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We review the pharmacologic, interventional and device programming treatment options for patients with implantable cardioverter-defibrillators who present with acute heart failure and implantable cardioverter-defibrillator shocks. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this study was to compare the characteristics and prevalence of late potentials (LP) in patients with nonischemic cardiomyopathy (NICM) and ischemic cardiomyopathy (ICM) etiologies and evaluate their value as targets for catheter ablation.Background: LP are frequently found in post-myocardial infarction scars and are useful ablation targets. The relative prevalence and characteristics of LP in patients with NICM is not well understood.Methods: Thirty-three patients with structural heart disease (NICM, n = 16; ICM, n = 17) referred for catheter ablation of ventricular tachycardia were studied. Electroanatomic mapping was performed endocardially (n = 33) and epicardially (n = 19). The LP were defined as low voltage electrograms (<1.5 mV) with onset after the QRS interval. Very late potentials (vLP) were defined as electrograms with onset >100 ms after the QRS.Results: We sampled an average of 564 +/- 449 points and 726 +/- 483 points in the left ventricle endocardium and epicardium, respectively. Mean total low voltage area in patients with ICM was 101 +/- 55 cm(2) and 56 +/- 33 cm(2), endocardial and epicardial, respectively, compared with NICM of 55 +/- 41 cm(2) and 53 +/- 28 cm(2), respectively. Within the total low voltage area, vLP were observed more frequently in ICM than in NICM in endocardium (4.1% vs. 1.3%; p = 0.0003) and epicardium (4.3% vs. 2.1%, p = 0.035). An LP-targeted ablation strategy was effective in ICM patients (82% nonrecurrence at 12 +/- 10 months of follow-up), whereas NICM patients had less favorable outcomes (50% at 15 +/- 13 months of follow-up).Conclusions: The contribution of scar to the electrophysiological abnormalities targeted for ablation of unstable ventricular tachycardia differs between ICM and NICM. An approach incorporating LP ablation and pace-mapping had limited success in patients with NICM compared with ICM, and alternative ablation strategies should be considered. [ABSTRACT FROM AUTHOR]

Background: Recurrent ventricular tachycardia (VT) after prior endocardial catheter ablation(s) presents challenges in the setting of prior cardiac surgery where percutaneous epicardial access may not be feasible., Objective: The purpose of this study was to compare the outcomes of cryothermal vs radiofrequency ablation in direct surgical epicardial access procedures., Methods: We performed a retrospective study of consecutive surgical epicardial VT ablation cases. Surgical cases using cryothermal vs radiofrequency ablation were analyzed and outcomes were compared., Results: Between 2009 and 2022, 43 patients underwent either a cryothermal (n = 17) or a radiofrequency (n = 26) hybrid epicardial ablation procedure with direct surgical access. Both groups were similarly matched for age, sex, etiology of VT, and comorbidities with a high burden of refractory VT despite previous endocardial and/or percutaneous epicardial ablation procedures. The surgical access site was lateral thoracotomy (76.5%) in the cryothermal ablation group compared with lateral thoracotomy (42.3%) and subxiphoid approach (38.5%) in the radiofrequency group, with the remainder in both groups performed via median sternotomy. The ablation time was significantly shorter in those undergoing cryothermal ablation vs radiofrequency ablation (11.54 ± 15.5 minutes vs 48.48 ± 23.6 minutes; P < .001). There were no complications in the cryothermal ablation group compared with 6 patients with complications in the radiofrequency group. Recurrent VT episodes and all-cause mortality were similar in both groups., Conclusion: Hybrid surgical VT ablation with cryothermal or radiofrequency energy demonstrated similar efficacy outcomes. Cryothermal ablation was more efficient and safer than radiofrequency in a surgical setting and should be considered when surgical access is required., (Copyright © 2023 Heart Rhythm Society. All rights reserved.)

Sudden cardiac arrest (SCA) is the leading cause of death in young athletes. Despite efforts to improve preparedness for cardiac emergencies, the incidence of out-of-hospital cardiac arrests in athletes remains high, and bystander awareness and readiness for SCA support are inadequate. Initiatives such as designing an emergency action plan (EAP) and mandating training in cardiopulmonary resuscitation (CPR) and automated external defibrillator use (AED) for team members and personnel can contribute to improved survival rates in SCA cases. This review provides an overview of SCA in athletes, focusing on identifying populations at the highest risk and evaluating the effectiveness of different screening practices in detecting conditions that may lead to SCA. We summarize current practices and recommendations for improving the response to SCA events, and we highlight the need for ongoing efforts to optimize preparedness through the implementation of EAPs and the training of individuals in CPR and AED use. Additionally, we propose a call to action to increase awareness and training in EAP development, CPR, and AED use for team members and personnel. To improve outcomes of SCA cases in athletes, it is crucial to enhance bystander awareness and preparedness for cardiac emergencies. Implementing EAPs and providing training in CPR and AED use for team members and personnel are essential steps toward improving survival rates in SCA cases., (© 2023 The Authors. Clinical Cardiology published by Wiley Periodicals, LLC.)

Background: The clinical relevance and prognostic implications of ventricular parasystole are unknown., Objectives: This study sought to assess the prevalence of ventricular parasystole in patients with implantable cardioverter-defibrillators (ICDs) and ventricular parasystole's association with ventricular arrhythmias and conduction system abnormalities., Methods: This study retrospectively evaluated patients who underwent ICD interrogation at a single center between June 1, 2019, and August 31, 2020, and reviewed all available ICD and electrocardiogram data. This study identified patients with ventricular parasystole and compared the prevalence of ventricular fibrillation (VF), ventricular tachycardia (VT), and new conduction system abnormalities in those with ≥5 years of intrinsic QRS-complex electrocardiograms to those without parasystole., Results: This study included 374 patients (age 57 ± 21 years, 72% male, 45% nonischemic, 32% ischemic cardiomyopathy), of which, 104 (28%) had VT only, 39 (10%) VF only, and 10 (3%) both VT/VF. Ventricular parasystole was identified in 33 patients (9%); parasystolic foci were predominantly from the His-Purkinje system. Compared with those without parasystole, patients with parasystole had a significantly higher rate of VF (36% vs 11%; P < 0.01), but not VT (42% vs 29%; P = 0.12). Patients with parasystole, compared with those without parasystole, had a higher prevalence of new conduction abnormalities, particularly progressive intraventricular conduction delay (11 of 18 [61%] vs 12 of 83 [14%]; P < 0.01) and new right bundle branch block (4 of 18 [22%] vs 1 of 83 [1%]; P < 0.01)., Conclusions: Ventricular parasystole was strongly associated with new conduction system abnormalities and VF in patients who have cardiomyopathy with ICDs, suggesting a potential link between VF and His-Purkinje damage in this patient population., Competing Interests: Funding Support and Author Disclosures Dr Bradfield and Dr Shivkumar are supported by National Institutes of Health grant OT2OD028201. Dr Do has received research funding and speaker fees from Medtronic Inc. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: The use of left bundle branch pacing (LBBP) has dramatically increased since it was first described in 2016, but to date there are no published data on the safety of performing magnetic resonance imaging (MRI) in these patients., Methods: Patients with LBBP who underwent MRI between January 2016 and October 2022 were retrospectively studied in our clinical center, which has a special program for imaging patients with cardiac devices. All patients underwent close cardiac monitoring throughout the MRI scans. Occurrence of arrhythmias or other adverse effects during MRI were assessed. LBBP lead parameters immediately pre- and post-MRI and at an outpatient follow-up were compared., Results: Fifteen patients with LBBP underwent a total of 19 MRI sessions during the study period. Lead parameters did not significantly change after the MRI or on follow-up, which took place at a median of 91 days after the MRI. No patient developed arrhythmias during the MRI sessions, and no adverse effects such as lead dislodgement were reported., Conclusion: Although larger studies are necessary to verify our findings, MRI in patients with LBBP appears safe based on this initial case series., (© 2023 Wiley Periodicals LLC.)

Background: Bradyarrhythmias including sinus node dysfunction (SND) and atrioventricular block (AVB) can necessitate pacemaker (PPM) implantation in orthotopic heart transplant (OHT) recipients. Prior studies have shown conflicting findings regarding the effect of PPM implantation on survival. We evaluated the effect of PPM indication on long-term re-transplant-free survival in OHT patients., Methods: We conducted a retrospective cohort study of OHT patients at UCLA Medical Center from 1985 to 2018. Indication for PPM (SND, AVB) was identified. Cox proportional hazards model with pacemaker implantation as a time-varying covariate was used to evaluate its effect on the primary endpoint of retransplant or death. We included 1609 OHTs in 1511 adult patients with median follow-up of 12 years., Results: At transplant, patients were aged 53 ± 13 years and 1125 (74.5%) were male. Pacemakers were implanted in 109 (7.2%) patients; 65 for SND (4.3%) and 43 for AVB (2.8%). Repeat OHT was performed in 103 (6.4%) cases and 798 (52.8%) patients died during the follow-up period. The risk of the primary endpoint was significantly higher in patients requiring PPM for AVB (HR 3.0, 95% CI 2.1-4.2, p < .01) after controlling for age at OHT, gender, hypertension, diabetes, renal disease, history of repeat OHT, acute rejection, transplant coronary vasculopathy, and atrial fibrillation, but not PPM for SND (HR 1.0, 95% CI 0.70-1.4, p = 1.0)., Conclusions: Patients who required PPM for AVB, but not SND, were at significantly higher risk of death or retransplant compared to patients who did not require PPM., (© 2023 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals LLC.)

We describe the case of a 92-year-old male patient presenting with shortness of breath and an electrocardiogram showing bradycardia with irregular rhythm and varying QRS morphology. A differential diagnosis is discussed. ( Level of Difficulty: Advanced. )., Competing Interests: Dr Do has received research funding and speaker fees from Medtronic, Inc. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (© 2023 The Authors.)

Introduction: Respiratory failure is a common cause of pulseless electrical activity (PEA) and asystolic cardiac arrest, but the changes in heart rate (HR) pre-arrest are not well described. We describe HR dynamics prior to in-hospital cardiac arrest (IHCA) among PEA/asystole arrest patients with respiratory etiology., Methods: In this retrospective study, we evaluated 139 patients with 3-24 hours of continuous electrocardiogram data recorded preceding PEA/asystole IHCA from 2010-2017. We identified respiratory failure cases by chart review and evaluated electrocardiogram data to identify patterns of HR changes, sinus bradycardia or sinus arrest, escape rhythms, and development right ventricular strain prior to IHCA., Results: A higher proportion of respiratory cases (58/73, 79 %) fit a model of HR response characterized by tachycardia followed by rapid HR decrease prior to arrest, compared to non-respiratory cases (30/66, 45 %, p < 0.001). Among the 58 respiratory cases fitting this model, 36 (62 %) had abrupt increase in HR occurring 64 (IQR 23-191) minutes prior to arrest, while 22 (38 %) had stable tachycardia until time of HR decrease. Mean peak HR was 123 ± 21 bpm. HR decrease occurred 3.0 (IQR 2.0-7.0) minutes prior to arrest. Sinus arrest occurred during the bradycardic phase in 42/58 of cases; escape rhythms were present in all but 2/42 (5 %) cases. Right ventricular strain ECG pattern, when present, occurred at a median of 2.2 (IQR -0.05-17) minutes prior to onset of HR decrease., Conclusion: IHCAs of respiratory etiology follow a model of HR increase from physiologic compensation to hypoxia, followed by rapid HR decrease prior to arrest., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: XH is an inventor of US Patent 9,936,923 and 9,600,990, assigned to the University of California, Los Angeles. Other authors have no conflicts of interest to disclose., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

Cardiac implantable electronic devices (CIEDs) store information continuously; however, the log of these devices is rarely analyzed in forensic practice. We retrospectively reviewed all cases referred for CIED interrogation by the Los Angeles County Department of Medical Examiner-Coroner between 2001 and 2020. According to the Department's practice, CIED interrogation may be requested for decedents in which details or cause of death are not clear from autopsy and clinical history. The CIED analysis was considered informative for the coroner's investigation either if it detected an arrhythmia or malfunction likely related to decedent's terminal event or if it was essential to determine time of death or identity of decedent. A total of 57 CIEDs were evaluated during the 20-year period. In almost half of cases (26/57: 45.6%), device analysis was informative for coroner's investigation. Arrhythmias likely related to terminal event were commonly detected (21/57: 36.8%). Device malfunction was identified as the likely cause of death in almost 10% of decedents (5/57: 8.8%), including three cases of battery depletion (3/57: 5.3%), one case of misclassification of ventricular tachycardia as supraventricular tachycardia with failure to deliver therapy (1/57: 1.7%), and one case of lead failure due to a broken pacing wire (1/57: 1.7%). Not infrequently, CIED interrogation was essential for determination of time of death (9/57: 15.8%), and there was one case (1/57: 1.7%) in which interrogation was essential for identifying the decedent. Our study shows that postmortem CIED interrogation can provide unique information regarding mechanism and time of death, and decedent's identity., (© 2022 American Academy of Forensic Sciences.)

Atrial fibrillation (AF) is the most common cardiac arrhythmia and its prevalence is continuously increasing in the United States, leading to a progressive rise in the number of disease-related emergency department (ED) visits and hospitalizations. Although optimal long-term outpatient management for AF is well defined, the guidelines for optimal ED management of acute AF episodes is less clear. Studies have demonstrated that discharging patients with AF from the ED after acute stabilization is both safe and cost effective; however, the majority of these patients in the United States and in our institution are admitted to the hospital. To improve care of these patients, we established a multidisciplinary collaboration to develop an evidence-based systematic approach for the treatment and management of AF in the ED, that led to the creation of the University of California-Cardioversion, Anticoagulation, Rate Control, Expedited Follow-up/Education Atrial Fibrillation Pathway. Our pathway focuses on the acute stabilization of AF, adherence to best practices for anticoagulation, and reduction in unnecessary admissions through discharge from the ED with expedited outpatient follow-up whenever safe. A novel aspect of our pathway is that it is primarily driven by the ED physicians, while other published protocols primarily involve consulting cardiologists to guide management in the ED. Our protocol is very pertinent considering the current trend toward increased AF prevalence in the United States, coupled with a need for widespread implementation of strategies aimed at improving management of these patients while safely reducing hospital admissions and the economic burden of AF., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Initial studies have reported excellent safety and efficacy for stereotactic body radiation therapy (SBRT) in patients with refractory ventricular tachycardia (VT)., Methods: This is a single-center retrospective analysis of eight consecutive patients who underwent SBRT for refractory, scar-related VT. The anatomic target for radioablation was defined based on surface 12-lead ECG VT morphology, cardiac magnetic resonance imaging, and electroanatomic mapping data when available. The target volume treated and the prescribed radiation dose (15-25 Gy) was based on the combined clinical assessment of the cardiac electrophysiologist and radiation oncologist. Ventricular arrhythmias, radiation-related outcomes, and adverse events were monitored at follow-up., Results: Eight patients underwent nine SBRT sessions. All patients were male with an average age of 75 ± 7.3 years and mean ejection fraction of 21 ± 7%. SBRT was performed with delivery of an average of 22.2 ± 3.6 Gy in a single session with a procedure time of 18.2 ± 6.0 min. All but one session was performed on an inpatient basis. No acute complications occurred. During a median follow-up of 7.8 months (IQR 4.8, 9.9), ICD therapies decreased from median 69.5 (43.5, 115.8) pre-SBRT to 13.3 (IQR 7.7, 35.8) post-SBRT (p = 0.036). There were three patient deaths in the follow-up period, unrelated to SBRT. Apparent clinical benefit occurred 33% of the time after SBRT., Conclusions: The patients experienced overall reduction in VT burden following SBRT, though not with the immediate effect seen in other patient series. Further studies (basic, translational, and clinical) are essential to determine the benefit of SBRT and if so, the optimal protocols and patient selection., (© 2020. Springer Science+Business Media, LLC, part of Springer Nature.)

Background Cardiac sympathetic denervation (CSD) has been used as a bailout strategy for refractory ventricular tachycardia (VT). Risk of VT recurrence in patients with scar-related monomorphic VT referred for CSD and the extent to which CSD can modify this risk is unknown. We aimed to quantify arrhythmia recurrence risk and impact of CSD in this population. Methods and Results Adjusted competing risk time to event models were developed to adjust for risk of VT recurrence and sustained VT/implantable cardioverter-defibrillator shocks after VT ablation based on patient comorbidities at the time of VT ablation. Adjusted VT and implantable cardioverter-defibrillator shock recurrence rates were estimated for the subgroup who subsequently required CSD after ablation. The expected adjusted recurrence rates were then compared with the observed rates after CSD. Data from 381 patients with scar-mediated monomorphic VT who underwent VT ablation were analyzed, excluding patients with polymorphic VT. Sixty eight patients underwent CSD for recurrent VT. CSD reduced the expected adjusted VT recurrence rate by 36% (expected rate of 5.61 versus observed rate of 3.58 per 100 person-months, P =0.01) and the sustained VT/implantable cardioverter-defibrillator shock rates by 34% (expected rate of 4.34 versus observed 2.85 per 100 person-months, P =0.03). The median number of sustained VT/implantable cardioverter-defibrillator shocks in the year before versus the year after CSD was reduced by 90% (10 versus 1, P <0.0001). Conclusions Patients referred for CSD for refractory scar-mediated monomorphic VT are at a higher risk of VT recurrence after ablation as compared with those not requiring CSD, mostly because of their cardiac comorbidities. CSD significantly reduced both the expected risk of recurrences and VT burden.

Hybrid surgical ventricular tachycardia (VT) ablation combines surgical epicardial access/exposure with contemporary mapping and ablation techniques adapted from percutaneous catheter ablation procedures. Patients considered for a hybrid surgical approach for VT are those who have had prior cardiac surgery or failed percutaneous epicardial access due to pericardial adhesions. They often represent the most challenging end of the spectrum of patients and usually have undergone multiple unsuccessful ablations. In this review, the indications, preprocedure work-up, ablation techniques, and outcomes from hybrid surgical access VT ablations are discussed as well as key technical details that present unique challenges to its success., Competing Interests: Disclosure The authors have no conflicts of interest to disclose., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Introduction: Cardiac sympathetic denervation (CSD) is utilized for the management of ventricular tachycardia (VT) in structural heart disease when refractory to radiofrequency ablation (RFA) or when patient/VT characteristics are not conducive to RFA., Methods: We studied consecutive patients who underwent CSD at our institution from 2009 to 2018 with VT requiring repeat RFA post-CSD. Patient demographics, VT/procedural characteristics, and outcomes were assessed., Results: Ninety-six patients had CSD, 16 patients underwent RFA for VT post-CSD. There were 15 male and 1 female patients with mean age of 54.2 ± 13.2 years. Fourteen patients had nonischemic cardiomyopathy. A mean of 2.0 ± 0.8 RFAs for VT was unsuccessful before the patient undergoing CSD. The median time between CSD and RFA was 104 days (interquartile range [IQR] = 15-241). The clinical VT cycle length was significantly increased after CSD both spontaneously on ECG and/or ICD interrogation (355 ± 73 ms pre-CSD vs. 422 ± 94 ms post-CSD, p = .001) and intraprocedurally (406 ± 86 ms pre-CSD vs. 457 ± 88 ms post-CSD, p = .03). Two patients had polymorphic and 14 had monomorphic VT (MMVT) pre-CSD, and all patients had MMVT post-CSD. The proportion of mappable, hemodynamically stable VTs increased from 35% during pre-CSD RFA to 58% during post-CSD RFA (p = .038). At median follow-up of 413 days (IQR = 43-1840) after RFA, eight patients had no further VT., Conclusion: RFA for recurrent MMVT post-CSD is a reasonable treatment option with intermediate-term clinical success in 50% of patients. Clinical VT cycle length was significantly increased after CSD with associated improvement in mappable, hemodynamically tolerated VT during RFA., (© 2020 Wiley Periodicals LLC.)

Aim: The role of the right ventricle (RV) in pulseless electrical activity (PEA) is poorly defined outside of pulmonary embolism. We aimed to (1) describe the continuous electrocardiographic (ECG) manifestations of RV strain (RVS) preceding PEA/Asystole in-hospital cardiac arrest (IHCA), and (2) determine the prevalence and clinical causes of RVS in PEA/Asystole IHCA., Methods: In this retrospective cross-sectional study, we evaluated 140 patients with continuous ECG data preceding PEA/Asystole IHCA. We iteratively defined the RVS continuous ECG pattern using the development cohort (93 patients). Clinical cause determination was blinded from ECG analysis in the validation cohort (47 patients)., Results: The overall cohort had mean age 62.1 ± 17.1 years, 70% return of spontaneous circulation and 30% survival to discharge. RVS continuous ECG pattern was defined as progressive RV depolarization delay in lead V1 with at least one supporting finding of RV ischaemia or right axis deviation. Using this criterion, 66/140 (47%) cases showed preceding RVS. In patients with RVS, no pulmonary embolism was found in 9/13 (69%) autopsies and 8/10 (80%) CT chest angiograms. The positive and negative predictive value of RVS pattern for diagnosing a respiratory cause of PEA/Asystole in the validation cohort was 81% [95% CI 64-98%] and 58% [95% CI 36-81%], respectively., Conclusion: RVS continuous ECG pattern preceded 47% of PEA/Asystole IHCA and is predictive of a respiratory cause of cardiac arrest, not just pulmonary embolism. These suggest that rapid elevations in pulmonary pressures and resultant RV failure may cause PEA in respiratory failure., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Autonomic modulation is finding an increasing role in the treatment of ventricular arrhythmias. Renal denervation (RDN) has been described as a treatment modality for refractory ventricular tachycardia (VT) in case series., Objective: The purpose of this study was to evaluate RDN as an adjunctive therapy to cardiac sympathetic denervation (CSD) for ablation refractory VT., Methods: Patients who underwent RDN after radiofrequency ablation and CSD procedures at our center from 2012 to 2019 were evaluated., Results: Ten patients underwent RDN after CSD (9 bilateral and 1 left-sided only) with a median follow-up of 23 months. The mean age was 59.9 ± 10.4 years, and 9/10 (90%) were men. All had cardiomyopathy with a mean ejection fraction of 33% ± 11% (20% ischemic). Four (40%) underwent CSD during the same hospitalization as that for RDN. Patients who underwent RDN as adjunctive therapy to CSD had a decrease in all implantable cardioverter-defibrillator therapies (shocks + antitachycardia pacing [ATP]) from 29.5 ± 25.2 to 7.1 ± 10.1 comparing 6 months pre-RDN to 6 months post-RDN (P = .028). Implantable cardioverter-defibrillator shocks were significantly decreased from 7.0 ± 6.1 to 1.7 ± 2.5 comparing 6 months pre-RDN to 6 months post-RDN (P = .026). This benefit was driven by a decrease in therapies for 6 patients who had a staged procedure, not performed during the same hospitalization (28.5 ± 24.3 to 1.0 ± 1.2; P = .043)., Conclusion: RDN demonstrates the potential benefit when VT recurs after radiofrequency ablation and CSD. The benefit is seen in patients who undergo a staged procedure. The need for acute RDN after CSD portends a poor prognosis., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Survival from in-hospital cardiac arrest (IHCA) due to pulseless electrical activity/asystole remains poor. We aimed to evaluate whether electrocardiographic changes provide predictive information for risk of IHCA from pulseless electrical activity/asystole. We conducted a retrospective case-control study, utilizing continuous electrocardiographic data from case and control patients. We selected 3 consecutive 3-hour blocks (block 3, 2, and 1 in that order); block 1 immediately preceded cardiac arrest in cases, whereas block 1 was chosen at random in controls. In each block, we measured dominant positive and negative trends in electrocardiographic parameters, evaluated for arrhythmias, and compared these between consecutive blocks. We created random forest and logistic regression models, and tested them on differentiating case versus control patients (case block 1 vs control block 1), and temporal relation to cardiac arrest (case block 2 vs case block 1). Ninety-one cases (age 63.0 ± 17.6, 58% male) and 1,783 control patients (age 63.5 ± 14.8, 67% male) were evaluated. We found significant differences in electrocardiographic trends between case and control block 1, particularly in QRS duration, QTc, RR, and ST. New episodes of atrial fibrillation and bradyarrhythmias were more common before IHCA. The optimal model was the random forest, achieving an area under the curve of 0.829, 63.2% sensitivity, 94.6% specificity at differentiating case versus control block 1 on a validation set, and area under the curve 0.954, 91.2% sensitivity, 83.5% specificity at differentiating case block 1 versus case block 2. In conclusion, trends in electrocardiographic parameters during the 3-hour window immediately preceding IHCA differ significantly from other time periods, and provide robust predictive information., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Purpose: Fluoroscopically guided interventional (FGI) procedures often have lower complication rates compared with alternative surgical procedures, providing an option for patients with a high risk of perioperative mortality. Although severe radiation injuries are rare, patients receiving peak skin doses exceeding 3 Gy can suffer from radiation-induced tissue injuries, ranging from transient erythema to nonhealing wounds. As these iatrogenic injuries may manifest weeks to months postprocedure, proper diagnosis and timely medical intervention are less likely. Clinically, the lack of situational awareness for monitoring air kerma continues to be a challenge despite the recommendations of numerous organizations on ways to achieve fluoroscopy safety. For patient safety efforts, this study aimed to identify and mitigate systematic gaps associated with potentially high-radiation dose fluoroscopic procedures in US Department of Veterans Affairs (VA) and non-VA medical institutions., Methods: In this study, a multi-institutional team utilized Healthcare Failure Mode and Effect Analysis (HFMEA) on an example implantable cardioverter defibrillator lead extraction procedure., Results: With this approach, 29 interventions were devised and prioritized by feasibility, cost-effectiveness, and expected clinical impact. Five of the 29 interventions were recommended for immediate implementation or piloting., Conclusions: This work demonstrates the application of formal risk-based analysis techniques in FGI procedures. These high priority interventions may be valuable for other facilities to consider when performing potentially high-radiation dose procedures and conducting risk-benefit analyses. Formal risk analysis techniques such as the HFMEA process are recommended for other facilities to use to improve safety for their high-risk procedures., (Copyright © 2019 American College of Radiology. All rights reserved.)

Introduction: Frequent premature ventricular complexes (PVCs) can lead to symptoms, such as cardiomyopathy and increased mortality. Beta-blockers are recommended as first-line therapy to reduce PVC burden; however, the response is unpredictable. The objective of this study is to determine whether PVC diurnal-variability patterns are associated with different clinical profiles and predict drug response., Methods: Consecutive patients with frequent PVCs (burden ≥ 1%), referred for Holter monitoring between 2014 and 2016, were included. Follow-up Holters, when available, were assessed after beta-blocker initiation to assess response (≥50% reduction). Patients were divided into three groups on the basis of relationship between hourly PVC count and mean HR during each of the 24 Holter hours: (1) fast-HR-dependent-PVC (F-HR-PVC) for positive correlation (Pearson, P < 0.05), (2) slow-HR-dependent-PVC (S-HR-PVC) for a negative, and (3) independent-HR-PVC (I-HR-PVC) when no correlation was found., Results: Of the 416 patients included, 50.2% had F-HR-PVC, 35.6% I-HR-PVC, and 14.2% S-HR-PVC with distinct clinical profiles. Beta-blocker therapy was successful in 34.0% patients overall: patients with F-HR-PVC had a decrease in PVC burden (18.8 ± 10.4% to 9.3 ± 6.6%, P < 0.0001; 62% success), I-HR-PVC had no change (18.4 ± 17.9% to 20.6 ± 17.9%, P = 0.175; 0% success), whereas S-HR-PVC had an increase in burden (14.6 ± 15.3% to 20.8 ± 13.8%, P = 0.016; 0% success). The correlation coefficient was the only predictor of beta-blocker success (AUC = 0.84, sensitivity = 100%, specificity = 67.7%; r ≥ 0.4)., Conclusions: A simple analysis of Holter PVC diurnal variability may provide incremental value to guide clinical PVC management. Only patients displaying a F-HR-PVC profile benefited from beta-blockers. An alternative strategy should be considered for others, as beta-blockers may have no effect or can even be harmful., (© 2019 Wiley Periodicals, Inc.)

Ventricular arrhythmias are challenging to manage in athletes with concern for an elevated risk of sudden cardiac death (SCD) during sports competition. Monomorphic ventricular arrhythmias (MMVA), while often benign in athletes with a structurally normal heart, are also associated with a unique subset of idiopathic and malignant substrates that must be clearly defined. A comprehensive evaluation for structural and/or electrical heart disease is required in order to exclude cardiac conditions that increase risk of SCD with exercise, such as hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. Unique issues for physicians who manage this population include navigating athletes through the decision of whether they can safely continue their chosen sport. In the absence of structural heart disease, therapies such as radiofrequency catheter ablation are very effective for certain arrhythmias and may allow for return to competitive sports participation. In this comprehensive review, we summarise the recommendations for evaluating and managing athletes with MMVA., Competing Interests: Disclosure: JB has previously received honoraria from Abbott Medical and Biosense Webster. The other authors have no conflicts of interest to declare related to the topics discussed in this manuscript.

When the transvenous ICD initially came into use for primary and secondary prevention of sudden cardiac death, defibrillation threshold (DFT) testing was universally performed. However, DFT testing is no longer routinely recommended for transvenous ICD implantation except in certain situations. Risk scores can help guide the decision to perform DFT testing. The subcutaneous ICD represents an area of uncertainty, with limited data available regarding the role of DFT testing in these devices. Current guidelines give a class I recommendation for performing DFT testing at the time of implant. Further studies are needed before this recommendation can be safely dismissed., Competing Interests: Disclosure: The authors have no conflicts of interest to declare.

The role of the anesthesiologist in lead extraction procedures is multifaceted and highlights the collaborative, multidisciplinary teamwork needed to ensure patient safety and procedural success in these complex cases. Thorough preoperative evaluation and identification of high-risk characteristics enable the anesthesiologist to tailor a comprehensive intraoperative and postoperative care plan for each case. Institutional practices may vary but anesthetic management typically includes general anesthesia with an endotracheal tube, invasive measurement of arterial blood pressure, vascular access for rapid volume expansion, echocardiographic monitoring, preparation for blood transfusion, and initiation of cardiopulmonary bypass in the event of an emergency., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Lead management describes a comprehensive approach to cardiac implantable electronic device lead utilization, encompassing lead and device selection, vascular access, implant techniques, handling lead failures and recalls, managing infectious and other complications, and performing device and lead extraction. Device and lead selection should be based on the latest guidelines and the available data to choose the optimal device system for each patient. Lead extraction is a highly specialized procedure and should be carried out by a team of personnel extensively trained in the procedure at centers with cardiac surgical support., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Ventricular tachycardia is a common arrhythmia in patients with structural heart disease and heart failure, and is now seen more frequently as these patients survive longer with modern therapies. In addition, these patients often have multiple comorbidities. While anti-arrhythmic drug therapy, implantable cardioverter-defibrillator implantation and ventricular tachycardia ablation are the mainstay of therapy, well managed by the cardiac electrophysiologist, there are many other facets in the care of these patients, such as heart failure management, treatment of comorbidities and anaesthetic interventions, where the expertise of other specialists is essential for optimal patient care. A coordinated team approach is therefore essential to achieve the best possible outcomes for these complex patients., Competing Interests: Disclosure: The authors have no conflict of interest to declare.

Transvenous approaches for pacemaker and defibrillator lead insertion offer numerous advantages over epicardial techniques. Although the cephalic, axillary, and subclavian veins are most commonly used in clinical practice, they each offer their own set of advantages and disadvantages that leave their usage dependent on patient anatomy and physician preference. Alternative methods using the upper and lower venous circulation have been described when these veins are not available or practical for lead insertion. Until current technology is superseded by leadless pacing systems, the search for the optimal lead insertion technique continues., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The purpose of this study was to explore the usability of the cephalic vein (CV) for cardiac implantable electronic device (CIED) lead access by applying a scoring system to assess the venous anatomy. This prospective, single-center study included 100 consecutive patients who underwent CIED implantation within a period of one year. Contrast-enhanced venography images were obtained for every patient, focused on the CV, "T-junction," and the subclavian/axillary veins (SV/AVs). Though careful examination of the images, an angle, valves, diameter, noncollateral (AVDnC) score was constructed and used to aid in choosing a CV or SV/AV access approach; in all cases, however, the preferred approach was CV independent of the AVDnC score result obtained. Upon use of the scoring system, the majority of patients (54%) had type A score result (≥ 3), indicating a favorable anatomy for CV access. In 48 of these patients, the CV was used for the implantation of at least one lead. The remaining 46 (46%) patients had type B score result (≤ 2). In 41 patients from this group, SV/AV access was used for lead implantation and, in five patients, CV access was used. The number of leads introduced through the CV was associated with larger score and the operator's experience. In conclusion, in more than 50% of patients, at least one lead could be introduced through the CV. The scoring system used herein can simplify the choice between CV and SV/AV access and could eventually increase the efficiency and safety of the procedure, especially when less experienced implanters are involved., Competing Interests: The authors report no conflicts of interest for the published content., (Copyright: © 2018 Innovations in Cardiac Rhythm Management.)

Bedside monitors in hospital intensive care units (ICUs) are known to produce excessive false alarms that could desensitize caregivers, resulting in delayed or even missed clinical interventions to life-threatening events. Our previous studies proposed a framework aggregating information in monitor alarm data by mining frequent alarm combinations (i.e., SuperAlarm) that are predictive to clinical endpoints, such as code blue events, in an effort to address this critical issue. In the present pilot study, we hypothesize that sequential deep learning models, specifically long-short term memory (LSTM), could capture time-depend features in continuous alarm sequences preceding code blue events and these features may be predictive of these endpoints. LSTM models are trained from continuous alarm sequences in various window lengths preceding code blue events, and the preliminary results showed the best performance reached an AUC of 0.8549. With the selection of optimal cutoff threshold, the 2-hour window model achieved 85.75% sensitivity and 72.61% specificity, respectively.

Background: There is limited experience of surgical epicardial access in the contemporary era of ventricular tachycardia ablation after cardiac surgery., Objectives: The purpose of this study was to describe our institutional experience with surgical epicardial access and the influence of surgical approach and compare outcomes with those of a propensity-matched percutaneous epicardial access control group., Methods: We performed a retrospective study of consecutive surgical epicardial ventricular tachycardia (VT) ablation cases from a single center. Surgical cases were propensity-matched to percutaneous epicardial ablation controls and short-term and long-term outcomes were compared., Results: Between 2004 and 2016, 38 patients underwent 40 surgical epicardial access procedures (subxiphoid, n = 22; thoracotomy, n = 18). The commonest indication was prior coronary artery bypass grafting (45%), valve surgery (22%), or ventricular assist device (VAD) (10%). The mean procedure time was 444 minutes (standard deviation, 107 minutes). Mapped epicardial geometry area was 149 cm 2 (interquartile range 182 cm 2 ), which comprised 36% of the mapped epicardial geometric area of a percutaneous control group. Subxiphoid access gave preferential access to the inferior and inferolateral left ventricular segments and was less frequently able to access the anterior, anterolateral, and apical segments compared with a thoracotomy approach. When compared with results from a propensity-matched percutaneous-access group, short-term outcomes, complication rates, and 1-year survival free from a combined end point of VT recurrence, death, or transplantation were not statistically different., Conclusions: Surgical epicardial access after cardiac surgery for ablation of VT in patients with careful preprocedure evaluation can be performed with acceptable safety with no statistical difference in long-term outcomes compared with a propensity-matched percutaneous epicardial cohort. The region of left ventricular epicardium that can be mapped is limited compared with that of percutaneous cases and is determined by the surgical approach., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Magnetic resonance imaging (MRI) has been performed safely in patients without MRI-conditional cardiac implantable electronic devices (CIEDs), but experience specifically with cardiac magnetic resonance imaging (CMR) is limited in this patient population., Objective: Evaluate the safety of CMR in non-MRI-conditional CIEDs and the interpretability of images using wideband sequences., Methods: We performed 114 consecutive CMR studies in 111 patients (mean age 59 ± 14 years, with 12 pacemakers, 73 implantable cardioverter defibrillators, 29 biventricular defibrillators) using a wideband pulse sequence for late gadolinium enhancement (LGE) imaging. A standardized protocol for device management and patient monitoring was followed. Patients were evaluated for major clinical adverse events and device parameter changes immediately after CMR and at clinical follow-up., Results: In total, 111 CMR studies were completed successfully. There were no patient deaths, new arrhythmias, immediate generator or lead failures, electrical resets, or pacing capture failures in dependent patients. Right atrial, right ventricular, and left ventricular lead impedances were significantly lower post CMR, with median differences -7 Ω (interquartile range [IQR] -20 to 0 Ω; P < .0001), 0 Ω (IQR -19 to 0 Ω; P = .0001), and -10 Ω (IQR -30 to 0 Ω; P = .023), respectively. These changes persisted through the follow-up period, with median differences -18.5 Ω (IQR -41 to -66 Ω; P = .007), -19 Ω (IQR -44 to -7 Ω; P = .006), and -30 Ω (IQR -130 to 0 Ω; P = .003), respectively. Ninety-seven studies (87%) had no artifact limiting interpretation., Conclusions: CMR can be performed safely in non-MRI-conditional CIEDs using a standardized protocol. Use of a wideband pulse sequence for LGE imaging yields a high rate of studies unaffected by artifact., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Infrequent intraprocedural premature ventricular complexes (PVCs) may impede radiofrequency catheter ablation (RFA) outcome, and pharmacologic induction is unpredictable., Objective: The purpose of this study was to determine whether PVC circadian variation could help predict drug response., Methods: Consecutive patients referred for RFA with detailed Holter monitoring and frequent monomorphic PVCs were included. Patients were divided into 3 groups based on hourly PVC count relationship to corresponding mean heart rate (HR) during each of the 24 hours on Holter: fast-HR-dependent PVC (F-HR-PVC) type for a positive correlation (Pearson, P <.05), slow-HR-dependent PVC (S-HR-PVC) type for a negative correlation, and independent-HR-PVC (I-HR-PVC) when no correlation was found., Results: Fifty-one of the 101 patients (50.5%) had F-HR-PVC, 39.6% I-HR-PVC, and 9.9% S-HR-PVC; 30.7% had infrequent intraprocedural PVC requiring drug infusion. The best predictor of infrequent PVC was number of hours with PVC count <120/h on Holter (area under the curve 0.80, sensitivity 83.9%, specificity 74.3%, for ≥2 h). Only F-HR-PVC patients responded to isoproterenol. Isoproterenol washout or phenylephrine infusion was successful for the 3 S-HR-PVC patients, and no drug could increase PVC frequency in the 12 I-HR-PVC patients. Long-term RFA success rate in patients with frequent PVCs at baseline (82.9%) was similar to those with infrequent PVC who responded to a drug (77.8%; P = .732) but significantly higher than for those who did not respond to any drug (15.4%; P <.0001)., Conclusion: A simple analysis of Holter PVC circadian variability provides incremental value to guide pharmacologic induction of PVCs during RFA and predict outcome. Patients with infrequent I-HR-PVC had the least successful outcomes from RF ablation., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Pericardial adhesions can prevent epicardial access and restrict catheter movement during mapping and ablation of ventricular tachycardia (VT). The incidence of adhesions in patients without prior cardiac surgery or clinically evident pericarditis is not known., Objective: To describe the incidence of pericardial adhesions and explore their impact in patients without prior cardiac surgery or pericarditis., Methods: A retrospective search of our ablation database containing patients who underwent epicardial ablation for VT was undertaken. Adhesions were diagnosed with routine contrast pericardiography after pericardial entry. Demographics and long-term outcomes were compared between patients with and without adhesions., Results: Between 2004 and 2016, successful epicardial entry was achieved in 188 of 192 attempts (98%). In 155 first-time epicardial access attempts, pericardial adhesions were diagnosed in 13 (8%). When comparing baseline demographics, there was no significant difference. However, adhesions tended to occur more frequently with severe renal impairment (2% of patients without adhesions vs 15% of patients with adhesions, P = .07). No patient with a structurally normal heart had adhesions present. Adhesions were associated with limited epicardial mapping (3% of patients without adhesions vs 85% of patients with adhesions, P < .001) and lower short-term procedural success (68% of patients without adhesions vs 46% of patients with adhesions, P = .02), but complication rates were similar. The presence of adhesions did not translate into lower VT-free survival (P = .64) or freedom from a combined end point of VT recurrence, death, or transplant at 1 year (P = .93)., Conclusion: Adhesions may be unexpectedly encountered in patients without prior cardiac surgery or pericarditis. When present, they can limit mapping and may be associated with lower short-term success. Larger studies are required to determine their impact on long-term outcomes., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The aim of this study was to determine the temporal trends in utilization of catheter ablation of accessory pathways in the United States., Methods: All patients from the Nationwide Inpatient Sample (NIS) ≥18years of age with a primary diagnosis of anomalous atrioventricular excitation syndrome (International Classification of Diseases, Ninth Edition, Clinical Modification [ICD-9-CM] code 426.7) were included in the study. Patients who underwent catheter ablation were identified using ICD-9-CM procedure code 37.34. Patients with a concomitant diagnosis of atrial fibrillation, atrial flutter, atrial tachycardia or ventricular arrhythmias were excluded from the analysis. Annual hospital volume was identified using unique hospital identification number and was divided into tertiles for further analysis., Results: A total of 11,601 catheter ablations for anomalous atrioventricular excitation syndrome were studied from 1998 to 2011. The mean length of stay was 1.8days (median 1day). The utilization trends of accessory pathway ablation have steadily declined from 3.9 ablation procedures/million US population in 1998-1999 to 2.5 ablation procedures/million US population in 2010-2011. The second tertile (adjusted OR 0.41; 95% CI 0.20-0.83, p=0.01) and third tertile (adjusted OR 0.39; 95% CI 0.18-0.85, p=0.02) of hospital volume were associated with reduction in cardiac complications as compared to first tertile of hospital volume. Advanced age (OR 1.02, 95% CI 1.01-1.04, p=0.002) was independent predictor of cardiac complications. There were no in-hospital deaths., Conclusion: Despite decline in ablation trends, it still remains a relatively safe procedure associated with low morbidity and no mortality., (Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.)

Ventricular arrhythmias remain a significant cause of sudden cardiac death (SCD), and knowledge of their cause and high-risk features is important. SCD occurs when the interaction between vulnerable substrates and acute triggers results in sustained ventricular tachycardia progressing to ventricular fibrillation. Here, the authors aim to review the role of ventricular arrhythmias in SCD, first by approaching the substrates that support ventricular arrhythmias, and then by exploring features of these substrates and the acute triggers that may lead to SCD., (Copyright © 2017 Elsevier Inc. All rights reserved.)