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.S. centers that was designed to assess long-term S-ICD safety and efficacy in a diverse group of patients and implantation centers. METHODS: Patients were enrolled in 86 U.S. centers with standard S-ICD indications and were observed for up to 5 years. Efficacy endpoints were first and final shock efficacy. Safety endpoints were complications directly related to the S-ICD system or implantation procedure. Endpoints were assessed using prespecified performance goals. RESULTS: A total of 1,643 patients were prospectively enrolled, with a median follow-up of 4.2 years. All prespecified safety and efficacy endpoint goals were met. Shock efficacy rates for discrete episodes of ventricular tachycardia or ventricular fibrillation were 98.4%, and they did not differ significantly across follow-up years (P = 0.68). S-ICD-related and electrode-related complication-free rates were 93.4% and 99.3%, respectively. Only 1.6% of patients had their devices replaced by a TV-ICD for a pacing need. Cumulative all-cause mortality was 21.7%. CONCLUSIONS: In the largest prospective study of the S-ICD to date, all study endpoints were met, despite a cohort with more comorbidities than in most previous trials. Complication rates were low and shock efficacy was high. These results demonstrate the 5-year S-ICD safety and efficacy for a large, diverse cohort of S-ICD recipients. (Subcutaneous Implantable Cardioverter-Defibrillator [S-ICD] System Post Approval Study [PAS]; NCT01736618).

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. METHODS: We studied consecutive patients undergoing ICD implantation and DFT testing at Cleveland Clinic over a 14-year period. High DFT was defined as successful defibrillation by shock strength >25 J or ≤10 J of maximal device output. Mortality was recorded using the Social Security Death Index. Survival was compared among those high DFT patients receiving SM versus the remainder. RESULTS: Out of 6353 patients tested, 191 (3%) had high DFT (32.1 ± 3.7 J) versus 13.9 ± 4.9 J in the remainder ("acceptable DFT," p < .001). One hundred twenty-one high DFT patients (63%; 33.3 ± 3.4 J) underwent SM, which significantly decreased DFT (24.8 ± 5.9 J; p < .001). Seventy patients (37%; 30.3 ± 3.3 J) did not undergo SM. During follow-up, 38% (2363/6162; 7.8 yrs) patients with acceptable DFT died versus 48% high DFT patients (91/191; 5.6 yrs.; p < .001). Concomitantly, 48% patients with SM (58/121) died, as compared to 47% patients (33/70) without SM (p = .91); median follow-up 4.9 yrs). CONCLUSION: Patients with high DFT have a higher mortality than those with acceptable DFT. The additional subcutaneous coil implant decreases DFT to an acceptable range but does not appear to improve survival. The electrical substrate underlying high DFT appears to determine survival.

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. METHODS AND RESULTS: The system includes a steerable sheath, mapping catheter, and a balloon that maintains uniform inflation pressure and size following initiation of ablation. Protocol-directed cryoablation was delivered for 180 s for isolation documented in ≤60 s, otherwise freeze duration was 240 s. Primary endpoints were acute safety and vein isolation. Pulmonary vein isolation was confirmed at ≥30 min post-isolation. Data were compared across vein locations. Thirty patients with paroxysmal AF were enrolled at two centres and underwent PVI. Pulmonary vein isolation was achieved with cryoablation only in 100% of veins (120/120). Nadir temperature was -53.1 ± 5.3°C. The number of applications to achieve PVI was 1.4 ± 0.4 per vein. Of the 120 veins, 89 were isolated with a single cryothermal application (10/30 patients required only 4 total cryoablations). There were no procedural- or device-related serious adverse events at 30 days post-procedure. A subset (24/30) of patients was followed for 1-year and 71% (17/24) remained free of atrial arrhythmias. Six patients with arrhythmia recurrence were remapped and three had durable PVI for all four veins. CONCLUSION: In this first human experience, the novel cryoballoon platform was safe, efficacious, and demonstrated a high proportion of successful single ablation isolation.

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. METHODS: An analysis of 168 consecutive patients from 2007 to 2016 was performed. Incidences of adverse events, drug continuation, implantable cardioverter defibrillator and cardiac resynchronization therapy implantation, LVEF improvement (>35%) and recovery (≥50%), AF recurrence, and AF ablation were determined. Multivariable regression analysis to identify predictors of LVEF improvement/recovery was performed. RESULTS: The mean age was 64±12 years. Dofetilide was discontinued before hospital discharge in 46 (27%) because of QT prolongation (14%), torsades de pointe or polymorphic ventricular tachycardia/fibrillation (6% [sustained 3%, nonsustained 3%]), ineffectiveness (5%), or other causes (3%). At 1 year, 43% remained on dofetilide. Freedom from AF was 42% at 1 year, and 40% underwent future AF ablation. LVEF recovered (≥50%) in 45% and improved to >35% in 73%. Predictors of LVEF improvement included presence of AF during echocardiogram (odds ratio, 4.22 [95% CI, 1.71-10.4], P=0.002), coronary artery disease (odds ratio, 0.35 [95% CI, 0.16-0.79], P=0.01), left atrial diameter (odds ratio, 0.52 per 1 cm increase [95% CI, 0.30-0.90], P=0.01), and LVEF (odds ratio, per 1% increase, 1.09 [95% CI, 1.02-1.16], P=0.006). The C statistic was 0.78. CONCLUSIONS: In patients with LVEF ≤35%, who are potential implantable cardioverter defibrillator candidates, treated with dofetilide as an initial anti-arrhythmic strategy for AF, drug discontinuation rates were high, and many underwent future AF ablation. However, most patients had improvement in LVEF, obviating the need for primary prevention implantable cardioverter defibrillator.

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. Principal component analysis (PCA) dimensionality reduction obtained a 2-dimensional representation of preCRT 12-lead QRS waveforms. k-means clustering of the 2-dimensional PCA representation of 12-lead QRS waveforms identified 2 patient subgroups (QRS PCA groups). Vectorcardiographic QRS area was also calculated. We examined following 2 primary outcomes: (1) composite end point of death, left ventricular assist device, or heart transplant, and (2) degree of echocardiographic left ventricular ejection fraction (LVEF) change after CRT. RESULTS: Compared with QRS PCA Group 2 (n=425), Group 1 (n=521) had lower risk for reaching the composite end point (HR, 0.44 [95% CI, 0.38-0.53]; P<0.001) and experienced greater mean LVEF improvement (11.1±11.7% versus 4.8±9.7%; P<0.001), even among patients with LBBB with QRSd ≥150 ms (HR, 0.42 [95% CI, 0.30-0.57]; P<0.001; mean LVEF change 12.5±11.8% versus 7.3±8.1%; P=0.001). QRS area also stratified outcomes but had significant differences from QRS PCA groups. A stratification scheme combining QRS area and QRS PCA group identified patients with LBBB with similar outcomes to non-LBBB patients (HR, 1.32 [95% CI, 0.93-1.62]; difference in mean LVEF change: 0.8% [95% CI, -2.1% to 3.7%]). The stratification scheme also identified patients with LBBB with QRSd <150 ms with comparable outcomes to patients with LBBB with QRSd ≥150 ms (HR, 0.93 [95% CI, 0.67-1.29]; difference in mean LVEF change: -0.2% [95% CI, -2.7% to 3.0%]). CONCLUSIONS: Unsupervised machine learning of ECG waveforms identified CRT subgroups with relevance beyond LBBB and QRSd. This method may assist in objective classification of bundle branch block morphology in CRT.

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). METHODS: S-ICD PAS patients were stratified on the basis of the presence (group 1) or absence (group 2) of HD at the time of implantation. Baseline demographic and clinical characteristics were collected. Perioperative and intermediate-term outcomes 365 days postimplantation were compared between the 2 groups. RESULTS: There were 220 patients on HD (13.4%) at the time of implantation out of 1637 patients enrolled in the S-ICD PAS. Patients on HD (group 1) were older (57.4 ± 13.2 years vs 52.5 ± 15.2 years; P < .0001), more likely to be of African descent (48.6% vs 25.1%; P < .0001), and had lower ejection fraction (28.6% ± 11.3% vs 32.6% ± 14.9%; P < .0001) as compared with patients not on HD (group 2). Group 1 had more comorbidities and mortality was higher (17.4% vs 3.7%) than did group 2. The rate of complications calculated using the Kaplan-Meier estimate did not differ between the 2 groups (overall P = .9169), with a 1-year rate of 7.9% and 7.7% for groups 1 and 2, respectively. The rate of appropriate shocks was significantly higher in group 1 (Kaplan-Meier analysis, P = .0003), as was inappropriate shocks (P = .0137). CONCLUSION: S-ICD is associated with similar adverse event rates but a higher risk of inappropriate and appropriate therapy in dialysis patients than in nondialysis patients.

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. Median age was 61 years, 86% were men, median left ventricular ejection fraction was 20%, 81% had ischemic cardiomyopathy, and PAINESD score was 18±5. The type of mechanical support in place before the procedure was intra-aortic balloon pump in 14 patients (67%), Impella CP in 2, extracorporeal membrane oxygenation in 2, extracorporeal membrane oxygenation and intra-aortic balloon pump in 2, and extracorporeal membrane oxygenation and Impella CP in 1. Endocardial voltage maps showed myocardial scar in 19 patients (90%). The clinical VTs were inducible in 13 patients (62%), whereas 6 patients had premature ventricular contraction-induced ventricular fibrillation/VT (29%), and VT could not be induced in 2 patients (9%). Activation mapping was possible in all 13 with inducible clinical VTs. Substrate modification was performed in 15 patients with scar (79%). After ablation and scar modification, the arrhythmia was noninducible in 19 patients (91%). Seventeen (81%) were eventually weaned off mechanical support successfully, but 6 (29%) died during the index admission from persistent cardiogenic shock. Patients who had ventricular arrhythmia and cardiogenic shock on presentation had a trend toward lower in-hospital mortality compared with those who presented with cardiogenic shock and later developed ventricular arrhythmia. CONCLUSIONS: Bailout ablation for refractory ventricular arrhythmia in cardiogenic shock allowed successful weaning from mechanical support in a large proportion of patients. Mortality remains high, but the majority of patients were discharged home and survived beyond 1 year.

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. METHODS: All patients undergoing procedures for CRT implantation at the Cleveland Clinic (2001-2018) were enrolled in a prospectively maintained registry for procedural profiles and complications. All patients with cardiac venous injuries during the procedures were included. RESULTS: CS injury occurred in 35 of 5011 patients (0.7%; 6 perforations (17.1%), 29 dissections without perforation (82.9%)). In patients with dissection in the absence of perforation, attempts at CS lead placement after dissection were successful in 21 of 29 patients (72.4%). In those with perforation (n=6, 17.1%), CS lead placement was successful in one of them (16.7%). Cardiac tamponade occurred in 2 patients (5.7%), and the procedure was aborted in both of them. Overall, CS lead placement failed in 13 patients (37%) but 9 (25.7%) underwent subsequent CRT with CS lead placement (n=6, 17.1%; median 58 days later) or epicardial leads (n=3, 8.6%). Three of the remaining 4 patients (8.6%) refused to undergo further procedures, and the fourth (2.9%) died of a complicated course. CONCLUSION: CS injury is not common during CRT implantation procedures and did not preclude successful lead placement in 23 of 35 patients (65.7%) during the index procedure and 6 of 6 (100%) during the subsequent attempted procedures. A low rate of mortality was observed in such patients, but CS injury was associated with increased morbidity.

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. A training cohort was created from all Johns Hopkins patients and an equal number of randomly sampled Cleveland Clinic patients. All remaining patients comprised the testing cohort. Response was defined as ≥10% increase in left ventricular ejection fraction. ML models were developed to predict CRT response using different combinations of classification algorithms and clinical variable sets on the training cohort. The model with the highest area under the curve was evaluated on the testing cohort. Probability of response was used to predict survival free from a composite end point of death, heart transplant, or placement of left ventricular assist device. Predictions were compared with current guidelines. RESULTS: Nine hundred twenty-five patients were included. On the training cohort (n=470: 235, Johns Hopkins; 235, Cleveland Clinic), the best ML model was a naive Bayes classifier including 9 variables (QRS morphology, QRS duration, New York Heart Association classification, left ventricular ejection fraction and end-diastolic diameter, sex, ischemic cardiomyopathy, atrial fibrillation, and epicardial left ventricular lead). On the testing cohort (n=455, Cleveland Clinic), ML demonstrated better response prediction than guidelines (area under the curve, 0.70 versus 0.65; P=0.012) and greater discrimination of event-free survival (concordance index, 0.61 versus 0.56; P<0.001). The fourth quartile of the ML model had the greatest risk of reaching the composite end point, whereas the first quartile had the least (hazard ratio, 0.34; P<0.001). CONCLUSIONS: ML with 9 variables incrementally improved prediction of echocardiographic CRT response and survival beyond guidelines. Performance was not improved by incorporating more variables. The model offers potential for improved shared decision-making in CRT (online calculator: http://riskcalc.org:3838/CRTResponseScore ). Significant remaining limitations confirm the need to identify better variables to predict CRT response.

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. The incidence of TdP in dofetilide reloading was compared with patients admitted for dofetilide initial loading. Of 138 patients admitted for dofetilide reloading for atrial arrhythmias, 102 were reloaded at a previously tolerated dose, 30 with a higher dose from a previously tolerated dose and 2 at a lower dose; prior dosage was unknown in 4 patients. Dose adjustment or discontinuation was required in 44 patients (31.9%). No TdP occurred in the same dose reloading group, but TdP occurred in 2 patients admitted to increase dofetilide dosage (0% versus 6.7%; P=0.050). Dofetilide dose adjustment or discontinuation was required in 30 of 102 patients (29.4%) reloaded at a previously tolerated dose and in 11 of 30 patients (36.7%) admitted for an increase in dose. CONCLUSIONS: Although no TdP occurred in patients admitted to reload dofetilide at the same dose as previously tolerated, dosage adjustments or discontinuation was frequent and support the need for hospitalization for dofetilide reloading. Patients admitted for reloading with a higher dose tended to be at higher risk for TdP than patients reloaded at a prior tolerated dose.

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. Patients were assigned to responder and nonresponder groups. Responders were defined by a decrease in left ventricular end-systolic volume (LVESV) ≥15% following CRT. We analyzed the QRS in ECG leads I, AVF, and V3 before and soon after CRT using the discrete Fourier transform algorithm. The percentage of total QRS power within discrete frequency intervals before and after CRT was calculated. The reduction in lead V3 power <10 Hz was the best indicator of response. RESULTS: Baseline QRS width was similar between the responders and nonresponders (162.2 ± 17.2 milliseconds vs. 158 ± 22.1 milliseconds, respectively; P = 0.180). Responders exhibited a greater reduction in QRS power <10 Hz (-17.0 ± 11.9% vs. -6.6 ± 12.5%; P < 0.001) and a significant AUC (0.743; P < 0.001). A ≥8% decline in QRS power <10 Hz produced the best predictive values (PPV = 84%, NPV = 59%). Importantly, when patients with baseline QRS <150 milliseconds were compared, the AUC improved (0.892, P < 0.001). CONCLUSIONS: Successful CRT produces a significant reduction in QRS power below 10 Hz, particularly when baseline QRS <150 milliseconds. These results indicate that QRS frequency changes after CRT provide additional predictive value to QRS alone.

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. METHODS: We retrospectively examined the QRS frequency content of 170 heart failure patients with LBBB and QRSd ≥120 ms using Fourier transformation. Ninety-four responders to CRT (defined as reduction in left ventricular end-systolic volume by ≥15% from baseline) were compared to 76 nonresponders (<15% reduction). Analysis of 3 standard ECG leads (I, aVF, and V3) representing the 3 dimensions of depolarization was performed, and V3 provided the best predictive value. RESULTS: The QRSd of responders (160.3 ± 17.8 ms) and nonresponders (161.8 ± 21.1 ms, P = .604) were similar. We found that the percentage of total QRS frequency power below 10 Hz that exceeded 52% was most predictive of CRT response compared to other cutoff values. However, the percentage of patients with total QRS power >52% below 10 Hz was especially predictive of response in those with QRSd <150 ms. In these patients, this power threshold was highly predictive of CRT response (positive predictive value 85.7%, negative predictive value 71.4%). CONCLUSION: In this group of CRT recipients with LBBB, retrospective analysis of QRS frequency content below 10 Hz had greater predictive value for CRT response than baseline QRSd, particularly in those with QRSd <150 ms.

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 ≥1.4 cm, by echocardiogram prior to their first cardioversion, were included; clinical data, including antiarrhythmic drugs and ejection fraction (LVEF), were collected. Mortality, determined via the Social Security Death Index, was analyzed using Kaplan-Meier and Cox proportional hazards models to determine whether antiarrhythmic drugs were associated with higher mortality. RESULTS: In 3,926 patients, echocardiographic wall thickness was available in 1,399 (age 66.8 ± 11.8 years, 67% male, LVEF 46 ± 15%, septum 1.3 ± 0.4, posterior wall 1.2 ± 0.2 cm), and 537 (38%) had LVH ≥1.4 cm. Among 537 patients with LVH, mean age was 67.5 ± 11.7 years, 76.4% were males, and mean LVEF was 48.3 ± 13.3%. Amiodarone was associated with lower survival (log rank P = 0.001), including after adjusting for age, LVEF, and coronary artery disease (P = 0.023). In propensity-score matched cohorts with LVH treated with no drugs, nonamiodarone antiarrhythmic drugs (non-AADs), or amiodarone (N = 65 each group), there was early lower survival in patients on amiodarone (P = 0.05). CONCLUSIONS: Patients with persistent AF and LVH on non-AADs do not have higher mortality compared to patients on amiodarone. Importantly, these findings do not support amiodarone as a superior choice in patients with LVH.

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. Univariate and multivariable logistic regression analyses were performed to evaluate for associations with outcomes. Continuous data are given as median (25th, 75th percentile). Categorical data are given as number (percentage). RESULTS: In total, 5521 leads (4137 [74.9%] pacemaker, 1384 [25.1%] ICD) were extracted during 2999 TLE procedures (patient age 67.2 [55.2, 76.2] years, 30.2% female). Lead implant duration was 4.7 (2.4, 8.3) years, and 2.0 (1.0, 2.0) leads were extracted per procedure. Powered sheaths were used in 74.9% of procedures. Overall, there was 95.1% complete procedural success, 98.9% clinical success, and 1.1% failure, with 3.6% minor complications and 1.8% major complications. All-cause mortality within 30 days of TLE was 2.2%. Multivariable predictors of major complications included cerebrovascular disease, ejection fraction ≤15%, lower platelet count, international normalized ratio ≥1.2, mechanical sheaths, and powered sheaths. Multivariable predictors of all-cause mortality within 30 days of TLE included body mass index <25 kg/m(2), end-stage renal disease, higher New York Heart Association functional class, lower hemoglobin, higher international normalized ratio, lead extraction for infection, and extraction of a dual-coil ICD lead. CONCLUSION: TLE in this single-center experience was highly successful. Risk factors associated with adverse patient outcomes were identified.

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. RESULTS: ICD lead extraction procedures were performed in 1079 patients, including 430 patients with recalled leads (121 Riata, 308 Sprint Fidelis, and 1 Riata and Sprint Fidelis) and 649 patients with non-recalled ICD leads. A total of 2056 chronic endovascular leads were extracted, of which 1215 (59.1%) were ICD leads. Overall, there was 96.8% complete procedural success, 99.1% clinical success, and 0.9% failure, with 3.9% minor complications and 1.5% major complications. Procedural outcomes for Riata and Sprint Fidelis TLE procedures were no different. Lead implant duration was significantly less in recalled than in non-recalled ICD lead TLE procedures. Complete procedural success was higher in recalled (424 of 430 [98.6%]) than in non-recalled (621 of 649 [95.7%]; P = .007) ICD lead TLE procedures. Minor complications were lower in recalled (10 of 430 [2.3%]) than in non-recalled (32 of 649 [5.0%]; P = .030) ICD lead TLE procedures. Rates of clinical success, failure, and major complications were no different in the recalled and non-recalled ICD lead TLE procedures. CONCLUSION: In our experience, recalled ICD leads were extracted with safety and efficacy comparable to that of non-recalled ICD leads.

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. METHODS AND RESULTS: A novel technique for real-time guidewire localization in an EAM (Ensite Velocity, St Jude Medical) was prospectively evaluated among patients referred for cryoballoon AF ablation. The guidewire was visualized as an 'orb' on the EAM and localization in each of the pulmonary veins (PVs) compared with orthogonal fluoroscopy, contrast venography, and intra-cardiac echocardiography. Application of the technique in 21 consecutive patients [median age 58 (interquartile range 21); 71.4% male; 85.7% paroxysmal AF] demonstrated agreement with respect to guidewire localization in 82 of 82 (100%) PVs. Discrimination of guidewire position in the left atrial appendage from the left PVs was also demonstrated. When compared with 21 consecutive cryoballoon procedures over the same time period in which the technique was not used, fluoroscopy time was reduced [median 53.2 (25.9) vs. 72.3 (47.6) min, P = 0.008], and a trend towards reduced radiation exposure [median 372 (656.0) vs. 581 (849.9) mGy, P = 0.08] was noted, without effect on acute procedural or mid-term endpoints. Ex vivo assessment of the technique in a saline bath left atrial model demonstrated that the 'orb' localizes to the centroid of the exposed portion of the guidewire. CONCLUSION: This simple, novel technique provides real-time, accurate guidewire localization to enable guidewire and catheter navigation during cryoballoon AF ablation.

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. OBJECTIVE: To test the association of FDA advisory status with long-term mortality. METHODS: The study was a retrospective, single-center review of clinical outcomes, including device malfunctions, in patients from implantation to either explant or death. Patients with ICDs first implanted at Cleveland Clinic between August 1996 and May 2004 who became subject to FDA advisories on ICD generators were identified. Mortality was determined by using the Social Security Death Index. RESULTS: In 1644 consecutive patients receiving first ICD implants, 704 (43%) became subject to an FDA advisory, of which 172 (10.5%) were class I and 532 (32.3%) were class II. ICDs were explanted before advisory notifications in 14.0% of class I and 10.1% of class II advisories. Among ICDs under advisory, 28 (4.0%) advisory-related and 15 non-advisory- related malfunctions were documented. Over a median follow-up of 70 months, 814 patients died. Kaplan-Meier 5-year survival rate was 65.6% overall, and 64.2, 61.1, and 69.3% in patients with no, class I, and class II advisories, respectively (P = .17). CONCLUSIONS: ICD advisories impacted 43% of the patients. Advisory-related malfunctions affected 4% within the combined advisory group. Based on a conservative management strategy, ICDs under advisory were not associated with increased mortality over a background of significant disease-related 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. Clinical, electrocardiographic, and echocardiographic data were collected from 850 consecutive patients presenting for a new CRT device. For inclusion, all patients had a left ventricular ejection fraction of ≤35%, a QRS duration of ≥120 ms, and baseline and follow-up echocardiograms available. Patients with a paced rhythm or LBBB were excluded. The response was defined as an absolute decrease in left ventricular end-systolic volume of ≥10% from baseline. Multivariate models were constructed to identify variables significantly associated with the response and long-term outcomes. A total of 99 patients met the inclusion criteria. Of these 99 patients, 22 had right bundle branch block and 77 had nonspecific intraventricular conduction delay; 52.5% met the criteria for response. On multivariate analysis, the QRS duration was the only variable significantly associated with the response (odds ratio per 10-ms increase 1.23, 95% confidence interval 1.01 to 1.52, p = 0.048). During a mean follow-up of 5.4 ± 0.9 years, 65 patients died or underwent heart transplant or left ventricular assist device placement. On multivariate analysis, the QRS duration was inversely associated with poor long-term outcomes (hazard ratio per 10-ms increase 0.79, 95% confidence interval 0.66 to 0.94, p = 0.005). In patients with advanced heart failure and non-LBBB morphologies, a wider baseline QRS duration is an important determinant of enhanced reverse ventricular remodeling and improved long-term outcomes after CRT.

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. Survival, using the Social Security Death Index, was compared with survival in implantable cardioverter-defibrillator (ICD) patients. RESULTS: Of 3,569 patients wearing the WCD (age 59.3+/-14.7 years, duration 52.6+/-69.9 days), daily use was 19.9+/-4.7 h (>90% of the day) in 52% of patients. More days of use correlated with higher daily use (p<0.001). Eighty sustained VT/VF events occurred in 59 patients (1.7%). First-shock success was 76 of 76 (100%) for unconscious VT/VF and 79 of 80 (99%) for all VT/VF. Eight patients died after successful conversion of unconscious VT/VF (89.5% survival of VT/VF events). Asystole occurred in 23 (17 died), pulseless electrical activity in 2, and respiratory arrest in 1 (3 died), representing 24.5% of sudden cardiac arrests. During WCD use, 3,541 of 3,569 patients (99.2%) survived overall. Survival occurred in 72 of 80 (90%) VT/VF events and 78 of 106 (73.6%) for all events. Long-term mortality was not significantly different from first ICD implant patients but highest among patients with traditional ICD indications. CONCLUSIONS: Compliance was satisfactory with 90% wear time in >50% of patients and low sudden death mortality during use. Survival was comparable to that of ICD patients. However, asystole was an important cause of mortality in sudden cardiac arrest events.