Postapproval Study of a Subcutaneous Implantable Cardioverter-Defibrillator System.

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to avoid complications related to transvenous implantable cardioverter-defibrillator (TV-ICD) leads. Device safety and efficacy were demonstrated previously with atypical clinical patients or limited follow-up.

Objectives: The S-ICD PAS (Subcutaneous Implantable Cardioverter-Defibrillator System Post Approval Study) is a real-world, multicenter, registry of U.

Influence of "high" defibrillation thresholds on patient survival and impact of system modification.

Objective: To test whether a high defibrillation threshold (DFT) marks patients with poor outcomes which are improved when DFT is decreased by system modification (subcutaneous coil implant; SM).

Background: The electrical substrate generating fast ventricular arrhythmias may generate poor outcomes among patients treated with implantable cardioverter-defibrillators (ICDs), even when arrhythmias are treated successfully. Since patients with high DFTs have increased mortality, we contrasted survival among patients with high DFT treated with and without SM.

Acute safety, efficacy, and advantages of a novel cryoballoon ablation system for pulmonary vein isolation in patients with paroxysmal atrial fibrillation: initial clinical experience.

Aims: Cryoballoon pulmonary vein isolation (PVI) is a safe and effective treatment for atrial fibrillation (AF). Current limitations include incomplete vein occlusion due to balloon rigidity and inconsistent electrogram recording, which impairs identification of isolation. We aimed to evaluate the acute safety and performance of a novel cryoballoon system.

Machine Learning of 12-Lead QRS Waveforms to Identify Cardiac Resynchronization Therapy Patients With Differential Outcomes.

Background: Cardiac resynchronization therapy (CRT) improves heart failure outcomes but has significant nonresponse rates, highlighting limitations in ECG selection criteria: QRS duration (QRSd) ≥150 ms and subjective labeling of left bundle branch block (LBBB). We explored unsupervised machine learning of ECG waveforms to identify CRT subgroups that may differentiate outcomes beyond QRSd and LBBB.

Methods: We retrospectively analyzed 946 CRT patients with conduction delay.

Clinical Outcomes and Characteristics With Dofetilide in Atrial Fibrillation Patients Considered for Implantable Cardioverter-Defibrillator.

Background: Dofetilide is one of the only anti-arrhythmic agents approved for atrial fibrillation (AF) in patients with reduced left ventricular ejection fraction (LVEF). However, postapproval data and safety outcomes are limited. In this study, we assessed the incidence and predictors of LVEF improvement, safety, and outcomes in patients with AF with LVEF ≤35% without prior implantable cardioverter defibrillator, cardiac resynchronization therapy, or AF ablation.

Outcomes of subcutaneous implantable cardioverter-defibrillator in dialysis patients: Results from the S-ICD post-approval study.

Background: Patients with chronic renal disease on hemodialysis (HD) have limited vascular access and are at high risk of bacteremia. The subcutaneous implantable cardioverter-defibrillator (S-ICD) avoids vascular access, so it may be advantageous in this patient population.

Objective: The purpose of this study was to report outcomes of patients with end-stage renal disease enrolled in the multicenter S-ICD post-approval study (PAS).

Catheter Ablation in Patients With Cardiogenic Shock and Refractory Ventricular Tachycardia.

Background: There is paucity of data regarding radiofrequency ablation for ventricular tachycardia (VT) in patients with cardiogenic shock and concomitant VT refractory to antiarrhythmic drugs on mechanical support.

Methods: Patients undergoing VT ablation at our center were enrolled in a prospectively maintained registry and screened for the current study (2010-2017).

Results: All 21 consecutive patients with cardiogenic shock and concomitant refractory ventricular arrhythmia undergoing bailout ablation due to inability to wean off mechanical support were included.

Cardiac venous injuries: Procedural profiles and outcomes during left ventricular lead placement for cardiac resynchronization therapy.

Background: Injury to the cardiac venous structures can complicate left ventricular lead placement for cardiac resynchronization therapy (CRT). Little is known about the outcomes of coronary sinus (CS) dissection with or without perforation.

Objective: The purpose of this study was to determine the outcomes in patients who had a CS injury during CRT implantation.

Machine Learning Prediction of Response to Cardiac Resynchronization Therapy: Improvement Versus Current Guidelines.

Background: Cardiac resynchronization therapy (CRT) has significant nonresponse rates. We assessed whether machine learning (ML) could predict CRT response beyond current guidelines.

Methods: We analyzed CRT patients from Cleveland Clinic and Johns Hopkins.

Safety of Oral Dofetilide Reloading for Treatment of Atrial Arrhythmias.

Background: Although dofetilide labeling states that the drug must be initiated or reinitiated with continuous electrocardiographic monitoring and in the presence of trained personnel, the risks of dofetilide reloading justifying repeat hospitalization have not been investigated.

Methods And Results: Patients admitted for dofetilide reloading for atrial arrhythmias were retrospectively reviewed. The need for dose adjustment and the incidence of torsades de pointes (TdP) were identified.

Early Changes in QRS Frequency Following Cardiac Resynchronization Predict Hemodynamic Response in Left Bundle Branch Block Patients.

Introduction: QRS characteristics are the cornerstone of patient selection in cardiac resynchronization therapy (CRT) and the presence of left bundle branch block (LBBB) and baseline QRS ≥150 milliseconds portends a good outcome. We previously showed that baseline QRS frequency analysis adds predictive value to LBBB alone and have hypothesized that a change in frequency characteristics following CRT may produce additional predictive value.

Methods: We examined the QRS frequency characteristics of 182 LBBB patients before and soon after CRT.

QRS frequency characteristics help predict response to cardiac resynchronization in left bundle branch block less than 150 milliseconds.

Background: Baseline QRS duration (QRSd) ≥150 ms is a recognized predictor of clinical improvement by cardiac resynchronization therapy (CRT), particularly for those with left bundle branch (LBBB). Patients with QRSd <150 ms are considered less likely to respond.

Objective: The purpose of this study was to test our theory that left ventricular dyssynchrony, although usually associated with wider QRSd, also exhibits lower QRS frequency characteristics and that low-frequency content predicts CRT response in LBBB patients.

Left ventricular hypertrophy and antiarrhythmic drugs in atrial fibrillation: impact on mortality.

Background: Despite sparse clinical data, current atrial fibrillation (AF) guidelines favor amiodarone as a drug of choice for patients with left ventricular hypertrophy (LVH).

Objective: This study tested the hypothesis that patients with persistent AF and LVH on nonamiodarone antiarrhythmics have higher mortality compared to patients on amiodarone.

Methods: In an observational cohort analysis of patients who underwent cardioversion for AF, patients with LVH, defined as left ventricular wall thickness ≥1.

Clinical predictors of adverse patient outcomes in an experience of more than 5000 chronic endovascular pacemaker and defibrillator lead extractions.

Background: It is difficult to predict adverse patient outcomes associated with transvenous lead extraction (TLE) procedures.

Objective: The purpose of this study was to examine the safety and efficacy of chronic endovascular pacemaker and implantable cardioverter-defibrillator (ICD) lead extraction and risk factors associated with adverse patient outcomes.

Methods: Consecutive patients undergoing TLE at the Cleveland Clinic between August 1996 and August 2011 were included in the analysis.

Transvenous extraction of implantable cardioverter-defibrillator leads under advisory--a comparison of Riata, Sprint Fidelis, and non-recalled implantable cardioverter-defibrillator leads.

Background: Comparative safety and efficacy associated with transvenous lead extraction (TLE) of recalled and non-recalled implantable cardioverter-defibrillator (ICD) leads has not been well characterized.

Objectives: To compare the indications, techniques, and procedural outcomes of recalled vs non-recalled ICD lead extraction procedures.

Methods: TLE procedures performed at our institution from June 2002 to June 2012 in which Riata, Sprint Fidelis, or non-recalled ICD leads were extracted were included in the analysis.

Real-time guidewire localization using impedance-based electroanatomic mapping: experimental results and clinical validation during cryoballoon ablation of atrial fibrillation.

Aims: Cryoballoon ablation is an emerging therapy for atrial fibrillation (AF). However, the Arctic Front cryoballoon (Medtronic) cannot be localized on current electroanatomic mapping (EAM) systems. We describe a technique to visualize guidewires in an impedance-based EAM system.

Implantable cardioverter-defibrillator FDA safety advisories: Impact on patient mortality and morbidity.

Background: A significant proportion of implantable cardioverter-defibrillators (ICDs) have been subject to Food and Drug Administration (FDA) advisories. The impact of device advisories on mortality or patient care is poorly understood. Although estimated risks of ICD generators under advisory are low, dependency on ICD therapies to prevent sudden death justifies the assessment of long-term mortality.

Predictors of response to cardiac resynchronization therapy in patients with a non-left bundle branch block morphology.

Patients with non-left bundle branch block (LBBB) morphologies are thought to derive less benefit from cardiac resynchronization therapy (CRT) than those with LBBB. However, some patients do exhibit improvement. The characteristics associated with a response to CRT in patients with non-LBBB morphologies are unknown.

Aggregate national experience with the wearable cardioverter-defibrillator: event rates, compliance, and survival.

Objectives: The purpose of this study was to determine patient compliance and effectiveness of antiarrhythmic treatment by the wearable cardioverter-defibrillator (WCD).

Background: Effectiveness of the WCD for prevention of sudden death is dependent on event type, patient compliance, and appropriate management of ventricular tachycardia/ventricular fibrillation (VT/VF).

Methods: Compliance and events were recorded in a nationwide registry of post-market release WCDs.

Effectiveness of implantable cardioverter-defibrillator lead coil treatments in facilitating ease of extraction.

Background: Expanded polytetrafluoroethylene (ePTFE) coated and medical adhesive back-filled (MABF) implantable cardioverter-defibrillator (ICD) coils have been promoted to reduce the fibrous ingrowth into coils that can complicate lead extraction.

Objective: The purpose of this study was to test the hypothesis that ePTFE or MABF coatings are associated with greater ease of extraction.

Methods: Consecutive isolated ICD lead extraction cases were identified from a prospectively collected clinical database.

Reduced cardioversion thresholds for atrial fibrillation and flutter using the rectilinear biphasic waveform.

Background: The RLB waveform has been shown to be superior in overall efficacy to the MDS waveform for cardioversion of AF in one prospective study and one large retrospective analysis. However, little is known about the efficacy of the RLB waveform at lower energies.

Objective: This study was undertaken to define the cardioversion thresholds for atrial fibrillation (AF) and flutter (FL) using the rectilinear biphasic (RLB) waveform and compare these to the cardioversion threshold using the conventional monophasic damped sine (MDS) waveform.

Comparison of the rectilinear biphasic waveform with the monophasic damped sine waveform for external cardioversion of atrial fibrillation and flutter.

External cardioversion using the monophasic damped sine (MDS) waveform is successful 70% to 94% of the time when using up to 360 J. The rectilinear biphasic (RLB) defibrillator has been shown to be superior in efficacy to the MDS waveform in atrial cardioversion in a small randomized study. This larger, retrospective study compares the results of the RLB waveform with those of the MDS waveform for cardioversion of atrial fibrillation (AF) and atrial flutter in a large cohort of patients.

QRS duration and prediction of mortality in patients undergoing risk stratification for ventricular arrhythmias.

This study tested the hypothesis that prolonged QRS duration independently predicts long-term mortality in patients who underwent risk stratification and treatment for ventricular arrhythmias. Patients who underwent risk stratification by electrophysiologic study were identified. Electrophysiologic study results were defined as positive if sustained monomorphic ventricular tachycardia was induced.

Nonthoracotomy implantable defibrillator lead extraction: results and comparison with extraction of pacemaker leads.

Extraction of pacemaker leads has been demonstrated to be successful and safe in experienced hands using current tools. Whether application of such techniques and tools yield similar results among patients undergoing extraction of nonthoracotomy implantable defibrillator leads is unknown. This report describes a retrospective analysis of indications, techniques used, and outcome of patients who had a single ventricular nonthoracotomy implantable defibrillator lead extracted at The Cleveland Clinic Foundation.