile remain to be determined.

Ventricular arrhythmias in patients with prior aortic valve intervention: Characteristics, ablation and outcomes.

INTRODUCTION: Data regarding ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation in patients with aortic valve (AV) intervention (AVI) is limited. Catheter ablation (CA) can be challenging given perivalvular substrate in the setting of prosthetic valves. We sought to investigate the characteristics, safety, and outcomes of CA in patients with prior AVI and ventricular arrhythmias (VA). METHODS: We identified consecutive patients with prior AVI (replacement or repair) who underwent CA for VT or PVC between 2013 and 2018. We investigated the mechanism of arrhythmia, ablation approach, perioperative complications, and outcomes. RESULTS: We included 34 patients (88% men, mean age 64 ± 10.4 years, left ventricular (LV) ejection fraction 35.2 ± 15.0%) with prior AVI who underwent CA (22 VT; 12 PVC). LV access was obtained through trans-septal approach in all patients except one patient who had percutaneous transapical access. One patient had combined retrograde aortic and trans-septal approach. Scar-related reentry was the dominant mechanism of induced VTs. Two patients had bundle branch reentry VTs. In the VT group, substrate mapping demonstrated heterogeneous scar that involved the peri-AV area in 95%. Despite that, the site of successful ablation included the periaortic region only in 6 (27%) patients. In the PVC group, signal abnormalities consistent with scar in the periaortic area were noted in 4 (33%) patients. In 8 (67%) patients, the successful site of ablation was unrelated to the periaortic area. No procedure-related complications occurred. The survival and recurrence-free survival rate at 1 year tended to be lower in VT group than in PVC group (p = .06 and p = .05, respectively) with a 1-year recurrence-free survival rate of 52.8% and 91.7%, respectively. No arrhythmia-related death was documented on long-term follow-up. CONCLUSION: CA of VAs can be performed safely and effectively in patients with prior AVI.

Outcome and safety of intraoperative defibrillation testing during device replacement: the Simpler trial.

AIMS: Intraoperative defibrillation testing (DT) during implant or replacement of implantable cardioverter-defibrillators (ICDs) has been a matter of debate for many years. This debate was put to rest by the Simple and Nordic ICD trials, and the practice of testing during new implantations has essentially been almost abandoned. Old registries demonstrated an increased incidence of significant findings in DT during replacements. The aim of the present study was to evaluate frequency of significant findings and safety of DT in subjects undergoing device replacement. METHODS AND RESULTS: A prospective observational multi-centre study included consecutive patients undergoing ICD generator replacement. The primary outcome was a failure to terminate induced ventricular fibrillation (VF) with a single shock 10 J below the maximal capacity of the device. Secondary outcomes included complications of DT. Patients were followed-up at 1- and 6-months post-procedure. A total of 92 patients were eligible, and consented to the study, of which 84 underwent DT during battery replacement. The median age was 68 years and 79.8% were males. Induction of VF was successful in 84 patients as was a successful conversion on the first attempt in all. There were no procedure-related complications. During follow up one patient had two appropriate ICD shock events. In four patients, ICD programming was changed. None suffered inappropriate shock. There was no evidence of lead malfunction. Two deaths occurred, none of which was related to arrhythmia. CONCLUSION: The present study found DT was not associated with complications in patients undergoing ICD generator replacement but produced no clinically important information.

One-year outcomes of catheter ablation for atrial fibrillation in young patients.

BACKGROUND: Atrial fibrillation (AF) is relatively less frequent in younger patients (age < 50). Recently, studies have suggested that early restoration of sinus rhythm may lead to improved outcomes compared with rate control, however the efficacy of catheter ablation for AF in young is scarce. METHODS: We included all hospitalized patients between 18 and 50 years with a diagnosis of AF from the Nationwide Readmission Database 2016-2017 from the Healthcare Cost and Utilization Project. Demographic and comorbidity data were collected and analyzed. Outcomes assessed included one-year AF readmission rates, all-cause readmission, ischemic stroke, and all-cause mortality. Subgroup analyses were performed for all demographic and comorbidity variables. RESULTS: Overall, 52,598 patients (medium age 44, interquartile range 38-48, female 25.7%) were included in the study, including 2,146 (4.0%) who underwent catheter ablation for AF. Patients who underwent catheter ablation had a significantly lower rate of readmission for AF or any cause at one year (adjusted hazard ratios (HR) of 0.52 [95% confidence interval (CI): 0.43-0.63] and HR of 0.81 [95% CI: 0.72-0.89], respectively). There was no difference in 1-year readmission for stroke or all-cause mortality between the two groups. Subgroup analyses showed a consistent reduction in the risk of AF readmission among major demographic and comorbidity subgroups. CONCLUSION: Catheter ablation in young patients with AF was associated with a reduction in 1-year AF related and all-cause readmissions. These data merit further prospective investigation for validation, through dedicated registries and multicenter collaborations to include young AF from diverse population.

Association Between Sex and Treatment Outcomes of Atrial Fibrillation Ablation Versus Drug Therapy: Results From the CABANA Trial.

BACKGROUND: Among patients with atrial fibrillation (AF), women are less likely to receive catheter ablation and may have more complications and less durable results. Most information about sex-specific differences after ablation comes from observational data. We prespecified an examination of outcomes by sex in the 2204-patient CABANA trial (Catheter Ablation Versus Antiarrhythmic Drug Therapy for Atrial Fibrillation). METHODS: CABANA randomized patients with AF age ≥65 years or <65 years with ≥1 risk factor for stroke to a strategy of catheter ablation with pulmonary vein isolation versus drug therapy with rate/rhythm control agents. The primary composite outcome was death, disabling stroke, serious bleeding, or cardiac arrest, and key secondary outcomes included AF recurrence. RESULTS: CABANA randomized 819 (37%) women (ablation 413, drug 406) and 1385 men (ablation 695, drug 690). Compared with men, women were older (median age, 69 years versus 67 years for men), were more symptomatic (48% Canadian Cardiovascular Society AF Severity Class 3 or 4 versus 39% for men), had more symptomatic heart failure (42% with New York Heart Association Class ≥II versus 32% for men), and more often had a paroxysmal AF pattern at enrollment (50% versus 39% for men) (P<0.0001 for all). Women were less likely to have ancillary (nonpulmonary vein) ablation procedures performed during the index procedure (55.7% versus 62.2% in men, P=0.043), and complications from treatment were infrequent in both sexes. For the primary outcome, the hazard ratio for those who underwent ablation versus drug therapy was 1.01 (95% CI, 0.62-1.65) in women and 0.73 (95% CI, 0.51-1.05) in men (interaction P value=0.299). The risk of recurrent AF was significantly reduced in patients undergoing ablation compared with those receiving drug therapy regardless of sex, but the effect was greater in men (hazard ratio, 0.64 [95% CI, 0.51-0.82] for women versus hazard ratio, 0.48 [95% CI, 0.40-0.58] for men; interaction P value=0.060). CONCLUSIONS: Clinically relevant treatment-related strategy differences in the primary and secondary clinical outcomes of CABANA were not seen between men and women, and there were no sex differences in adverse events. The CABANA trial results support catheter ablation as an effective treatment strategy for both women and men. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00911508.

Implantable cardioverter defibrillators in patients with orthotopic heart transplant: A multicenter case series.

BACKGROUND: Sudden cardiac death (SCD) is common after orthotopic heart transplant (OHT). No clear guidelines for implantable cardioverter defibrillator (ICD) implantation in OHT patients at high risk for SCD currently exist. OBJECTIVES: To assess the safety, efficacy, and benefit of ICDs and resynchronization therapy post-OHT. We also provide a systematic review of previous reports. METHODS: A retrospective multicenter cohort study within the United States. Patients with ICD post-OHT between 2000 and 2020 were identified. RESULTS: We analyzed 16 patients from 4 centers. The mean standard-deviation (SD) age was 43 (18) years at OHT and 51 (20) years at ICD implantation. The mean (SD) duration from OHT to ICD implantation was 9 (5) years. The mean (SD) left ventricular ejection fraction (LVEF) was 35% (17%). There were 2 (13%) postprocedural complications: 1 hematoma and 1 death. Mean (SD) follow-up was 24 (23) months. Survival rate was 63% (10/16) at 1 year and 56% (9/16) at 2 years, with 6/7 of those who died having LVEF < 35% at the time of the ICD implantation. Patients were more likely to receive appropriate therapy if their ICD was implanted for secondary (5/8) rather than primary (0/8) prevention (p = .007). Of those who did, 4 patients survived to 30 days post-ICD therapy. Severe CAV was not associated with the rate of appropriate therapy. CONCLUSIONS: Beneficial outcomes were observed when ICDs were implanted for secondary prevention only, and in patients with higher baseline LVEF. We also observed benefits with resynchronization therapy.

Cardiac resynchronization therapy response in cardiac sarcoidosis.

INTRODUCTION: Cardiac sarcoidosis (CS) is a nonischemic cardiomyopathy (NICM) characterized by infiltration of noncaseating granulomas involving the heart with highly variable clinical manifestations that can include conduction abnormalities and systolic heart failure. Cardiac resynchronization therapy (CRT) has shown significant promise in NICM, though little is known about its efficacy in patients with CS. OBJECTIVE: To determine if CRT improved cardiac remodeling in patients with CS. METHODS: We retrospectively reviewed all patients with a clinical or histological diagnosis of CS who underwent CRT implantation at the Mayo Clinic enterprise from 2000 to 2021. Baseline characteristics, imaging parameters, heart failure hospitalizations and need for advanced therapies, and major adverse cardiac events (MACE) were assessed. RESULTS: Our cohort was comprised of 55 patients with 61.8% male and a mean age of 58.7 ± 10.9 years. Eighteen (32.7%) patients had definite CS, 21 (38.2%) had probable CS, while 16 (29.1%) had presumed CS, and 26 (47.3%) with extracardiac sarcoidosis. The majority underwent CRT-D implantation (n = 52, 94.5%) and 3 (5.5%) underwent CRT-P implantation with 67.3% of implanted devices being upgrades from prior pacemakers or implantable cardioverter defibrillators. At 6 months postimplantation there was no significant improvement in ejection fraction (34.8 ± 10.9% vs. 37.7 ± 14.2%, p = .331) or left ventricular end-diastolic diameter (58.5 ± 10.2 vs. 57.5 ± 8.1 mm, p = .236), though mild improvement in left ventricular end systolic diameter (49.1 ± 9.9 vs. 45.7± 9.9 mm, p < .0001). Within the first 6 months postimplantation, 5 (9.1%) patients sustained a heart failure hospitalization. At a mean follow-up of 4.1± 3.7 years, 14 (25.5%) patients experienced a heart failure hospitalization, 11 (20.0%) underwent cardiac transplantation, 1 (1.8%) underwent left ventricular assist device implantation and 7 (12.7%) patients died. CONCLUSIONS: Our findings suggest variable response to CRT in patients with CS with no overall improvement in ventricular function within 6 months and a substantial proportion of patients progressing to advanced heart failure therapies.

A real-world experience of atrioventricular synchronous pacing with leadless ventricular pacemakers.

AIMS: The MicraTM transcatheter pacing system (TPS) (Medtronic) is the only leadless pacemaker that promotes atrioventricular (AV) synchrony via accelerometer-based atrial sensing. Data regarding the real-world experience with this novel system are scarce. We sought to characterize patients undergoing MicraTM -AV implants, describe percentage AV synchrony achieved, and analyze the causes for suboptimal AV synchrony. METHODS: In this retrospective cohort study, electronic medical records from 56 consecutive patients undergoing MicraTM -AV implants at the Mayo Clinic sites in Minnesota, Florida, and Arizona with a minimum follow-up of 3 months were reviewed. Demographic data, comorbidities, echocardiographic data, and clinical outcomes were compared among patients with and without atrial synchronous ventricular pacing (AsVP) ≥ 70%. RESULTS: Sixty-five percent of patients achieved AsVP ≥ 70%. Patients with adequate AsVP had smaller body mass indices, a lower proportion of congestive heart failure, and prior cardiac surgery. Echocardiographic parameters and procedural characteristics were similar across the two groups. Active device troubleshooting was associated with higher AsVP. The likely reasons for low AsVP were small A4-wave amplitude, high ventricular pacing burden, and inadequate device reprogramming. Importantly, in patients with low AsVP, subjective clinical worsening was not noted during follow-up. CONCLUSION: With the increasing popularity of leadless pacemakers, it is paramount for device implanting teams to be familiar with common predictors of AV synchrony and troubleshooting with MicraTM -AV devices.

A wearable cardioverter defibrillator with a low false alarm rate.

INTRODUCTION: A wearable cardioverter defibrillator (WCD) is indicated in appropriate patients to reduce the risk for sudden cardiac death. Challenges for patients wearing a WCD have been frequent false shock alarms primarily due to electrocardiogram noise and wear discomfort. The objective of this study was to test a contemporary WCD designed for reduced false shock alarms and improved comfort. METHODS: One hundred and thirty patients with left ventricular ejection fraction ≤40% and an active implantable cardioverter defibrillator (ICD) were fitted with the ASSURE WCD (Kestra Medical Technologies) and followed for 30 days. WCD detection was enabled and shock alarm markers recorded, but shocks and shock alarms were disabled. All WCD episodes and ICD ventricular tachycardia/ventricular fibrillation (VT/VF) episodes were adjudicated. The primary endpoint was the false-positive shock alarm rate with a performance goal of 1 every 3.4 days (0.29 per patient-day). RESULTS: Of 163 WCD episodes, 4 were VT/VF and 159 non-VT/VF (121 rhythms with noise, 32 uncertain with noise, 6 atrial flutter without noise). Only three false-positive shock alarm markers were recorded; one false-positive shock alarm every 1333 patient-days (0.00075 per patient-day, 95% confidence interval: 0.00015-0.00361; p < .001). No ICD recorded VT/VF episodes meeting WCD detection criteria (≥170 bpm for ≥20 s) were missed by the WCD during 3501 patient-days of use. Median wear was 31.0 days (interquartile range [IQR] 2.0) and median daily use 23.0 h (IQR 1.7). Adverse events were mostly mild: skin irritation (19.4%) and musculoskeletal discomfort (8.5%). CONCLUSION: The ASSURE WCD demonstrated a low false-positive shock alarm rate, low patient-reported discomfort, and no serious adverse events.

Characteristics and outcomes of ventricular tachycardia and premature ventricular contractions ablation in patients with prior mitral valve surgery.

BACKGROUND: Data regarding ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation following mitral valve surgery (MVS) is limited. Catheter ablation (CA) can be challenging given perivalvular substrate in the setting of mitral annuloplasty or prosthetic valves. OBJECTIVE: To investigate the characteristics, safety, and outcomes of radiofrequency CA in patients with prior MVS and ventricular arrhythmias (VA). METHODS: We identified consecutive patients with prior MVS who underwent CA for VT or PVC between January 2013 and December 2018. We investigated the mechanism of arrhythmia, ablation approach, peri-operative complications, and outcomes. RESULTS: In our cohort, 31 patients (77% men, mean age 62.3 ± 10.8 years, left ventricular ejection fraction 39.2 ± 13.9%) with prior MVS underwent CA (16 VT; 15 PVC). Access to the left ventricle was via transseptal approach in 17 patients, and a retrograde aortic approach was used in 13 patients. A combined transseptal and retrograde aortic approach was used in one patient, and a percutaneous epicardial approach was combined with trans-septal approach in one patient. Heterogenous scar regions were present in 94% of VT patients and scar-related reentry was the dominant mechanism of VT. Forty-seven percent of PVC patients had abnormal substrate at the site targeted for ablation. Clinical VA substrates involved the peri-mitral area in six patients with VT and five patients with PVC ablation. No procedure-related complications were reported. The overall recurrence-free rate at 1-year was 72.2%; 67% in the VT group and 78% in the PVC group. No arrhythmia-related death was documented on long-term follow-up. CONCLUSION: CA of VAs can be performed safely and effectively in patients with MVS.

Strategy for Failed Transvenous Left-Ventricular Lead Placement in Cardiac Resynchronization Therapy: Surrender or Struggle?

INTRODUCTION: For those cardiac resynchronization therapy (CRT) candidates who experience left-ventricular (LV) lead placement failure or underwent concomitant cardiac surgeries, surgical placement of epicardial LV lead guided by electroanatomic mapping may be a promising alternative. METHODS: Electroanatomic mapping was used to guide positioning of the LV lead through a surgical approach. The LV lead was placed at the region with the latest local LV activation and normal voltage, away from the scar. RESULTS: From April 2010 to September 2018, 10 consecutive patients (3 female) underwent surgical epicardial LV lead implantation. Among them, 3 had other surgical indications simultaneously (including 1 CRT non-responder), and 7 had failed transvenous LV lead placement. After CRT, the QRS duration was shortened from 149.3 ± 20.4 ms to 125.1 ± 15.2 ms (p = 0.01). At 6 months, the LV ejection fraction was significantly improved and remained stable in the follow-up (FU) period thereafter (baseline vs. 6 months, 31.0 ± 8.3% vs. 42.2 ± 13.4%, p = 0.006). Other parameters, including the threshold and impedance of the LV lead, were also stable at a mean FU of 755 ± 406 days, and the NYHA functional classification decreased from 2.9 ± 0.7 to 1.8 ± 0.8 (p = 0.002). CONCLUSIONS: Placement of an epicardial LV lead guided by electroanatomic mapping could be used as an adjunctive strategy in patients who were unable or refractory to conventional CRT therapy. This approach could also be applied in patients who had other surgical indications at the same time.

Catheter ablation of ventricular tachycardia in patients with postinfarction left ventricular aneurysm.

BACKGROUND: While ventricular tachycardia (VT) in the setting of postmyocardial infarction left ventricular aneurysms (LVA) is not uncommonly encountered, there is a scarcity of data regarding the safety, efficacy, and outcomes of ablation of VT in this subset of patients. METHODS: Our study included consecutive patients aged 18 years or older with postmyocardial infarction LVA who presented to Mayo Clinic for catheter ablation of VT between 2002 and 2018. RESULTS: Of 34 patients, the mean age was 70.4 ± 9.1 years; 91% were male. Mean LVEF was 29 ± 9.7% and left ventricular end-diastolic dimension was 64.9 ± 6.6 mm. The site of the LVA was apical in 21 patients (62%). Fifteen patients (44%) presented with electrical storm or incessant VT. Nine patients (26%) had a history of intracardiac thrombus. All except for one patient had at least one VT originating from the aneurysm. The mean number of VTs was 2.9 ± 1.7. All patients underwent ablation at the site of the aneurysm. Ablation outside the aneurysm was performed in 13 patients (38%). Low-voltage fractionated potentials and/or late potentials at the aneurysmal site were present in all cases. Complete elimination of all VTs was achieved in 18 (53%), while the elimination of the clinical VT with continued inducibility of nonclinical VTs was achieved in a further 11 patients (32%). Two patients developed cardiac tamponade requiring pericardiocentesis. During a mean follow-up period of 2.3 ± 2.4 years, 11 patients (32%) experienced VT recurrence. Freedom from all-cause mortality at 1-year follow-up was 94%. CONCLUSION: Radiofrequency catheter ablation targeting the aneurysmal site is a feasible and reasonably effective management strategy for clinical VTs in patients with postinfarction LVA.

Using ensemble of ensemble machine learning methods to predict outcomes of cardiac resynchronization.

INTRODUCTION: The efficacy of cardiac resynchronization therapy (CRT) has been widely studied in the medical literature; however, about 30% of candidates fail to respond to this treatment strategy. Smart computational approaches based on clinical data can help expose hidden patterns useful for identifying CRT responders. METHODS: We retrospectively analyzed the electronic health records of 1664 patients who underwent CRT procedures from January 1, 2002 to December 31, 2017. An ensemble of ensemble (EoE) machine learning (ML) system composed of a supervised and an unsupervised ML layers was developed to generate a prediction model for CRT response. RESULTS: We compared the performance of EoE against traditional ML methods and the state-of-the-art convolutional neural network (CNN) model trained on raw electrocardiographic (ECG) waveforms. We observed that the models exhibited improvement in performance as more features were incrementally used for training. Using the most comprehensive set of predictors, the performance of the EoE model in terms of the area under the receiver operating characteristic curve and F1-score were 0.76 and 0.73, respectively. Direct application of the CNN model on the raw ECG waveforms did not generate promising results. CONCLUSION: The proposed CRT risk calculator effectively discriminates which heart failure (HF) patient is likely to respond to CRT significantly better than using clinical guidelines and traditional ML methods, thus suggesting that the tool can enhanced care management of HF patients by helping to identify high-risk patients.

Catheter ablation of premature ventricular contractions originating from periprosthetic aortic valve regions.

BACKGROUND: Little is known about the ablation outcomes of premature ventricular contractions (PVCs) that originate from the periprosthetic aortic valve (PPAV) regions of patients with aortic valve replacement (AVR). METHODS AND RESULTS: Our study had 11 patients who underwent catheter ablation for PVCs arising from the PPAV regions (bioprosthetic aortic valve, n = 5; mechanical aortic valve, n = 6). The PVC characteristics, procedure characteristics, and efficacy of ablation were compared with the control group (n = 33). At baseline, the PPAV group had a lower left ventricular ejection fraction (mean [SD], 41% [12%] vs. 51% [8%]; p = .002). The rate of acute ablation success was 90.9% in the PPAV group. Ablation sites were identified above the left coronary cusp (LCC) and right coronary cusp commissure (LRCC) in one PVC, below the prosthetic valve in eight PVCs (four below LCC and four below LRCC), and within the distal coronary sinus in two PVCs. The mean procedure time, fluoroscopy time, and radiation in the PPAV group were all significantly greater than those in the control group (all p < .05). However, the number of radiofrequency ablation energy deliveries was not different. The PPAV group had a long-term success rate compared with the control group (72.7% vs. 87.9%, p = .48) and an increase of left ventricular ejection fraction from 43% to 49% after successful PVC ablation at follow-up (p < .001). Echocardiography showed no significant change in valve regurgitation after ablation. No new atrioventricular block occurred. CONCLUSION: PVCs arising from PPAV regions can be successfully ablated in patients with prior AVR, without damaging the prosthetic aortic valve and atrioventricular conduction.