Search

Background: Previous studies have demonstrated that microvolt T-wave alternans (MTWA) testing is a robust predictor of ventricular tachyarrhythmias and sudden cardiac death (SCD) in at-risk patients. However, recent studies have suggested that MTWA testing is not as good a predictor of "appropriate" implantable cardioverter-defibrillator (ICD) therapy as it is a predictor of SCD in patients without ICDs.Objective: To evaluate the utility of MTWA testing for SCD risk stratification in patients without ICDs.Methods: Patient-level data were obtained from 5 prospective studies of MTWA testing in patients with no history of ventricular arrhythmia or SCD. In these studies, ICDs were implanted in only a minority of patients and patients with ICDs were excluded from the analysis. We conducted a pooled analysis and examined the 2-year risk for SCD based on the MTWA test result.Results: The pooled cohort included 2883 patients. MTWA testing was positive in 856 (30%), negative in 1627 (56%), and indeterminate in 400 (14%) patients. Among patients with a left ventricular ejection fraction (LVEF) of ≤35%, annual SCD event rates were 4.0%, 0.9%, and 4.6% among groups with MTWA positive, negative, and indeterminate test results. The SCD rate was significantly lower among patients with a negative MTWA test result than in patients with either positive or indeterminate MTWA test results (P <.001 for both comparisons). In patients with an LVEF of >35%, annual SCD event rates were 3.0%, 0.3%, and 0.3% among the groups with MTWA positive, negative, and indeterminate test results. The SCD rate associated with a positive MTWA test result was significantly higher than that associated with either negative (P <.001) or indeterminate MTWA test results (P = .003).Conclusions: In patients without ICDs, MTWA testing is a powerful predictor of SCD. Among patients with an LVEF of ≤35%, a negative MTWA test result is associated with a low risk for SCD. Conversely, among patients with an LVEF of >35%, a positive MTWA test result identifies patients at significantly heightened SCD risk. These findings may have important implications for refining primary prevention ICD treatment algorithms. [ABSTRACT FROM AUTHOR]

Background: Transvenous Lead extraction (TLE) success and safety are heavily influenced by lead dwell time., Objective: In this study, we aim to compare the clinical effectiveness and safety of transvenous lead extraction between young and old leads., Methods: We retrospectively identified all TLE procedures at Emory Healthcare from 2007-2023. Baseline patients' characteristics and procedural details were collected. The cohort was categorized based on the oldest lead dwell time in each procedure. The very long-dwell time (VLDT) group included all procedures with the oldest lead dwell time ≥15 years, whereas the control group included all procedures with the oldest lead dwell time <15 years. TLE outcomes were compared between the 2 groups., Results: Of the 1717 TLE procedures, 114 procedures (6.6%) included leads with dwell times ≥15 years. Patients in the VLDT group were older and had a higher number of targeted leads. 57% of TLE in the VLDT group were for infectious indications. Lead extraction procedural and clinical success were significantly lower in the VLDT group compared to the control group (75% vs 95%, 83% vs 97%, p<0.001, respectively). There was a trend towards a higher major complications rate in the VLDT group compared to the control group (3.5% vs 1.3%, p=0.058)., Conclusion: TLE of VLDT leads has a lower procedural and clinical success and a higher complication rate than TLE of leads with a shorter dwell time. These results will allow electrophysiologists to quantify risks and benefits of abandoning leads at the time of lead revisions or upgrades., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Because of differences in chest wall anatomy, female patients may have higher rates of subcutaneous implantable cardioverter-defibrillator (S-ICD) pocket-related complications., Objective: We sought to evaluate sex-based outcomes after S-ICD implantation., Methods: Patients implanted with an S-ICD at Emory Healthcare between 2010 and 2023 were included in the analysis. Patients' clinical characteristics and post-S-ICD implantation complications were collected., Results: There were 429 male patients (68%) and 199 female patients (32%) observed for a median duration of 2.3 years (0.6-4.4 years). Male and female patients had comparable rates of diabetes (28%), end-stage renal disease (29.5%), ejection fraction (30.2% ± 13.4%), and body mass index (29.1 ± 6.6 kg/m 2 ). There was no statistical difference in the incidence of shocks between men and women (26.3% vs 20.1%; P = .09), including appropriate shocks (14.7% vs 12%; P = .98) and inappropriate shocks (11.7% vs 9.5%; P = .98). Pocket-related complications occurred in 21 patients; these included pocket infection (n = 12), wound dehiscence (n = 7), and hematoma requiring drainage (n = 2). Female patients had a significantly higher pocket-related complication rate compared with male patients (7.2% vs 2.5%; P = .016). In controlling for age, body mass index, diabetes, and end-stage renal disease, female patients had higher odds of pocket-related complications compared with male patients (odds ratio, 3.15; 95% confidence interval, 1.27-7.75). Pocket-related complications decreased after 2018 compared with before 2018 (6% vs 2.6%, P = .052), mainly driven by reduction in complications in women (12.3% vs 3.2%; P = .034) but not in men (2.8% vs 2.4%; P = 1)., Conclusion: In this cohort of S-ICD patients, women had a higher rate of post-S-ICD pocket-related complications that could be explained by sex-based differences in anatomy., Competing Interests: Disclosures V.J. received funding from the Katz foundation. B.R.R. received funding from NIH and AHRQ. D.B.D. is a consultant for Boston Scientific, Abbott, and AtriCure. M.S.L. is a consultant for Medtronic and Boston Scientific. M.F.E. is a consultant for Medtronic and Boston Scientific., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Lead-related venous stenosis and occlusion can complicate the insertion or replacement of transvenous leads in patients with cardiac implantable electronic devices (CIEDs). A possible solution is to tunnel the lead from the contralateral vasculature to the ipsilateral generator. Procedural complications and long-term outcomes remain unclear with this technique., Objective: We sought to assess outcomes of tunneled transvenous leads., Methods: We retrospectively identified all patients who underwent transvenous CIED lead tunneling to a contralateral pocket at our institution between 2014 and 2024. Clinical characteristics, indications for lead implantation, postoperative complications, and long-term outcomes were collected., Results: We identified that 27 patients underwent transvenous lead tunneling at our institution. Most patients were men (20, 74%) with a mean age of 68.8 ± 18.3 years. Most patients had nonischemic cardiomyopathy (16, 59%) with a mean ejection fraction of 29.3% ± 11.3%. The tunneled leads were coronary sinus leads (20, 74%), followed by defibrillator leads (5, 18.5%) and right ventricular pacing leads (2, 7.4%). Implantation procedures were primarily for device upgrade (18), lead revisions (8), or de novo lead placement (1). No postoperative complications were seen. Patients were followed for a mean of 2.2 ± 1.4 years. One tunneled defibrillator lead (3.7%) had low shock impedance 3 years after implantation, which was monitored and did not require an intervention., Conclusion: In patients with ipsilateral venous occlusion, contralateral lead tunneling appears to be an effective and safe approach to manage patients with CIEDs and occluded ipsilateral subclavian veins., Competing Interests: Disclosures Dr El-Chami is a consultant for Medtronic and Boston Scientific. The rest of the authors report no conflicts of interest., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Human in vivo data on the chemical stability of different transvenous lead materials, particularly Optim TM leads, are lacking., Objectives: The purpose of this study was to determine the chemical reactivity of insulation materials by analyzing the molar mass of extracted pacing and defibrillator leads METHODS: We collected extracted leads at Emory University Hospitals and sent the leads with thermoplastic outer insulation material for molar mass analysis, a material characteristic that informs biostability. Leads were separated based on the chemical identity of the outer insulation material, and the molar mass was measured by an independent party. The extent of chemical reaction was compared across leads having different materials: poly(ether)urethane 55D, poly(ether)urethane 80A, and Optim., Results: A total of 70 leads were extracted. The subset of extracted leads having outer insulation materials composed of PEU or Optim were analyzed for molar mass, where implant times ranged from 0.12 to 16.26 years. The rate of chemical degradation was compared by plotting the extent of reaction [M n (t = 0)/M n (t)] as a function of implant time. The Optim molar mass decreased to 40% of its initial value at 10 years of implant. No change in the molar mass of the PEU insulations could be resolved over the same 10-year implant time., Conclusion: Because the molar mass of a polymer is directly related to its mechanical integrity, the observed decrease in molar mass of Optim likely translates into premature insulation defects and is consistent with the observed increased rate of electrical malfunction/noise in this subset of cardiac leads., Competing Interests: Disclosures Dr El-Chami reports honoraria/speaking/consulting fees from Boston Scientific and Medtronic. Dr Lloyd reports honoraria/speaking/consulting fees from Medtronic and Boston Scientific. Dr Chaffin is an employee of Medtronic. All other authors have no conflicts to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Data on transvenous (TV) lead-associated superior vena cava (SVC) syndrome are limited. The management of this problem might require a multidisciplinary approach, often involving transvenous lead extraction (TLE) followed by angioplasty and stenting., Objective: The purpose of this study was to describe the management and outcome of TV lead-associated SVC syndrome., Methods: We retrospectively identified patients with a diagnosis of SVC syndrome and TV leads at Emory Healthcare between 2015 and 2023., Results: Fifteen patients with lead-related SVC syndrome were identified. The cohort average age was 50 years. Symptoms included swelling of the face, neck, and upper extremities (67%); shortness of breath (53%); and lightheadedness (40%). Patients had an average of 2 ± 0.7 leads crossing the SVC, with a lead dwell time of 9.8 ± 7.5 years. Thirteen patients were managed with TLE, followed by SVC stenting and angioplasty in 10 and angioplasty alone in 2; 1 patient had no intervention after TLE. One patient was managed with anticoagulation, and another had angioplasty and stenting with lead jailing. One patient experienced SVC perforation and cardiac tamponade during SVC stenting, which was managed successfully with a covered stent and pericardiocentesis. Among the 12 patients with TLE and angioplasty ± stenting, 7 underwent reimplantation of a transvenous lead. Two of those patients had symptoms recurrence, and none of the 5 patients without lead reimplantation had recurrence of symptoms., Conclusion: Lead-related SVC syndrome management requires a multidisciplinary approach often including TLE followed by angioplasty and stenting. Avoiding TV lead reimplantation might help reduce symptoms recurrence., Competing Interests: Disclosures Dr El-Chami is a consultant for Medtronic and Boston Scientific. All other authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Same-day discharge (SDD) after cardiovascular procedures is rapidly gaining ground., Objective: We sought to evaluate the safety of SDD after transvenous lead extraction (TLE)., Methods: We performed a retrospective chart review of patients who underwent elective TLE between January 2020 and October 2021 at our institution. The primary outcome was SDD, and major procedural complications and readmissions within 30 days of the procedure were secondary outcomes., Results: In this analysis of 111 patients who underwent elective TLE, 80 patients (72%) were discharged on the same day (SDD group) while 31 patients (28%) stayed overnight (overnight group). Lead malfunction was the most common indication for TLE in both groups. Patients in the overnight group were more likely to have a lead dwell time of ≤10 years than those in the SDD group (38.7% vs 20% of all leads in each group; P = .042), have laser sheaths used for extraction and a higher number of leads extracted. No major complications were reported in both groups. In a multivariate analysis, lower body mass index and the use of laser sheath during TLE were predictors of overnight stay. Patients who underwent a procedure using advanced extraction techniques were 3.5 times more likely to stay overnight (95% confidence interval 1.27-9.78; P = .016)., Conclusion: In appropriately selected patients undergoing elective lead extraction, SDD is feasible and safe. Higher body mass index, fewer extracted leads, shorter lead dwell times (<10 years), and less frequent use of laser-powered extraction sheaths were associated with an increased likelihood of SDD., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Wider availability of continuous rhythm monitoring has made feasible the incorporation of metrics of atrial fibrillation (AF) burden and duration into the decision to initiate anticoagulation. However, the relationship between thresholds of burden and duration and underlying risk factors at which anticoagulation should be considered remains unclear., Objective: The purpose of this study was to evaluate the relationships of these metrics with each other and the outcome of stroke/transient ischemic attack (TIA)., Methods: We identified patients with cardiovascular implantable electronic devices (CIEDs) with atrial leads who had at least 1 interrogation in 2016 demonstrating nonpermanent AF and were not receiving oral anticoagulation (OAC). We evaluated the relationship between burden (ie, percentage of time spent in AF), the longest single episode of AF, and risk factors (ie, CHA 2 DS 2 -VASc score) in predicting risk of stroke/TIA., Results: The study included 384 patients with mean follow-up of 3.2 ± 0.8 years and incidence of stroke/TIA of 14.8% during follow-up (∼4.6% per year). The burden of AF and the duration of longest episode demonstrated a significant positive correlation to each other but not CHA 2 DS 2 -VASc score. Importantly, although the CHA 2 DS 2 -VASc score was predictive of stroke/TIA, neither burden nor duration was associated with stroke/TIA., Conclusion: Among patients with CIED-detected AF not receiving OAC, the amount of AF (measured by either burden or duration) does not seem to significantly impact stroke risk, whereas CHA 2 DS 2 -VASc score does. These data suggest that among patients with CIED-detected AF, once AF occurs, stroke risk seems to be predominantly driven by underlying risk factors., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Randomized trials inform the use of implantable cardioverter-defibrillators (ICDs) for prevention of sudden cardiac death, yet management of patients considering ICD generator replacement procedures remains largely dependent on clinical judgment. Thus, we performed a systematic review of all studies evaluating outcomes associated with ICD generator replacement. We queried PubMed, Embase, Web of Science, and the Cochrane Database of Systematic Reviews for relevant studies with a prespecified search and adjudication strategy (PROSPERO registration number CRD42018100818) to evaluate outcomes including (1) survival; (2) clinical complications (eg, infection, hematoma); or (3) incidence of ICD therapy. From 1607 unique titles, 37 studies met inclusion criteria, describing outcomes for 238,949 patients. Procedural mortality was rare, but complications including reoperation (median 4.57%; range 0.38%-10.31%), infections (median 2.01%; range 0.03%-9.27%), and hematoma (median 1.22%, range 0.17%-2.53%) were observed in a small fraction of patients. Appropriate ICD therapy after generator replacement was common (median rate 23.03%; range 10.9%-31.4%), with an overall annualized event rate of 8.52% at median duration of follow-up of 32.4 months. Appropriate ICD therapy continued to occur at a significant annual rate even in patients who no longer met implantation criteria (5.27%) and in patients who never previously received ICD therapy (4.87%). This analysis of published observational data regarding ICD generator replacement procedures identifies relatively low risks of procedural complications and clinically meaningful rates of appropriate ICD therapies. These estimates may guide clinical decisions and inform the design of definitive trials., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The performance of Abbott/St. Jude Medical (Sylmar CA) Tendril pacing leads has not been well characterized., Objective: We sought to assess the performance of Tendril leads as compared with that of different pacing leads., Methods: We retrospectively identified patients implanted with the following leads: Tendril leads 1888 TC, 2088 TC, and 1688 TC, Medtronic (Fridely, MN) 4076 CapSureFix Novus, and Boston Scientific (Natick, MA) FINELINE II Sterox Pacing EZ leads (models 4469, 4470, and 4471). The primary end point was the incidence of lead malfunction assessed by Kaplan-Meier analysis., Results: During the study period, 9782 leads were implanted, including 8512 Tendril leads, 731 Medtronic 4076 CapSureFix Novus leads, and 539 FINELINE II leads. A total of 540 leads (5.5%) malfunctioned during a mean follow-up of 3.6 ± 2.9 years. Lead malfunction manifested predominantly as noise and/or low impedance (95%). Lead malfunction rates were significantly higher at 5 years for Tendril vs non-Tendril leads (7.0% vs 2.1%; P < .001). The highest rate of failure at 5 years was seen in the Tendril 1888 TC leads (9.9%), followed by Tendril 1688 (5.7%) and Tendril 2088 (5.2%) leads. In contrast, malfunction rates were significantly lower for the Medtronic 4076 (2.6%) and FINELINE II (1.7%) leads. During follow-up to 10 years, the incidence of lead malfunction for Optim-insulated Tendril leads (models 1888 TC and 2088 TC) was significantly higher than that for the non-Optim-insulated Tendril 1688 TC lead (24.5% vs 7.1%) (P = .008)., Conclusion: Tendril leads appear to have a higher rate of malfunction than do comparator leads. Optim insulation may partly explain the higher failure rate., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Recommendations regarding performance of magnetic resonance imaging (MRI) in non-MRI conditional pacemaker and defibrillator recipients are evolving. Previous studies have suggested low adverse event rates with MRI in nonconditional cardiac implantable electronic device (CIED) recipients, but low power limits optimal characterization of risk., Objective: The purpose of this study was to perform a systematic review and meta-analysis to characterize the clinical risk associated with MRI in CIED recipients in order to improve power., Methods: PubMed and CINAHL indexed articles from 1990 to 2017 were queried. A random effects model was used for meta-analysis of continuous variables. Safety outcomes were evaluated with descriptive statistics., Results: Seventy studies of non-MRI conditional devices undergoing MRI were identified, allowing for analysis of 5099 patients who underwent a total of 5908 MRI studies. Heterogeneity in lead parameter changes was observed within studies, although smaller variances were noted between studies. All lead characteristics and battery voltages showed very small, clinically insignificant changes when assessed as a pooled cohort, although cases of clinically relevant outcomes were also noted (lead failure 3, implantable cardioverter-defibrillator shock 1, electrical reset 94). Electrical resets were found only in older devices. Defibrillator function was unchanged, and inappropriate shocks were avoided with pre-MRI programming changes., Conclusion: This review demonstrated low lead failure and clinical event rates in non-MRI conditional pacemaker and defibrillator recipients undergoing MRI. Observed changes were small and interstudy variance was low, suggesting that the composite event rates offer a reasonable estimate of true effect. The observed adverse events reinforce the need for ongoing vigilance and caution, particularly with older devices., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The decision to abandon or extract superfluous sterile leads is controversial., Objective: The purpose of this study was to compare procedural outcomes and long-term survival of patients with and those without abandoned leads undergoing lead extraction (LE)., Methods: Retrospective review of all patients who had undergone transvenous LE at our institution from January 2007 to May 2016 was performed. Patients were stratified into 2 groups based on the presence (group 1) or absence (group 2) of abandoned leads., Results: Among 774 patients who had undergone LE procedures, 38 (4.9%) had abandoned leads (group 1). Dwell time of the oldest extracted lead was longer in group 1 vs group 2 (7.6 ± 4.9 years vs 5.6 ± 4.4 years; P = .017), as was infection as an indication for LE (76% vs 33%; P <.001). A bailout femoral approach was more commonly required in group 1 than in group 2 (18.4% vs 6%; P = .007). Complete procedural success rates were similar (92.1% in group 1 vs 95.0% in group 2; P = .439), but there was a trend toward lower clinical success in group 1 (92.1% vs 97.4%; P = .088), primarily due to failure to remove all hardware in the setting of infection. Major procedural complication rates were similar (2.6% in group 1 vs 1.2% in group 2; P = .397), as was long-term survival (mean follow-up 2.3 ± 2.2 years)., Conclusion: Abandoned leads at the time of LE were associated with increased procedural complexity, including a higher rate of bailout femoral extraction, and may be associated with lower clinical success. Among appropriately selected patients, consideration should be given to LE instead of abandonment., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Little is known about advance directive (AD) utilization in implantable cardioverter-defibrillator (ICD) recipients., Objective: The purpose of this study was to define the prevalence and predictors of ADs in patients with ICDs., Methods: We identified ICD recipients with ADs at our institution. The primary end point was the prevalence of an AD documented up to 1 year after device implant and the secondary end point was the cumulative prevalence of an AD., Results: Of 2549 patients with ICDs, 701 (27.5%) were followed for at least 1 year after device implant, and of those 701 patients, 164 (23.4%) had ADs documented before or within 1 year of ICD implant. The prevalence of ICD recipients with ADs increased overtime, reaching approximately 10% in the most recent years of analysis. However, only 1 AD specifically addressed the ICD as part of end-of-life decision making. In multivariable analysis, more recent year of device implant and prior cardiovascular hospitalization were positively associated with having an AD within 1 year of implant. The cumulative prevalence of an AD at any time after implant reached about 30%, with more recent implant year, prior cardiovascular hospitalization, and palliative care consultation positively associated with the presence of an AD and black race associated with a lower cumulative prevalence., Conclusion: In a tertiary academic medical center, most patients with ICDs still do not have ADs, and even when they do, the ICDs are rarely addressed as part of the directive. Several predictors of ADs emerged, which may provide opportunities to improve utilization of ADs in ICD recipients., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Extraction of pacemaker and defibrillator leads in young adults may be technically challenging because of more extensive fibrosis and calcification in this patient population., Objective: The purpose of this study was to examine outcomes of lead extraction (LE) in young adults at our institution., Methods: We retrospectively identified all patients who underwent LE at our institution between January 1, 2007, and May 31, 2016. Patients were divided by age into 2 groups: <40 years (group 1, n = 84) or ≥40 years (group 2, n = 690). Outcomes were determined by medical records review., Results: Patients in group 2 had a higher overall average number of leads extracted per procedure compared to group 1 (1.64 ± 0.80 vs 1.45 ± 0.64; P <.001). Lead dwell time was similar in the 2 groups (5.7 ± 5 years vs 5.6 ± 4.3 years; P = .95). The younger cohort tended to require femoral extraction techniques more frequently (9.5% vs 4.4%; P = .055). Extraction procedural success (group 1: 94.1%, group 2: 94.9%; P = .792), major complications (group 1: 0%, group 2: 1.3%; P = 1), and periprocedural mortality (group 1: 0%, group 2: 0.86%; P = 1) were similar in the 2 groups., Conclusion: LE can be performed safely and effectively in young adults. Despite the lower number of leads extracted per procedure and the similar lead dwell time, younger adults more frequently required the use of femoral extraction tools, thus highlighting the importance of performing these procedures in centers with advanced expertise in extraction techniques., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Lead extraction (LE) infrequently requires the use of the "bailout" femoral approach. Predictors and outcomes of femoral extraction are not well characterized., Objective: The aim of this study was to determine the predictors of need for femoral LE and its outcomes., Methods: Consecutive patients who underwent LE at our centers were identified. Baseline demographic characteristics, procedural outcomes, and clinical outcomes were ascertained by medical record review. Patients were stratified into 2 groups on the basis of the need for femoral extraction., Results: A total of 1080 patients underwent LE, of whom 50 (4.63%) required femoral extraction. Patients requiring femoral extraction were more likely to have leads with longer dwell time (9.5 ± 6.0 years vs 5.7 ± 4.3 years; P < .001), to have more leads extracted per procedure (2.0 ± 1.0 vs 1.7 ± 0.9; P = .003), and to have infection as an indication for extraction (72% vs 37.2%; P < .001). Procedural and clinical success was lower in the femoral extraction group than in the nonfemoral group (58% and 76% vs 94.7% and 97.9 %, respectively; P < .001). Major periprocedural complications (0% vs 1.3%; P = 1.0) and periprocedural mortality (0% vs 0.8%; P = 1.0) were similar between the 2 groups., Conclusion: In this study, femoral extraction was needed in ~5% of LEs. Longer lead dwell time, higher number of leads extracted per procedure, and the presence of infection predicted the need for femoral extraction. Procedural success of femoral extraction was low, highlighting the fact that this approach is mostly used as a bailout strategy and thus selects for more challenging cases., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The Sprint Fidelis (SF) and the Riata (RT) implantable cardioverter-defibrillator leads have been recalled for premature failure., Objective: Data on SF and RT extractions are limited; therefore, we performed a pooled analysis to compare the safety and efficacy of lead extraction for the SF and RT lead families., Methods: We retrospectively reviewed consecutive patients undergoing transvenous extraction of SF and RT leads at Emory University and the University of Pittsburgh Medical Center from January 2007 to October 2013. Patients were placed into 2 groups based on the presence of an SF or RT lead. The primary endpoint was a major procedural complication, defined as death, need for urgent cardiac surgery, and hemopericardium or hemothorax that required an intervention., Results: A total of 462 patients underwent extraction of recalled leads (SF, n = 360; RT, n = 102). The mean number of leads extracted in the RT group was higher than in the SF group (1.8 ± 0.9 vs 1.3 ± 0.7, P < .001), and there was a longer implantation time in the RT group (5.5 ± 2.5 vs 4.3 ± 2.0 years, P < .001). Complete procedural success was higher in the SF group (99.4% vs 96.1%, P =.024). Clinical success was similar (SF 99.4% vs RT 97.1%, P = .075). There were 6 major procedural complications in the entire cohort (1.3%). The rate of major complications was not different between the SF and RT groups (SF 1.1% vs RT 2.0%, P = .618). Total mortality was 0.65%, with no difference between the groups, Conclusion: Our data from 2 high-volume centers suggest that extraction of SF and RT leads is associated with excellent clinical success and a similar rate of major procedural complications., (Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Repolarization alternans (RA), a pattern of ventricular repolarization that repeats on an every other beat basis, has been closely linked with the substrate associated with ventricular tachycardia/ventricular fibrillation., Objective: To evaluate a novel method to suppress RA., Methods: We have developed a novel method to dynamically (on R-wave detection) trigger pacing pulses during the absolute refractory period. We have tested the ability of this method to control RA in a structurally normal swine heart in vivo., Results: RA induced by triggered pacing can be measured from both intracardiac and body surface leads and the amplitude of R-wave triggered pacing-induced alternans can be locally modulated by varying the amplitude and width of the pacing pulse. We have estimated that to induce a 1 μV change in alternans voltage on the body surface, coronary sinus, and left ventricle leads, a triggered pacing pulse delivered in the right ventricle of 0.04±0.02, 0.05±0.025, and 0.06±0.033 μC, respectively, is required. Similarly, to induce a 1 unit change in Kscore (ratio of alternans peak to noise), a pacing stimulus of 0.93±0.73, 0.32±0.29, and 0.33±0.37 μC, respectively, is required. We have been able to demonstrate that RA can be suppressed by R-wave triggered pacing from a site that is within or across ventricles. Lastly, we have demonstrated that the proposed method can be used to suppress spontaneously occurring alternans in the diseased heart., Conclusion: We have developed a novel method to suppress RA in vivo., (Copyright © 2013. Published by Elsevier Inc.)

Background: The early repolarization pattern (ERP) is common and associated with risk of sudden cardiac death. ERP is heritable, and mutations have been described in syndromatic cases., Objective: To conduct a meta-analysis of genome-wide association studies to identify common genetic variants influencing ERP., Methods: We ascertained ERP on the basis of electrocardiograms in 3 large community-based cohorts from Europe and the United States: the Framingham Heart Study, the Health 2000 Study, and the KORA F4 Study. We analyzed genome-wide association studies in participants with and without ERP by logistic regression assuming an additive genetic model and meta-analyzed individual cohort results. We then sought to strengthen support for findings that reached P ≤ 1 × 10(-5) in independent individuals by direct genotyping or in-silico analysis of genome-wide data. We meta-analyzed the results from both stages., Results: Of 7482 individuals in the discovery stage, 452 showed ERP (ERP positive: mean age 46.9 ± 8.9 years, 30.3% women; ERP negative: 47.5 ± 9.4 years, 54.2% women). After meta-analysis, 8 single nucleotide polymorphisms reached P ≤ 1 × 10(-5): The most significant finding was intergenic rs11653989 (odds ratio 0.47; 95% confidence interval 0.36-0.61; P = 6.9 × 10(-9)). The most biologically relevant finding was intronic to KCND3: rs17029069 (odds ratio 1.46; 95% confidence interval 1.25-1.69; P = 8.5 × 10(-7)). In the replication step (7151 individuals), none of the 8 variants replicated, and combined meta-analysis results failed to reach genome-wide significance., Conclusions: In a genome-wide association study, we were not able to reliably identify genetic variants predisposing to ERP, presumably due to insufficient statistical power and phenotype heterogeneity. The reported heritability of ERP warrants continued investigation in larger well-phenotyped populations., (Copyright © 2012 Heart Rhythm Society. All rights reserved.)

Background: T-wave alternans (TWA) has been associated with increased vulnerability to ventricular tachyarrhythmias and sudden cardiac death. However, both random (white) noise and (patho)physiologic processes (ie, premature ventricular contractions and heart and respiration rates) may hamper TWA estimation and therefore lessen its clinical utility for risk stratification., Objective: To investigate the effect of random noise and certain (patho)physiologic processes on the estimation of TWA by using the fast Fourier transform method and to develop methods to overcome these potential sources of error., Methods: We used a combination of human electrocardiogram data and computer simulations to assess the effects of a premature ventricular contraction and random and colored noise on the accuracy of TWA estimation., Results: We quantitatively demonstrate that replacing a "bad" beat with an odd/even median beat is a more accurate approach than replacing it with the overall average or the overall median beat. We also show that phase resetting may have a significant effect on alternans estimation and that estimation of alternans by using frequencies >0.4922 cycles/beat in a 128-point fast Fourier transform provides the most accurate approach for estimating the alternans when phase resetting is likely to occur. In addition, our data demonstrate that the number of indeterminate TWA tests due to high levels of noise can be reduced when the alternans voltage exceeds a new higher threshold. Furthermore, the amplitude of random noise has a significant effect on alternans estimation and the alternans voltage threshold should be adjusted for noise levels >1.8 μV. Finally, we quantitatively demonstrate that colored noise may lead to a false-positive or a false-negative result. We propose methods to estimate the effect of these (patho)physiologic processes on the alternans estimation in order to determine whether a TWA test is likely to be a true positive or a true negative., Conclusion: This study introduces novel methods to overcome potential sources of error in the estimation of TWA. These methods may improve the utility of TWA either for ambulatory monitoring or for clinical risk stratification for ventricular arrhythmias and sudden cardiac death., (Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The optimal pacing site for cardiac resynchronization therapy (CRT) is along the left ventricle (LV) lateral or posterolateral wall. However, little is known about the impact of segmental pacing site on outcomes., Objective: We assessed the impact of segmental LV lead position on CRT outcomes., Methods: Patients (n = 115) undergoing CRT were followed prospectively. Segmental LV lead position along the longitudinal axis (apical, midventricle, or basal) was determined retrospectively by examining coronary sinus (CS) venograms and chest X-rays. The primary outcome was a combined endpoint of heart failure hospitalization, cardiac transplantation, or all-cause mortality. Secondary outcomes included change in New York Heart Association (NYHA) functional class and degree of LV reverse remodeling., Results: Patients were divided into two groups based on LV lead position: apical (n = 25) and basal/midventricle (n = 90). The apical group was older (72.9 +/- 8.9 vs. 66.5 +/- 13.3 years; P = .010) and more likely to have ischemic cardiomyopathy (77% vs. 52%, P <.001). During a mean follow-up of 15.1 +/- 9.0 months, event-free survival was significantly lower in the apical group: 52% vs. 79%, hazard ratio [HR] 2.7 (95% confidence interval [CI] 1.5-5.5, P = .006). The adverse impact of apical lead placement remained significant after adjusting for clinical covariates: HR 2.3 (95% CI 1.1-4.8, P = .03). The apical group also experienced less improvement in NYHA functional class and less LV reverse remodeling., Conclusions: Apical LV lead placement is associated with worse CRT outcomes. Preferential positioning of LV leads in the basal/midventricle segments may improve outcomes., (Copyright 2010. Published by Elsevier Inc.)