Angel R Leon

Emory University, Atlanta, Georgia, United States

Are you Angel R Leon?

Claim your profile

Publications (116)916.42 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: T wave oversensing (TWOS) is a major drawback of the subcutaneous implantable cardioverter defibrillator (S-ICD). Data on predictors of TWOS in S-ICD recipients are limited.
    No preview · Article · Feb 2016 · Journal of Arrhythmia
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although implantable cardioverter-defibrillators (ICDs) are frequently viewed as a lifelong commitment in that patients are routinely scheduled for generator exchange (GE) at end of battery life, several considerations should prompt a reevaluation of risks and benefits before GE. Compared with initial ICD implant, patients receiving replacement devices are older, and have more comorbidities and shorter life expectancy, all of which may limit the benefit of ICD therapy following GE. Additionally, GE is associated with significant complications, including infection, which may increase the risk of mortality. In this paper, we review recent data regarding opportunities for risk stratification before GE, with a particular focus on those with improved left ventricular function and those who have not experienced ICD therapies during the first battery life. We also provide a broader perspective on ICD therapy, focusing on how decisions regarding GE may affect goals of care at the end of life.
    No preview · Article · Feb 2016 · Journal of the American College of Cardiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background Novel atrial fibrillation (AF) ablation tools have been designed to facilitate “single-shot” pulmonary vein (PV) isolation using multi-electrode or balloon-based catheters. However, in contrast to point-by-point radiofrequency ablation, these tools may be more dependent on suitable PV anatomy to achieve circumferential PV isolation. Methods Three hundred and twenty-two patients underwent gadolinium-enhanced cardiac magnetic resonance angiography to delineate PV anatomy prior to initial AF ablation. Long (a) and short (b) axis measurements of the PV orifice were used to calculate the eccentricity index of the PV ostium. Results Long axis dimensions of the left superior PV were 18.2 ± 3.3 mm, left inferior PV 17.7 ± 3.9 mm, right superior PV (RSPV) 20.4 ± 4.3, and right inferior PV 18.7 ± 4.7 mm. The long axis dimension of the RSPV was significantly larger than other PVs (p < 0.001). Forty-two patients (13 %) had at least one PV with a long axis dimension >25 mm and 16 patients (5 %) had at least one PV with a long axis dimension >28 mm. Left-sided PV ostia were significantly more ellipse-shaped than the right-sided PVs, which tended to be more spherical. A significant positive correlation was noted between increasing PV size and increased orifice eccentricity. Conclusions In this large cohort undergoing initial AF ablation, over 10 % of patients had at least one standard PV with a dimension >25 mm. Additionally, significant differences were noted between left- and right-sided veins with regard to orifice eccentricity. These findings have implications for the design of AF ablation tools and may account for differential isolation rates between PVs noted in some recent studies of novel ablation technologies.
    No preview · Article · Jan 2016 · Journal of Interventional Cardiac Electrophysiology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The subcutaneous implantable cardioverter defibrillator (S-ICD) was introduced to overcome complications related to transvenous leads. Adoption of the S-ICD requires implanters to learn a new implantation technique. The aim of this study was to assess the learning curve for S-ICD implanters with respect to implant-related complications, procedure time, and inappropriate shocks (IASs). In a pooled cohort from two clinical S-ICD databases, the IDE Trial and the EFFORTLESS Registry, complications, IASs at 180 days follow-up and implant procedure duration were assessed. Patients were grouped in quartiles based on experience of the implanter and Kaplan-Meier estimates of complication and IAS rates were calculated. A total of 882 patients implanted in 61 centres by 107 implanters with a median of 4 implants (IQR 1,8) were analysed. There were a total of 59 patients with complications and 48 patients with IAS. The complication rate decreased significantly from 9.8% in Quartile 1 (least experience) to 5.4% in Quartile 4 (most experience) (P = 0.02) and non-significantly for IAS from 7.9 to 4.8% (P = 0.10). Multivariable analysis demonstrated a hazard ratio of 0.78 (P = 0.045) for complications and 1.01 (P = 0.958) for IAS. Dual-zone programming increased with experience of the individual implanter (P < 0.001), which reduced IAS significantly in the multivariable model (HR 0.44, P = 0.01). Procedure time decreased from 75 to 65 min (P < 0.001). The complication rate and procedure time stabilized after Quartile 2 (>13 implants). There is a short and significant learning curve associated with physicians adopting the S-ICD. Performance stabilizes after 13 implants. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Cardiology.
    Full-text · Article · Aug 2015 · Europace
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We sought to determine whether peri-infarct pacing prevents left ventricular (LV) remodelling and improves functional and clinical outcomes in patients with large first myocardial infarction (MI). A total of 126 patients at 27 international sites within 10 days of onset of anterior or non-anterior MI with creatine phosphokinase >3000 U/L and QRS duration ≤120 ms were randomized 1:1:1 to dual-site biventricular pacing vs. single-site LV only pacing vs. non-implanted control. The primary endpoint was the echocardiographic core laboratory-assessed change in LV end-diastolic volume (ΔLVEDV) from baseline to 18 months between the pooled pacing therapy groups and the control group. ΔLVEDV increased by 15.3 ± 28.6 mL in the control group and by 16.7 ± 30.5 mL in the pooled pacing groups during follow-up (adjusted mean difference (95% CI) = 0.6 (-12.3, 13.5) mL, P = 0.92). There were also no significant between-group differences in the change in LV end-systolic volume or ejection fraction over time. Quality of life, as assessed by the Minnesota Living with Heart Failure (HF) and European Quality of Life-5 Dimension questionnaires and New York Heart Association class, was also similar between groups during 18-month follow-up. Six-minute walk distance improved during follow-up to an equal degree between groups, and there were no significant differences in the 18-month rates of death or HF hospitalization between the pooled pacing therapy vs. control groups (17.4 vs. 21.7% respectively, P = 0.59). In the present multicentre, randomized trial, peri-infarct pacing did not prevent LV remodelling or improve functional or clinical outcomes during 18-month follow-up in patients with large first MI. NCT01213251. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.
    Preview · Article · Aug 2015 · European Heart Journal
  • [Show abstract] [Hide abstract]
    ABSTRACT: Little data exists on long-term outcomes following extraction of implantable cardioverter-defibrillator (ICD) leads, particularly for non-infectious indications. We sought to identify predictors of long-term survival after ICD lead extraction. We retrospectively reviewed ICD lead extractions at our institution (n = 508). Procedural outcomes and long-term survival were ascertained by medical records review. Indication for lead extraction was infection in 32.5% and lead failure in 61.8%. Mean dwell time of the oldest extracted lead was 5.1 ± 5.9 years. Complete procedural success was achieved in 96.5% of cases. Major procedure related complications occurred in 1.6% with 6 peri-procedural deaths. During a mean follow-up of 866 ± 798 days, survival was significantly worse among patients with infection as the indication for extraction. At one year after extraction, survival among those with infection was 88.2%, compared to 95.0% in the lead failure cohort (p < 0.001). Procedural failure was a significant predictor of long-term mortality, even after excluding peri-procedural deaths. In multivariate models, the presence of chronic kidney disease, increased number of leads requiring extraction, lower ejection fraction and procedural failure were predictors of mortality. Despite high rates of procedural success, infectious indication for ICD lead extraction is associated with increased long-term mortality. In contrast, among patients undergoing extraction for lead failure, long-term survival was excellent. The presence of procedural failure was a significant predictor of long-term mortality. Further studies will be necessary to better understand the mechanisms by which procedural failure may adversely impact long-term outcomes. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    No preview · Article · Aug 2015 · Pacing and Clinical Electrophysiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: IntroductionSt. Jude Riata/Riata ST defibrillator leads were recalled by the FDA in 2011 for an increased rate of failure. More than 227,000 leads were implanted and at least 79,000 patients still have active Riata leads. Studies have examined clinical predictors of lead failure in Riata leads, but none have addressed the effect of ICD generator exchange on lead failure. The purpose of this study is to assess the effect of ICD generator exchange on the rate of electrical failure in the Riata lead at 1 year.MethodsA retrospective chart review was conducted in patients who underwent implantation of a Riata/Riata ST lead at one center. Patients with a functioning Riata lead (with/with externalized conductor) at the time of ICD exchange were compared to controls with Riata leads implanted for a comparable amount of time who did not undergo generator replacement.ResultsRiata leads were implanted in 1,042 patients prior to the recall and153 of these patients underwent generator exchange without lead replacement. Conductor externalization was noted in 21.5% of Riata leads in the ICD exchange cohort, which was not different from the control group, 19.2% (p = 0.32). Two leads failed in the first year after generator replacement (1.5%) which did not significantly differ from the control group (2.0%), (p = 0.57). At change-out 54% received a commanded shock (18.6 ± 0.9 J) that did not result in any change in the high voltage lead impedance (46.1 ± 1.1 ohms).Conclusions Conductor externalization was seen frequently in our cohort of patients. ICD generator exchange did not accelerate the rate of Riata lead failure at 1 year. Although, both the control and the change-out cohorts failed at a rate much greater than nonrecalled leads, generator exchange did not appear to add to the problem.This article is protected by copyright. All rights reserved
    No preview · Article · Aug 2015 · Pacing and Clinical Electrophysiology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Despite marked benefits in many heart failure patients, a considerable proportion of patients treated with cardiac resynchronization therapy (CRT) fail to respond appropriately. Recently, a "U-shaped" (type II) wall motion pattern identified by cardiovascular magnetic resonance (CMR) has been associated with improved CRT response compared to a homogenous (type I) wall motion pattern. There is also evidence that a left ventricular (LV) lead localized to the latest contracting LV site predicts superior response, compared to an LV lead localized remotely from the latest contracting LV site. We prospectively evaluated patients undergoing CRT with pre-procedural CMR to determine the presence of type I and type II wall motion patterns and pre-procedural echocardiography to determine end systolic volume (ESV). We assessed the final LV lead position on post-procedural fluoroscopic images to determine whether the lead was positioned concordant to or remote from the latest contracting LV site. CRT response was defined as a ≥ 15 % reduction in ESV on a 6 month follow-up echocardiogram. The study included 33 patients meeting conventional indications for CRT with a mean New York Heart Association class of 2.8 ± 0.4 and mean LV ejection fraction of 28 ± 9 %. Overall, 55 % of patients were echocardiographic responders by ESV criteria. Patients with both a type II pattern and an LV lead concordant to the latest contracting site (T2CL) had a response rate of 92 %, compared to a response rate of 33 % for those without T2CL (p = 0.003). T2CL was the only independent predictor of response on multivariate analysis (odds ratio 18, 95 % confidence interval 1.6-206; p = 0.018). T2CL resulted in significant incremental improvement in prediction of echocardiographic response (increase in the area under the receiver operator curve from 0.69 to 0.84; p = 0.038). The presence of a type II wall motion pattern on CMR and a concordant LV lead predicts superior CRT response. Improving patient selection by evaluating wall motion pattern and targeting LV lead placement may ultimately improve the response rate to CRT.
    Full-text · Article · Jul 2015 · Journal of Cardiovascular Magnetic Resonance
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Sprint Fidelis (SF) and the Riata (RT) implantable cardioverter-defibrillator leads have been recalled for premature failure. 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. 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. 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.
    No preview · Article · Jun 2015 · Heart rhythm: the official journal of the Heart Rhythm Society
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although the subcutaneous ICD (S-ICD(®) ) is an attractive alternative in patients with end-stage renal disease (ESRD), data on S-ICD outcomes in dialysis patients is lacking. Patients with cardiomyopathy undergoing S-ICD implantation in our center were stratified by need for chronic dialysis at the time of implant. The primary endpoint was incidence of death, heart failure hospitalization or appropriate S-ICD shocks, and secondary endpoints were incidence of inappropriate shocks or implant related complications requiring surgical re-intervention. Mean follow-up was longer in the non-dialysis cohort (514 ± 495 vs. 227 ± 233 days, p = 0.006), so all endpoints were analyzed using time-dependent comparisons and reported as annual event rates. Out of 79 S-ICD implants included in this analysis, 27 patients were on dialysis. Dialysis patients were older and more likely to be diabetic. Mean ejection fraction across the entire cohort was 26.9% without significant difference between dialysis and non-dialysis groups. Although not significant, the incidence of the primary endpoint was higher in the dialysis cohort (23.8%/year vs. 10.9%/year, p = 0.317), driven primarily by a higher rate of appropriate shocks. The rate of inappropriate shocks was similar between groups (dialysis 6.0%/year vs. non-dialysis 6.8%/year, p = 0.509). No patients in the dialysis cohort had complications requiring surgical re-intervention versus 6 patients in the non-dialysis cohort (p = 0.086). Our data suggest that S-ICD implantation in dialysis patients is not associated with an excess risk of implant related complications or inappropriate shocks. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    No preview · Article · May 2015 · Journal of Cardiovascular Electrophysiology

  • No preview · Conference Paper · May 2015

  • No preview · Conference Paper · May 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The entirely subcutaneous implantable cardioverter-defibrillator (S-ICD) is the first implantable defibrillator that avoids placing electrodes in or around the heart. Two large prospective studies (IDE [S-ICD System IDE Clinical Investigation] and EFFORTLESS [Boston Scientific Post Market S-ICD Registry]) have reported 6-month to 1-year data on the S-ICD.
    Full-text · Article · Apr 2015 · Journal of the American College of Cardiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to retrospectively investigate whether performing surgical atrial fibrillation (AF) ablation in conjunction with cardiac surgery (CS) increases the risk for postoperative permanent pacemaker (PPM) requirement. The 30-day risk for PPM requirement was analyzed in consecutive patients who underwent CS from January 2007 to August 27, 2013. Patients were divided into 3 groups: (1) those who underwent AF ablation concomitant with CS (AF ABL), (2) patients with any history of AF who underwent surgery who did not undergo ablation (AF NO ABL), and (3) those with no histories of AF who underwent surgery (NO AF). Logistic regression analysis was performed adjusting for age, gender, and surgery type. Of 13,453 CS patients, 353 (3%) were in the AF ABL group, 1,701 (12%) in the AF NO ABL group, and 11,399 (85%) in the NO AF group. A total of 7,651 patients (57%) underwent coronary artery bypass grafting, 4,384 (33%) underwent valve surgery, and 1,418 (10%) underwent coronary artery bypass grafting and valve surgery. The overall PPM risk was 1.6% (212 of 13,453); risk was 5.7% (20 of 353) in the AF ABL group, 3.1% (53 of 1,701) in the AF NO ABL group, and 1.2% (139 of 11,399) in the NO AF group. The unadjusted and adjusted odds of PPM were higher in the AF ABL and AF NO ABL groups than in the NO AF group (adjusted odds ratio [OR] 2.7, 95% confidence interval [CI] 1.7 to 4.4, and adjusted OR 1.7, 95% CI 1.2 to 2.4, respectively). The unadjusted OR comparing the AF ABL group and the AF NO ABL group was significant (unadjusted OR 1.9, 95% CI 1.9 to 3.2); however, the OR adjusted for surgery type, age, and gender showed a trend toward significance (adjusted OR 1.6, 95% CI 0.9 to 2.7). In conclusion, in this large cohort of patients who underwent CS, surgical AF ablation appeared to carry an increased risk for postoperative PPM implantation. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Apr 2015 · The American journal of cardiology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Despite considerable improvements in the medical management of patients with myocardial infarction (MI), patients with large MI still have substantial risk to develop heart failure. In the early post MI setting, implantable cardioverter defibrillators have reduced arrhythmic deaths but have no impact on overall mortality. Hence, additional interventions are required to further reduce the overall morbidity and mortality of patients with large MI. The pacing remodeling prevention therapy (PRomPT) trial is designed to study the effects of peri-infarct pacing in preventing adverse post-MI remodeling. Up to 250 subjects with a peak creatine phosphokinase (CPK) > 3000 U/L (or a troponin T (TnT) > 10 mcg/L) at time of MI will be randomized to either dual-site or single-site biventricular pacing with the LV lead implanted in a peri-infarct region or a non-implanted control. Those randomized to a device will be blinded to the pacing mode, however randomization to a device or control cannot be blinded. Subjects randomized to pacing will have the device implanted within 10 days of MI. The primary objective is to assess the change in left ventricular end diastolic volume (LVEDV) from baseline to 18 months. Secondary objectives are to assess changes in clinical and mechanistic parameters between the groups, including rates of hospitalization for heart failure and cardiovascular events, the incidence of sudden cardiac death and all-cause mortality, NYHA functional class, 6 minute walking distance, and quality of life CONCLUSIONS: The PRomPT trial will provide important evidence regarding the potential of peri-infarct pacing to interrupt adverse remodeling in patients with large MI. Copyright © 2015 Elsevier Inc. All rights reserved.
    Full-text · Article · Mar 2015 · Journal of cardiac failure

  • No preview · Article · Mar 2015 · Journal of the American College of Cardiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND Lead malfunction is an important cause of morbidity and mortality in patients with an implantable cardioverterdefibrillator (ICD). We have shown that the failure of recalled highvoltage Leads significantly increases after ICD generator replacement. However, generator replacement has not been recognized as a predictor of lead failure in general. OBJECTIVE The purpose of this study is to assess the effect of ICD generator exchange on the rate of ICD lead alerts. METHODS A time-dependent Cox proportional hazards model was used to analyze a database of remotely monitored ICDs. The model assessed the impact of generator exchange on the rate of lead alerts after ICD generator replacement. RESULTS The analysis included 60,219 patients followed for 37 t 19 months. The 5-year Lead survival was 99.3% (95% confidence interval 99.2%-99.4%). Of 60,219 patients, 7458 patients (12.9%) underwent ICD generator exchange without Lead replacement. After generator replacement, the rate of lead alerts was more than 5-fold higher than in controls with leads of the same age without generator replacement (hazard ratio 5.19; 95% confidence interval 3.45-7.84). A large number of lead alerted within 3 months of generator replacement. Lead alerts were more common in patients with single- vs dual-chamber ICDs and in younger patients. Sex was not associated with Lead alerts. CONCLUSION Routine generator replacement is associated with a 5-fold higher risk of lead alert compared to age-matched leads without generator replacement. This suggests the need for intense surveillance after generator replacement and the development of techniques to minimize the risk of lead damage during generator replacement.
    No preview · Article · Jun 2014 · Heart rhythm: the official journal of the Heart Rhythm Society
  • Source
    Sally Aziz · Angel R. Leon · Mikhael F. El-Chami
    [Show abstract] [Hide abstract]
    ABSTRACT: The recently commercially available Subcutaneous Implantable Cardioverter-Defibrillator (S-ICD) utilizes a completely subcutaneous electrode configuration to treat potentially lethal ventricular tachyarrhythmia. Clinical trials have proven its effectiveness in detecting and treating ventricular fibrillation and tachycardia. The S-ICD offers the advantage of eliminating the need for intravenous and intracardiac leads and their associated risks and shortcomings. However, its major disadvantage is its inability to provide bradycardia rate support and anti-tachycardia pacing to terminate ventricular tachycardia. This article reviews the S-ICD clinical trials and the advantages and disadvantages of this novel technology to help the physician identify its role and select candidates that will benefit from this device.
    Preview · Article · Apr 2014 · Journal of the American College of Cardiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: The subcutaneous ICD system (S-ICD) uses a novel detection algorithm previously shown to discriminate induced tachyarrhythmias (ventricular vs supraventricular) effectively. To evaluate the role of the S-ICD discrimination algorithm in reducing the incidence of spontaneous inappropriate shocks. There were 314 subjects who underwent implantation with an S-ICD System as part of the S-ICD Clinical Investigation (IDE Trial). Subjects were grouped according to programming at discharge, to either a single shock zone or two shock zones, with a discrimination algorithm in the lower rate zone. This cohort had 226 (72%) subjects with dual zone programming and 88 (28%) subjects with single zone programming. Over a mean follow-up period of 661 ± 174 days, inappropriate shocks occurred in 23 subjects from the dual zone sub-group (10.2%) and 23 subjects from the single zone sub-group (26.1%; P < 0.001), with 2 year inappropriate shock free rates of 89.7% vs 73.6%; respectively (HR=0.38; P = 0.001). Freedom from appropriate shocks did not differ between sub-groups (92.2% vs 90.3%; HR=0.82; P=0.64). Moreover, mean time to appropriate therapy did not differ between sub-groups and there was only one episode of arrhythmic syncope in the cohort. The addition of a second shock zone with an active discrimination algorithm was strongly associated with a reduction in inappropriate shocks with the S-ICD system and did not result in prolongation of detection times or increased syncope. These data support the use of dual zone programming as a standard setting for S-ICD patients.
    No preview · Article · Apr 2014 · Heart rhythm: the official journal of the Heart Rhythm Society
  • Source

    Full-text · Article · Apr 2014 · Journal of the American College of Cardiology

Publication Stats

10k Citations
916.42 Total Impact Points

Institutions

  • 1993-2015
    • Emory University
      • • School of Medicine
      • • Division of Cardiology
      Atlanta, Georgia, United States
  • 2009
    • Boston Scientific
      Boston, Massachusetts, United States
  • 2008
    • Emory Hospitals
      Atlanta, Georgia, United States
  • 1992-1994
    • Concordia University–Ann Arbor
      Ann Arbor, Michigan, United States