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BACKGROUND: Cardiac resynchronisation therapy (CRT) improves outcomes in selected patients with heart failure and left ventricular dysfunction. One mechanism of benefit is believed to be favourable ventricular remodelling. Whether CRT also decreases the frequency of ventricular arrhythmias and risk of sudden death is unknown. OBJECTIVE: To determine the effect of CRT on frequency of ventricular arrhythmias and appropriate ICD therapies. DESIGN: Retrospective cohort study. SETTING: Single-centre, tertiary care facility (Mayo Clinic). PATIENTS: 52 patients (46 male), aged 70 (SD 10) years, who underwent upgrade from an implantable cardioverter defibrillator (ICD) to a CRT-defibrillator were included. INTERVENTIONS: Upgrade of ICD to CRT-defibrillator. MAIN OUTCOME MEASURES: Frequency of ventricular arrhythmias prior to and following upgrade to CRT device. RESULTS: Ejection fraction increased from 22% (SD 8%) to 27% (SD 11%) following CRT. However, the frequency of non-sustained ventricular arrhythmias, sustained ventricular arrhythmias, and ventricular fibrillation was not significantly changed prior to and following CRT (2.38 (SD 9.78) vs 58.51 (SD 412.73) per patient per month, p = 0.66; 0.07 (SD 0.17) vs 0.16 (SD 0.52), p = 0.70; 0.05 (SD 0.12) vs 0.25 (SD 1.40), p = 0.12). CONCLUSIONS: CRT is not associated with a decrease in the frequency of ventricular arrhythmia or appropriate device therapy. Thus, use of CRT alone is not beneficial in decreasing the frequency of ventricular arrhythmias or the risk of appropriate ICD therapies. [ABSTRACT FROM AUTHOR]

Introduction: We observed a change in the atrial activation sequence during radiofrequency (RF) energy application in patients undergoing left accessory pathway (AP) ablation. This occurred without damage to the AP and in the absence of a second AP or alternative arrhythmia mechanism. We hypothesized that block in a left atrial 'isthmus' of tissue between the mitral annulus and a left inferior pulmonary vein was responsible for these findings. Methods and Results: Electrophysiologic studies of 159 patients who underwent RF ablation of a left free-wall AP from 1995 to 1999 were reviewed. All studies with intra-atrial conduction block resulting from RF energy delivery were identified. Fluoroscopic catheter positions were reviewed. Intra-atrial conduction block was observed following RF delivery in 11 cases (6.9%). This was evidenced by a sudden change in retrograde left atrial activation sequence despite persistent and unaffected pathway conduction. In six patients, reversal of eccentric atrial excitation during orthodromic reciprocating tachycardia falsely suggested the presence of a second (septal) AP. A multipolar coronary sinus catheter in two patients directly demonstrated conduction block along the mitral annulus during tachycardia. Conclusion: An isthmus of conductive tissue is present in the low lateral left atrium of some individuals. Awareness of this structure may avoid misinterpretation of the electrogram during left AP ablation and may be useful in future therapies of atypical atrial flutter and fibrillation. [ABSTRACT FROM AUTHOR]

Background: The United States (US) Expanded Access Program (EAP) to coronavirus disease 2019 (COVID-19) convalescent plasma was initiated in response to the rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19. While randomized clinical trials were in various stages of development and enrollment, there was an urgent need for widespread access to potential therapeutic agents. The objective of this study is to report on the demographic, geographical, and chronological characteristics of patients in the EAP, and key safety metrics following transfusion of COVID-19 convalescent plasma., Methods and Findings: Mayo Clinic served as the central institutional review board for all participating facilities, and any US physician could participate as a local physician-principal investigator. Eligible patients were hospitalized, were aged 18 years or older, and had-or were at risk of progression to-severe or life-threatening COVID-19; eligible patients were enrolled through the EAP central website. Blood collection facilities rapidly implemented programs to collect convalescent plasma for hospitalized patients with COVID-19. Demographic and clinical characteristics of all enrolled patients in the EAP were summarized. Temporal patterns in access to COVID-19 convalescent plasma were investigated by comparing daily and weekly changes in EAP enrollment in response to changes in infection rate at the state level. Geographical analyses on access to convalescent plasma included assessing EAP enrollment in all national hospital referral regions, as well as assessing enrollment in metropolitan areas and less populated areas that did not have access to COVID-19 clinical trials. From April 3 to August 23, 2020, 105,717 hospitalized patients with severe or life-threatening COVID-19 were enrolled in the EAP. The majority of patients were 60 years of age or older (57.8%), were male (58.4%), and had overweight or obesity (83.8%). There was substantial inclusion of minorities and underserved populations: 46.4% of patients were of a race other than white, and 37.2% of patients were of Hispanic ethnicity. Chronologically and geographically, increases in the number of both enrollments and transfusions in the EAP closely followed confirmed infections across all 50 states. Nearly all national hospital referral regions enrolled and transfused patients in the EAP, including both in metropolitan and in less populated areas. The incidence of serious adverse events was objectively low (<1%), and the overall crude 30-day mortality rate was 25.2% (95% CI, 25.0% to 25.5%). This registry study was limited by the observational and pragmatic study design that did not include a control or comparator group; thus, the data should not be used to infer definitive treatment effects., Conclusions: These results suggest that the EAP provided widespread access to COVID-19 convalescent plasma in all 50 states, including for underserved racial and ethnic minority populations. The study design of the EAP may serve as a model for future efforts when broad access to a treatment is needed in response to an emerging infectious disease., Trial Registration: ClinicalTrials.gov NCT#: NCT04338360., Competing Interests: The authors have declared that no competing interests exist.

Successful therapeutics and vaccines for coronavirus disease 2019 (COVID-19) have harnessed the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Evidence that SARS-CoV-2 exists as locally evolving variants suggests that immunological differences may impact the effectiveness of antibody-based treatments such as convalescent plasma and vaccines. Considering that near-sourced convalescent plasma likely reflects the antigenic composition of local viral strains, we hypothesize that convalescent plasma has a higher efficacy, as defined by death within 30 days of transfusion, when the convalescent plasma donor and treated patient were in close geographic proximity. Results of a series of modeling techniques applied to approximately 28,000 patients from the Expanded Access to Convalescent Plasma program (ClinicalTrials.gov number: NCT04338360) support this hypothesis. This work has implications for the interpretation of clinical studies, the ability to develop effective COVID-19 treatments, and, potentially, for the effectiveness of COVID-19 vaccines as additional locally-evolving variants continue to emerge., (© 2021. The Author(s).)

Background: Convalescent plasma has been widely used to treat coronavirus disease 2019 (Covid-19) under the presumption that such plasma contains potentially therapeutic antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that can be passively transferred to the plasma recipient. Whether convalescent plasma with high antibody levels rather than low antibody levels is associated with a lower risk of death is unknown., Methods: In a retrospective study based on a U.S. national registry, we determined the anti-SARS-CoV-2 IgG antibody levels in convalescent plasma used to treat hospitalized adults with Covid-19. The primary outcome was death within 30 days after plasma transfusion. Patients who were enrolled through July 4, 2020, and for whom data on anti-SARS-CoV-2 antibody levels in plasma transfusions and on 30-day mortality were available were included in the analysis., Results: Of the 3082 patients included in this analysis, death within 30 days after plasma transfusion occurred in 115 of 515 patients (22.3%) in the high-titer group, 549 of 2006 patients (27.4%) in the medium-titer group, and 166 of 561 patients (29.6%) in the low-titer group. The association of anti-SARS-CoV-2 antibody levels with the risk of death from Covid-19 was moderated by mechanical ventilation status. A lower risk of death within 30 days in the high-titer group than in the low-titer group was observed among patients who had not received mechanical ventilation before transfusion (relative risk, 0.66; 95% confidence interval [CI], 0.48 to 0.91), and no effect on the risk of death was observed among patients who had received mechanical ventilation (relative risk, 1.02; 95% CI, 0.78 to 1.32)., Conclusions: Among patients hospitalized with Covid-19 who were not receiving mechanical ventilation, transfusion of plasma with higher anti-SARS-CoV-2 IgG antibody levels was associated with a lower risk of death than transfusion of plasma with lower antibody levels. (Funded by the Department of Health and Human Services and others; ClinicalTrials.gov number, NCT04338360.)., (Copyright © 2021 Massachusetts Medical Society.)

Background: Exercise oscillatory ventilation (EOV) is a consequence of ventilatory control system instability and is commonly observed in patients with advanced heart failure (HF); it is associated with adverse prognosis. The goal of this study was to evaluate the effects of cardiac resynchronization therapy (CRT) on oscillatory ventilation as quantified by a proposed EOV score., Methods and Results: Consecutive patients with HF (N = 35) who underwent clinically indicated CRT, cardiopulmonary exercise testing and carbon dioxide (CO 2 ) chemosensitivity by rebreathe before and 4-6 months after CRT were included in this post hoc analysis. With CRT, EOV scores improved in 22 patients (63%). In these patients, left ventricular ejection fraction, left atrial volume, brain natriuretic peptide concentration, and CO 2 chemosensitivity significantly improved after CRT (P < 0.05). Furthermore, minute ventilation per unit CO 2 production significantly decreased, and end-tidal CO 2 increased at rest and at peak exercise post-CRT. Multiple regression analysis showed only the change of CO 2 chemosensitivity to be significantly associated with the improvement of the EOV score (b = 0.64; F = 11.3; P = 0.004). In the group without EOV score improvement (n = 13), though left ventricular ejection fraction significantly increased with CRT (P = 0.015), no significant changes in ventilation or gas exchange were observed., Conclusion: The EOV score was mitigated by CRT and was associated with decreased CO 2 chemosensitivity., (Copyright © 2020. Published by Elsevier Inc.)

Objective: To provide an update on key safety metrics after transfusion of convalescent plasma in hospitalized coronavirus 2019 (COVID-19) patients, having previously demonstrated safety in 5000 hospitalized patients., Patients and Methods: From April 3 to June 2, 2020, the US Food and Drug Administration Expanded Access Program for COVID-19 convalescent plasma transfused a convenience sample of 20,000 hospitalized patients with COVID-19 convalescent plasma., Results: The incidence of all serious adverse events was low; these included transfusion reactions (n=78; <1%), thromboembolic or thrombotic events (n=113; <1%), and cardiac events (n=677, ~3%). Notably, the vast majority of the thromboembolic or thrombotic events (n=75) and cardiac events (n=597) were judged to be unrelated to the plasma transfusion per se. The 7-day mortality rate was 13.0% (12.5%, 13.4%), and was higher among more critically ill patients relative to less ill counterparts, including patients admitted to the intensive care unit versus those not admitted (15.6 vs 9.3%), mechanically ventilated versus not ventilated (18.3% vs 9.9%), and with septic shock or multiple organ dysfunction/failure versus those without dysfunction/failure (21.7% vs 11.5%)., Conclusion: These updated data provide robust evidence that transfusion of convalescent plasma is safe in hospitalized patients with COVID-19, and support the notion that earlier administration of plasma within the clinical course of COVID-19 is more likely to reduce mortality., (Copyright © 2020. Published by Elsevier Inc.)

BACKGROUNDConvalescent plasma is the only antibody-based therapy currently available for patients with coronavirus disease 2019 (COVID-19). It has robust historical precedence and sound biological plausibility. Although promising, convalescent plasma has not yet been shown to be safe as a treatment for COVID-19.METHODSThus, we analyzed key safety metrics after transfusion of ABO-compatible human COVID-19 convalescent plasma in 5000 hospitalized adults with severe or life-threatening COVID-19, with 66% in the intensive care unit, as part of the US FDA expanded access program for COVID-19 convalescent plasma.RESULTSThe incidence of all serious adverse events (SAEs), including mortality rate (0.3%), in the first 4 hours after transfusion was <1%. Of the 36 reported SAEs, there were 25 reported incidences of related SAEs, including mortality (n = 4), transfusion-associated circulatory overload (n = 7), transfusion-related acute lung injury (n = 11), and severe allergic transfusion reactions (n = 3). However, only 2 of 36 SAEs were judged as definitely related to the convalescent plasma transfusion by the treating physician. The 7-day mortality rate was 14.9%.CONCLUSIONGiven the deadly nature of COVID-19 and the large population of critically ill patients included in these analyses, the mortality rate does not appear excessive. These early indicators suggest that transfusion of convalescent plasma is safe in hospitalized patients with COVID-19.TRIAL REGISTRATIONClinicalTrials.gov NCT04338360.FUNDINGMayo Clinic, Biomedical Advanced Research and Development Authority (75A50120C00096), National Center for Advancing Translational Sciences (UL1TR002377), National Heart, Lung, and Blood Institute (5R35HL139854 and R01 HL059842), National Institute of Diabetes and Digestive and Kidney Diseases (5T32DK07352), Natural Sciences and Engineering Research Council of Canada (PDF-532926-2019), National Institute of Allergy and Infectious Disease (R21 AI145356, R21 AI152318, and AI152078), Schwab Charitable Fund, United Health Group, National Basketball Association, Millennium Pharmaceuticals, and Octapharma USA Inc.

Background: Leadless cardiac pacing (LCP) has emerged as a new modality for permanent pacing. We sought to describe comparative outcomes between LCP and transvenous pacemakers., Methods: Patients receiving LCP (Micra [Medtronic, Minneapolis, MN, USA] and Nanostim [St. Jude Medical/Abbott Laboratories, Chicago, IL, USA]) between 2014 and 2017 at the Mayo Clinic Heart Rhythm Enterprise practice (Rochester, MN, USA; Jacksonville, FL, USA; and Scottsdale, AZ, USA) were identified. We identified 1:1 age- and sex-matched controls receiving single-chamber transvenous ventricular pacemakers (TVP). Statistical analyses were performed with JMP 13.0.0 (SAS, Institute Cary, NC, USA)., Results: Ninety patients underwent LCP implantation (73 Micra and 17 Nanostim) with a median follow-up duration of 62 (interquartile range 28-169) days. Both groups had 100% successful device implant rates. There were no differences in procedure-related major (0% vs 1%) or minor complications (8% vs 3%) in the LCP versus TVP groups (P > 0.05). Excluding Nanostim patients, there was a lower rate of device-related revision or extraction in the Micra versus TVP groups (0% vs 5%, P = 0.028). Device endocarditis was more common in the TVP group (0% vs 3%, P = 0.04). Estimated longevity was greater for the LCP group (median 12.0 vs 10.0 years, P < 0.0001). An increase in severity of tricuspid valve regurgitation (TR) by ≥2 grades occurred in none of the LCP patients, and in 19% of the TVP patients (P = 0.017)., Conclusion: There are no significant differences in procedural complications among patients receiving LCP versus TVP. The Micra group had lower rates of device-related revision/extraction compared to the TVP group. Patients with leadless pacemaker were less likely to develop endocarditis or worsening TR., (© 2019 Wiley Periodicals, Inc.)

Background: Stroke can be a devastating complication in patients with cardiovascular implantable electronic device (CIED) infection. Paradoxical septic embolism can occur in the presence of device leads and patent foramen ovale (PFO) via embolic dislodgment during transvenous lead removal (TLR)., Objective: The purpose of this study was to examine stroke and its associated factors in patients undergoing TLR for CIED infection., Methods: We performed a retrospective analysis of all patients undergoing TLR for CIED infection from January 1, 2000, to July 30, 2017, from all 3 tertiary referral centers at the Mayo Clinic (Rochester, Phoenix, and Jacksonville). The primary outcome was stroke and was further categorized into preprocedural and postprocedural stroke. Associated risk factors were analyzed., Results: A total of 774 patients (mean age 67.6 ± 14.9 years) underwent TLR for CIED infection. The stroke rate in this cohort was 1.9% (95% confidence interval [CI] 1.1%-3.2%). The preprocedural and postprocedural stroke rate was 0.9% (95% CI 0.4%-1.9%) and 1.0% (95% CI 0.4%-2.0%), respectively. PFOs were identified in 46.7% of patients with stroke and in 12.9% of patients without stroke, and were independently associated with stroke (P = .0002). This was especially in patients with right-sided vegetations with right-to-left shunting (odds ratio 6.4; 95% CI 1.3-31.0; P = .022)., Conclusion: In patients with CIED infection undergoing TLR, the presence of PFO, especially with right-sided vegetation with right-to-left shunting, was associated with an increased risk of stroke. This finding suggests that PFO screening before TLR warrants meticulous attention., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The need for pacemaker implantation is a well-described complication of aortic valve replacement. Not so well described is the effect such an event has on long-term outcome. This study reviewed a 21-year experience at the Mayo Clinic (Rochester, Minnesota) with aortic valve replacement to understand the influence of early postoperative pacemaker implantation on long-term mortality rates more clearly., Methods: This study retrospectively reviewed the records of 5,842 patients without previous pacemaker implantation who underwent surgical aortic valve replacement from January 1993 through June 2014. The median age of these patients was 73 years (range, 65 to 79 years), the median ejection fraction was 62% (range, 53% to 68%), 3,853 patients were male (66%), and coronary artery bypass graft operation was performed in 2,553 (44%) of the patients studied. Early pacemaker implantation occurred in 146 patients (2.5%) within 30 days of surgical aortic valve replacement., Results: The median follow-up of patients was 11.1 years (range, 5.8 to 16.5 years), and all-cause mortality rates were 2.4% at 30 days, 6.4% at 1 year, 23.1% at 5 years, 48.3% at 10 years, and 67.9% at 15 years postoperatively. Early pacemaker implantation was associated with an increased risk of death after multivariable adjustment for baseline patients' characteristics (hazard ratio, 1.49; 95% confidence interval, 1.20, 1.84; p < 0.001)., Conclusions: Early pacemaker implantation as a complication of surgical aortic valve replacement is associated with an increased risk of long-term death. Valve replacement-related pacemaker implantation rates should be important considerations with respect to new valve replacement paradigms, especially in younger and lower-risk patients., (Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Background: Heart failure (HF) is characterized by heightened sensitivities of the CO2 chemoreflex and the ergoreflex which promote increased ventilatory drive manifested as increased minute ventilation per volume of expired CO2 (VE/VCO2). The aims of this study were to evaluate the effects of cardiac resynchronization therapy (CRT) on carbon dioxide (CO2) chemosensitivity and the arterial CO2 setpoint., Methods and Results: Consecutive HF patients (n = 35) who underwent clinically indicated CRT were investigated by means of cardiopulmonary exercise testing and CO2 chemosensitivity evaluation with the use of a rebreathe method before and 4-6 months after CRT. Pre- and post-CRT measures were compared with the use of either paired t test or Wilcoxon test. Decreased peak VE/VCO2 (44 ± 10 vs 40 ± 8; P < .01), CO2 chemosensitivity (2.2 ± 1.1 vs 1.7 ± 0.8 L min(-1) mm Hg(-1); P = .04), and increased peak end-tidal CO2 (29 ± 5 vs 31 ± 5 mm Hg; P < .01) were also observed after CRT. Multivariate analysis adjusted for age and sex showed the decrease of peak VE/VCO2 from before to after CRT to be most strongly associated with the increase of peak end-tidal CO2 (β = -0.84; F = 21.5; P < .0001)., Conclusions: Decrease of VE/VCO2 after CRT is associated with decreased CO2 chemosensitivity and increase of the arterial CO2 setpoint, which is consistent with decreased activation of both the CO2 chemoreflex and the ergoreflex., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Pulmonary congestion due to heart failure causes abnormal lung function. Cardiac resynchronization therapy (CRT) is a proven effective treatment for heart failure. The aim of this study was to test the hypothesis that CRT promotes increased lung volumes, bronchial conductance, and gas diffusion. Forty-four consecutive patients with heart failure were prospectively investigated before and after CRT. Spirometry, gas diffusion (diffusing capacity for carbon monoxide), cardiopulmonary exercise testing, New York Heart Association class, brain natriuretic peptide, the left ventricular ejection fraction, left atrial volume, and right ventricular systolic pressure were assessed before and 4 to 6 months after CRT. Pre- and post-CRT measures were compared using either paired Student's t tests or Wilcoxon's matched-pair test; p values <0.05 were considered significant. Improved New York Heart Association class, left ventricular ejection fraction, left atrial volume, right ventricular systolic pressure, and brain natriuretic peptide were observed after CRT (p <0.05 for all). Spirometry after CRT demonstrated increased percentage predicted total lung capacity (90 ± 17% vs 96 ± 15%, p <0.01) and percentage predicted forced vital capacity (80 ± 19% vs 90 ± 19%, p <0.01). Increased percentage predicted total lung capacity was significantly correlated with increased peak exercise end-tidal carbon dioxide (r = 0.43, p = 0.05). Increased percentage predicted forced vital capacity was significantly correlated with decreased right ventricular systolic pressure (r = -0.30, p = 0.05), body mass index (r = -0.35, p = 0.02) and creatinine (r = -0.49, p = 0.02), consistent with an association of improved bronchial conductance and decreased congestion. Diffusing capacity for carbon monoxide did not significantly change. In conclusion, increased lung volumes and bronchial conductance due to decreased pulmonary congestion and increased intrathoracic space contribute to an improved breathing pattern and decreased hyperventilation after CRT. Persistent alveolar-capillary membrane remodeling may account for unchanged diffusing capacity for carbon monoxide., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Background: Patients with preexisting mild cognitive impairment or dementia may be at increased risk for developing cardiac device complications due to an impaired ability to follow postimplant care instructions. We sought to determine whether rates of infection, lead dislodgement, or appropriate or inappropriate implantable cardioverter defibrillator (ICD) shocks are increased in this population., Methods: Medical charts of 561 patients with mild cognitive impairment or dementia who underwent pacemaker (PM) or ICD implantation between January 2002 and October 2009 at Mayo Clinic were identified. A total of 134 patients who were diagnosed with cognitive impairment or dementia before device implantation or within 1 year of implantation were compared with 134 matched controls. Information was collected on patient characteristics, comorbid medical conditions, ejection fraction, complications, device type, device therapy, and mortality. Device information was prospectively entered into a database and retrospectively reviewed., Results: Of the 134 patients with mild cognitive impairment and dementia, 99 underwent PM implantation and 35 underwent ICD implantation. Compared to controls, there was no difference in patient characteristics, ejection fraction, or comorbidities except for diabetes, which was more prevalent in the cognitively impaired and demented group (18.7% vs 30.6%, P = 0.02). There was no difference in device therapy and complications (14.4% vs 5.8%, P = 0.268). However, there was a decreased survival in patients with cognitive impairment and dementia when compared to the control group (42% vs 67% at 5 years, P = 0.007)., Conclusion: Patients with cognitive impairment and standard device indications are not at increased risk for device complications and therapy but their survival is much lower than in matched controls. The cause of this lower survival is unknown but may be related to the underlying neurological disease. Presence of cognitive impairment should therefore be considered when contemplating implantation of a cardiac device., (©2013, The Authors. Journal compilation ©2013 Wiley Periodicals, Inc.)

Background: Sudden death may occur after radiofrequency catheter ablation of the atrioventricular node (AVN) and permanent pacemaker implantation. It is unclear whether a faster initial heart rate with gradual rate reduction decreases the risk of sudden death., Objective: To evaluate the effects of initial pacing at a faster rate after AVN ablation, with a gradual rate decrease over 3 months, on the rate of sudden death in patients with atrial fibrillation., Methods: We compared the rate of likely or possible procedure-related sudden death in 2 groups of patients who had AVN ablation and pacemaker implantation. The study cohort was treated between January 2005 and December 2009, and pacemakers were programmed to a lower rate of 90 beats/min after the procedure, with a monthly decrement of 10 beats/min until 60 beats/min was reached. The control group was treated between July 1990 and December 1998 when pacemakers were programmed to a lower rate of 60 beats/min immediately after ablation., Results: The study cohort included 520 patients (mean age 73.6 ± 10.3 years), and the control cohort comprised 334 patients (mean age 68.1 ± 1.1 years). Sudden death deemed likely or possibly related to ablation and pacemaker implantation occurred in 1 patient in the study cohort (0.2%) and in 7 patients (2.1%) in the control group (P = .007)., Conclusions: Sudden death was significantly decreased in the study cohort compared to controls. The faster lower pacing rate immediately after AVN ablation with a gradual decrease is a plausible mechanism for the improved clinical outcome., (Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

With increasing coronary sinus (CS) pacemaker leads for cardiac resynchronization therapy, the need to remove these leads has risen. The purpose of this study is to describe a single center's experience with CS lead removal and to attempt to identify predictors of difficulty with lead removal and complications. We reviewed all percutaneous endocardial CS lead removals performed at our institution through February 2010. Successful removal with traction alone was considered simple while complex extractions required traction devices and/or laser sheaths. Between December 1996 and February 2010, 125 CS leads were percutaneously removed ≥1 week post-implantation from 115 patients. One attempt at CS lead extraction was unsuccessful. The average duration since implantation for the CS leads was 1.54 years (± .75 years, range 8 days to 8.24 years). The majority of the leads were removed by simple traction (n = 114, 91.2 %). The remainder were removed by femoral approach with snare (n = 3, 2.4 %), locking stylet (n = 2, 1.6 %), or locking stylet and laser sheath (n = 6, 4.8 %). Half of CS leads in place greater than 4 years required complex extraction (n = 7/14, 50 %). CS complications (n = 11 patients, 8.8 %) included CS or tributary thrombosis (n = 7/102, 6.9 %) and CS dissection (n = 4/102, 3.9 %). Major non-CS complications (n = 2 patients, 1.6 %) included a cardiac tear requiring pericardiocentesis and thoracotomy (n = 1, 0.8 %) and subclavian vein tear requiring surgical repair (n = 1, 0.8 %). Minor non-CS complications (n = 9 patients, 7.2 %) included a pneumothorax (n = 1, 0.8 %), hematoma (n = 2, 1.6 %), subclavian vein thrombosis (n = 3, x%), and blood transfusion (n = 5, 4.0 %). A longer duration since implantation and larger lead diameter were associated with complex versus simple removal (p < .0001 and p = .0009 respectively). Percutaneous CS lead removal is successful by simple traction alone in the vast majority of cases. CS leads in place greater than 4 years, however, often require complex extraction. Specific extraction techniques can be implemented when simple traction is unsuccessful without an appreciable increase in complications.

Introduction: Pacemaker therapy is effective in reducing recurrent syncope in patients with symptomatic carotid sinus hypersensitivity (CSH), yet the optimal pacing modality for this syndrome is not known. The objective of this study is to prospectively investigate the impact of three pacing methods (DDDR vs DDDR with sudden bradycardia response [SBR] vs VVI) on recurrent syncope and quality of life., Methods: Twenty-one patients with symptomatic CSH (syncope or near syncope) were randomized to VVI, DDDR, or DDDR with SBR on a double-blinded basis in a sequential crossover fashion with 6 months in each mode. The primary endpoints were recurrent events and quality of life (assessed by SF-36). The mean number of events and SF-36 scores were compared., Results: At baseline, over the preceding 6 months, there were a total of 29 syncopal events and 258 presyncopal events among 21 patients. Following pacing in any mode, the total number of these syncopal events reduced to two in two patients (P < 0.001) and 17 presyncopal events (P < 0.001) in 12 patients. The mean number of events was not significantly different between the three pacing methods. SF-36 scores revealed some minor benefits of DDDR pacing versus baseline in the categories, but no pacing method was found to be superior., Conclusions: The study was unable to confirm the initial study hypothesis of a superiority of one pacing modality over another. Quality of life measures allude to potential benefit from DDDR pacing alone., (©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.)

Aims: The risk of contrast-induced nephropathy (CIN) with radiocontrast use during left ventricular (LV) lead placement for cardiac resynchronization therapy (CRT) is unknown. It is unclear as to whether minimizing contrast use impacts adequacy of LV lead placement., Methods and Results: A retrospective analysis was performed of all LV leads placed for CRT at Mayo Clinic, Rochester, MN from 16 March 2001 to 1 April 2009. The primary goal was to assess risk of CIN and adequacy of lead placement depending on the amount of contrast administered during CRT placement. Contrast-induced nephropathy was defined as a ≥25% increase in serum creatinine ≥48 h post-procedurally. Adequacy of lead placement was assessed in a blinded fashion by review of procedural fluoroscopic and post-procedural radiographic images. Eight hundred and twenty-two subjects were divided based on the amount of procedural contrast used into tertile 1 (<55 mL, 257 patients), tertile 2 (55-94 mL, 261 patients), and tertile 3 (≥95 mL, 304 patients). Contrast-induced nephropathy occurred in 5.4% of patients in tertile 1, 5.4% in tertile 2 and 11.8% in tertile 3 (P = 0.004). Among the tertiles, lead positioning was optimal in 95, 80 and 66%, respectively (P < 0.0001). Fluoroscopic time was 34 ± 23, 42 ± 26, and 48 ± 30 min in tertiles 1, 2, and 3 (P < 0.0001)., Conclusion: Risk of CIN with CRT implantations was substantial. Increased volume of radiocontrast used for LV lead placement was associated with substantially increased risk of CIN. Minimal contrast use was associated with decreased procedural times without adverse impact on adequacy of lead placement.

Objective: This study aimed to characterize the interactions of pacemakers with magnetic resonance imaging (MRI) and to identify device characteristics that could predict adverse interactions., Background: The safety of MRI in patients with indwelling pacemaker systems remains uncertain. Previous studies demonstrated safety in most patients, but unpredictable, potentially concerning changes in pacemaker behavior have occurred., Methods: We prospectively studied patients with pacemaker devices in situ who were not pacemaker dependent and in whom MRI was essential for adequate diagnosis and treatment. All patients were monitored by electrocardiography and pulse oximetry during scanning; devices were interrogated and cardiac enzymes were measured before and after scanning., Results: Of 32 patients studied (46 MRI examinations), 28 patients had a dual-chamber system and one had a biventricular device. Regions scanned were the head and spine. Devices were reprogrammed to asynchronous pacing or sense-only mode in all except six patients before MRI. During six scanning episodes (five patients), "power-on" resetting of the device was noted. Magnet-mode pacing was noted during four episodes (three patients). Occasional premature ventricular contractions were noted in one patient. No significant changes in battery voltage, sensed P wave and R wave, pacing thresholds, lead impedance, or cardiac enzymes were noted immediately after MRI or at 1-month follow-up., Conclusions: Overall, no significant changes were seen in pacemaker device function, and no adverse clinical events were observed. A minority of patients with older devices had unpredictable changes in device behavior, which stresses the need for close monitoring during and careful device interrogation after scanning.

Purpose: The purpose of this study is to describe the results of manual and automatic electronic medical record-based screening of patients at risk of sudden cardiac arrest (SCA) based on measurements of left ventricular ejection fraction (LVEF)., Methods: Counseling regarding SCA risk and implantable cardioverter defibrillator (ICD) therapy is underutilized in patients with reduced LVEF. We developed and implemented an electronic medical record (EMR)-based system for screening of such patients to improve care. In phase one, manual screening of electronic records and LVEF databases was initially performed by trained cardiac device nurses. In phase two, records were screened automatically by a customized program, and candidate patient records were sent to cardiac device nurses for final review and disposition., Results: In phase one, 2,531 patients with LVEF ≤35% were identified over 398 days. Manual EMR review showed that 1,918 patients (76%) received appropriate counseling regarding SCA risk, received ICDs, or had disqualifying comorbidities. In phase two, 1,081 patients with LVEF ≤35% were identified after automatic screening of 44,672 echocardiograms and EMR over 251 days. Of these, 513 patients (58%) received appropriate counseling regarding SCA risk, received ICDs, or had disqualifying comorbidities., Conclusions: These data detail the utilization of consultation regarding SCA risk and ICDs in patients with reduced LVEF at a tertiary care center with ready access to arrhythmia specialists. Notification of primary providers of reduced LVEF with recommendation for consultation was not effective in improving patient care.

Objectives: This study sought to compare all-cause mortality in patients with Fidelis leads (Medtronic, Minneapolis, Minnesota) to those with a nonadvisory lead., Background: Although Fidelis leads are prone to fracture, and rare deaths due to lead failure have been reported, it is unclear whether the presence of a Fidelis lead is associated with increased mortality. This study compares all-cause mortality in a large cohort of patients with Fidelis and Quattro implantable cardioverter-defibrillator (ICD) leads., Methods: All patients with Fidelis (Medtronic models 6931, 6948, and 6949) and Quattro (Medtronic model 6947) leads followed at 3 tertiary care centers were identified from the medical records (implant dates: November 19, 2001, to December 23, 2008). Clinical and device-specific data were collected into a common database. Deaths were identified from medical records and the Social Security Death Index. Survival was estimated using the Kaplan-Meier method., Results: A total of 2,671 patients (1,030 Fidelis and 1,641 Quattro) were identified. There were 398 deaths: 147 in the Fidelis group (mean follow-up: 34.4 months) and 251 in the Quattro group (mean follow-up: 39.9 months). No deaths were associated with 85 Fidelis and 23 Quattro failures. At 4 years, survival was diminished in patients with Fidelis compared with Quattro leads (80.7% vs. 83.9%, p = 0.025). After adjustment for factors associated with mortality, survival was similar between groups. One hundred percent pacing was not associated with mortality. Elective removal of nonfailed leads was performed in 5.1% of Fidelis and 0.9% of Quattro patients., Conclusions: In a conservatively managed cohort, in whom observation was predominantly utilized, adjusted survival is similar between patients with Fidelis and Quattro ICD leads., (Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Switching warfarin for heparin has been a practice for managing periprocedural anticoagulation in high-risk patients undergoing device-related procedures. We sought to investigate whether continuation of warfarin sodium therapy without heparin bridging is safe and, when it is continued, the optimal international normalized ratio (INR) without increased bleeding risk at time of device-related procedure., Methods and Results: We retrospectively studied 766 consecutive patients taking warfarin long term who underwent device-related procedures. Patients were grouped by treatment: discontinued warfarin (-warfarin, n = 243), no interruption of warfarin (+warfarin, n = 324), and discontinued warfarin with heparin bridging (+heparin, n = 199). The study primary endpoint was systemic bleeding or formation of moderate or severe pocket hematoma within 30 days of the procedure. Thirty-one (4%) patients had bleeding events, including pocket hematoma in 29 patients. The bleeding events occurred more often for +heparin (7.0%) than -warfarin (2.1%) or +warfarin (3.7%, P = 0.029). For +warfarin group, INR of 2.0-2.5 at time of procedure did not increase bleeding risk compared with INR less than 1.5 (3.7% vs 3.4%; P = 0.72), but INR greater than 2.5 increased the bleeding risk (10.0% vs 3.4%; P = 0.029). Concomitant aspirin use with warfarin significantly increased bleeding risk than warfarin alone (5.6% vs 1.4%, P = 0.02). Median length of hospitalization was significantly shorter for +warfarin than +heparin (1 vs 6 days; P < 0.001)., Conclusion: Continuation of oral anticoagulation therapy with an INR level of <2.5 does not impose increased risk of bleeding for device-related procedures, although precaution is necessary to avoid supratherapeutic anticoagulation levels., (©2011, The Authors. Journal compilation ©2011 Wiley Periodicals, Inc.)

Objective: The purpose of this study was to determine if anodal stimulation accounts for failure to benefit from cardiac resynchronization therapy (CRT) in some patients., Background: Approximately 30-40% of patients with moderate to severe heart failure do not have symptomatic nor echocardiographic improvement in cardiac function following CRT. Modern CRT devices allow the option of programming left ventricular (LV) lead pacing as LV tip to right ventricular (RV) lead coil to potentially improve pacing thresholds. However, anodal stimulation can result in unintentional RV pacing (anode) instead of LV pacing (cathode)., Methods: Patients enrolled in our center's CRT registry had an echocardiogram, 6-minute walk (6MW), and Minnesota Living with HF Questionnaire (MLHFQ) pre-implant and 6 months after CRT. Electrocardiograms (12 lead) during RV, LV, and biventricular (BiV) pacing were obtained at the end of the implant in 102 patients. Anodal stimulation was defined as LV pacing QRS morphology on EKG being identical to RV pacing or consistent with fusion with RV and LV electrode capture. LV end systolic volume (LVESV) was measured by echo biplane Simpson's method and CRT responder was defined as 15% or greater reduction in LVESV., Results: Of the 102 patients, 46 (45.1%) had the final LV lead pacing configuration programmed LV (tip or ring) to RV (coil or ring). 3 of the 46 subjects (6.5%) had EKG findings consistent with anodal stimulation, not corrected intraoperatively. All anodal stimulation patients were nonresponders to CRT by echo criteria (reduction in LVESV 13.3 ± 0.6%, increase in EF 5.0 ± 1.4%) compared to 46% responders for those without anodal stimulation, (change in LVESV 18.7 ± 25.6%, EF 7.6 ±10.9%). None of the anodal stimulation patients were responders for the 6 minute walk, compared to 32 of 66 (48%) of those without anodal stimulation., Conclusion: Anodal stimulation is a potential underrecognized and ameliorable cause of poor response to CRT.

Background: The objective of the present study was to investigate the effect of cardiac resynchronization therapy (CRT) on cardiac autonomic function., Methods and Results: This prospective study included 45 consecutive patients with heart failure who received CRT devices with defibrillator and 20 age-matched, healthy control subjects. At baseline and 3 months and 6 months after CRT, we assessed New York Heart Association (NYHA) class, 6-minute walk distance, plasma sympathetic biomarker nerve growth factor, echocardiography, heart rate variability and cardiac presynaptic sympathetic function determined by iodine 123 metaiodobenzylguanidine scintigraphy. After CRT, NYHA class improved by 1 class (P<0.001), and left ventricular ejection fraction increased by 8% (P<0.001). Along with improvement in the standard deviation of all normal-to-normal R-R intervals (85.63±31.66 ms versus 114.79±38.99 ms; P=0.004) and the standard deviation of the averaged normal-to-normal R-R intervals (82.62±23.03 ms versus 100.50±34.87 ms; P=0.004), the delayed heart/mediastinum (H/M) ratio increased (1.82 [0.58] versus 1.97 [0.59]; P=0.03), whereas the mean (SD) H/M washout rate was reduced (48% [19%] versus 37% [22%]; P=0.01). Twenty-two of 45 study patients responded to CRT, with a reduction of left ventricular end-systolic volume index >15%. Compared with nonresponders, responders had a higher delayed H/M ratio (2.11 versus 1.48; P=0.003) and lower H/M washout rate (37% versus 62%; P=0.003) at baseline., Conclusions: CRT improved sympathetic function. Cardiac sympathetic reserve may be a marker for the reversibility of failing myocardial function.

Background: Cardiac resynchronization therapy (CRT) is a therapy of proven benefit in patients with advanced heart failure. Identifying potential responders remains challenging, and whether the etiology of the heart failure is related to the potential hemodynamic benefit and long-term outcome of CRT is unclear., Objective: The purpose of this study was to evaluate whether heart failure etiology (ischemic cardiomyopathy [ICM] vs nonischemic dilated cardiomyopathy [DCM]) was associated with CRT outcome and implantable cardioverter-defibrillator (ICD) shocks., Methods: The study included 503 CRT recipients (CRT-D 90%) in a longitudinal CRT database: ICM (n = 312) and DCM (n = 191). Clinical variables and echocardiographic measures preimplant and postimplant were collected. Actuarial survival and ICD therapy data were assessed with Kaplan-Meier curve and log rank tests., Results: Pre-CRT, ICM patients were older and had higher creatinine levels (P <.001). At median follow-up of 7.1 months, the DCM group experienced greater improvement in left ventricular ejection fraction (8.3% ± 10% vs 6.2% ± 10%, P = .05) and left ventricular end-diastolic volumes than did those with ICM (-28%.4 ± 53 mL vs -15.3 ± 46 mL, P = .024). Survival estimates at 4 years were 55% for ICM and 77% for DCM groups (P <.001), respectively, whereas no significant difference in the incidence of appropriate/inappropriate ICD shocks was observed. The ICM group remained at higher risk for death compared to the DCM group after controlling for preimplant variables (hazard ratio 1.6, 95% confidence interval 1.1-2.3, P = .008)., Conclusion: In response to CRT and in contrast to ICM, DCM patients experienced greater improvement in left ventricular systolic function and reverse remodeling while also sustaining a greater survival benefit., (Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Cardiac resynchronization therapy (CRT) benefits patients with advanced heart failure. The role of atrioventricular nodal (AVN) ablation in improving CRT outcomes, including survival benefit in CRT recipients with atrial fibrillation, is uncertain., Objective: The purpose of this study was to assess the impact of AVN ablation on clinical and survival outcomes in a large atrial fibrillation and heart failure population that met the current indication for CRT and to determine whether AVN ablation is an independent predictor of survival in CRT recipients., Methods: Of 154 patients with atrial fibrillation who received CRT-D, 45 (29%) underwent AVN ablation (+AVN-ABL group), whereas 109 (71%) received drug therapy for rate control during CRT (-AVN-ABL group). New York Heart Association (NYHA) class, electrocardiogram, and echocardiogram were assessed before and after CRT. Survival data were obtained from the national death and location database (Accurint)., Results: CRT comparably improved left ventricular ejection fraction (8.1% +/- 10.7% vs 6.8% +/- 9.6%, P = .49) and left ventricular end-diastolic diameter (-2.1 +/- 5.9 mm vs -2.1 +/- 6.7 mm, P = .74) in both +AVN-ABL and -AVN-ABL groups. Improvement in NYHA class was significantly greater in the +AVN-ABL group than in -AVN-ABL group (-0.7 +/- 0.8 vs -0.4 +/- 0.8, P = .04). Survival estimates at 2 years were 96.0% (95% confidence interval [CI] 88.6%-100%) for +AVN-ABL group and 76.5% (95% CI 68.1%-85.8%) for-AVN-ABL group (P = .008). AVN ablation was independently associated with survival benefit from death (hazard ratio [HR] 0.13, 95% CI 0.03-0.58, P = .007) and from combined death, heart transplant, and left ventricular assist device (HR 0.19, 95% CI 0.06-0.62, P = .006) after CRT., Conclusion: Among patients with atrial fibrillation and heart failure receiving CRT, AVN ablation for definitive biventricular pacing provides greater improvement in NYHA class and survival benefit. Larger-scale randomized trials are needed to assess the clinical and survival outcomes of this therapy., (Copyright 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Whether mechanical dyssynchrony indices predict reverse remodeling (RR) or clinical response to cardiac resynchronization therapy (CRT) remains controversial. This prospective study evaluated whether echocardiographic dyssynchrony indices predict RR or clinical response after CRT., Methods and Results: Of 184 patients with heart failure with anticipated CRT who were prospectively enrolled, 131 with wide QRS and left ventricular ejection fraction <35% had 6-month follow-up after CRT implantation. Fourteen dyssynchrony indices (feasibility) by M-mode (94%), tissue velocity (96%), tissue Doppler strain (92%), 2D speckle strain (65% to 86%), 3D echocardiography (79%), and timing intervals (98%) were evaluated. RR (end-systolic volume reduction ≥15%) occurred in 55% and more frequently in patients without (71%) than in patients with (42%) ischemic cardiomyopathy (P=0.002). Overall, only M-mode, tissue Doppler strain, and total isovolumic time had a receiver operating characteristic area under the curve (AUC) greater than the line of no information, but none of these were strongly predictive of RR (AUC, 0.63 to 0.71). In nonischemic cardiomyopathy, no dyssynchrony index predicted RR. In ischemic cardiomyopathy, M-mode (AUC, 0.67), tissue Doppler strain (AUC, 0.79), and isovolumic time (AUC, 0.76) -derived indices predicted RR (P<0.05 for all), although the incremental value was modest. No indices predicted clinical response assessed by Minnesota Living with Heart Failure Questionnaire, 6-minute walk distance, and peak oxygen consumption., Conclusions: These findings are consistent with the Predictors of Response to CRT study and do not support use of these dyssynchrony indices to guide use of CRT.

Introduction: The Medtronic Sprint Fidelis implantable cardioverter defibrillator (ICD) lead was "recalled" in October 2007 after 268,000 implants worldwide due to increased failure risk. Manufacturer suggested monitoring has not been shown effective at preventing adverse events. Only limited data exist regarding clinical predictors of Fidelis lead fracture. We sought to identify risk factors for Fidelis fracture to guide clinical monitoring and compare its performance with a control lead., Methods: Fractured lead cases were retrospectively reviewed for demographic data, implant technique, radiographic appearance and clinical presentation was analyzed. Lead survival was compared using Kaplan-Meir curves., Results: Study patients (n = 1314) experienced 18 Fidelis and 6 Quattro lead fractures. Patients with failed Fidelis leads were younger than those with surviving leads (49.5 vs 64.6 years, P = 0.0066). Fidelis lead fractures often occurred around the time of physical activity. No other measured demographic or technique related factors were associated with lead fracture. Fidelis leads had significantly decreased survival compared with Quattro leads (89.3 vs 98.9% at 30 months). Patients less than 50 years old had significantly decreased lead survival compared with those older than 50 in both Fidelis (79.6% vs 96.5% at 24 months) and Quattro (93.4 vs 99.8%, P < 0.001 at 24 months) leads., Conclusions: Patients under age 50, with either Fidelis or Quattro ICD leads, are at increased risk of lead fracture compared with patients over 50, particularly around the time of intense physical activity. Aggressive monitoring and advisory programming appears warranted in patients with Fidelis leads as well as especially in younger patients.

Background: Right ventricular pacing increases the risk of heart failure in adults with structural heart disease. The impact of prolonged right ventricular pacing in adults without structural heart disease is not fully characterized and may depend on interactions of pacing with abnormal substrate predisposing to ventricular dysfunction., Methods and Results: We assessed the effect of right ventricular pacing in patients who underwent pacemaker implantation for isolated congenital atrioventricular block between 1964 and 2005. To assess for immunologic contribution to cardiac dysfunction, outcomes were compared between patients with (Ab(+)) and without (Ab(-)) antinuclear antibody during adulthood and an age- and sex-matched Olmsted County, Minnesota, population. Of 103 patients (mean+/-SD age, 32+/-19 years), 18 were Ab(+). Long-term survival free of new heart failure after pacemaker implantation in isolated congenital atrioventricular block patients was worse than in the matched population (P<0.001). This difference was attributable to the development of heart failure in 12 Ab(+) patients (67%; P<0.001), without differences between Ab(-) patients (2%) and the matched population (2%; P=0.7). Compared with baseline, at last follow-up, left ventricular ejection fraction did not decline in Ab(-) (53+/-9% to 57+/-12%) but decreased in Ab(+)(52+/-10% to 38+/-12%; P=0.03) patients. Survival was similar in Ab(-) patients and the Minnesota population (98%; P=0.7) but worse in Ab(+) patients (79%; P<0.01)., Conclusions: The natural history of patients with isolated congenital atrioventricular block who require pacing depends upon their antibody status. Antinuclear antibody status was a predictor for the development of heart failure and death. Long-term right ventricular pacing alone does not appear to be associated with development of heart failure, deterioration in ventricular function, or reduced survival in Ab(-) isolated congenital atrioventricular block patients.

Background: Cardiac resynchronization therapy (CRT) improves outcomes in patients with left bundle branch block (LBBB), but the benefits of CRT in patients with other QRS morphologies or previous pacing are uncertain., Objective: The purpose of this study was to describe outcomes in patients with prior right ventricular pacing and non-LBBB morphologies., Methods: We studied 505 patients who underwent de novo CRT (n = 338) or CRT upgrade (n = 167). De novo patients were categorized by underlying QRS morphology: LBBB (67%), right bundle branch block (RBBB; 11%), intraventricular conduction delay (IVCD; 13%), and QRS <120 ms (9%). Upgrade patients were categorized by the percentage of previous ventricular pacing., Results: Patients were followed for death over a median of 2.6 years (interquartile range 1.6-4.0). New York Heart Association (NYHA) functional class and echocardiographic improvements were similar in de novo and upgrade patients. However, within the de novo group, NYHA improvements were less in patients with RBBB (0.3 +/- 0.8; P = .014) or IVCD (0.2 +/- 0.7; P = .001) than in those with LBBB (0.7 +/- 0.8). These patients had less left ventricular functional improvement as well. Survival was comparable after de novo versus upgrade CRT (61% vs 63% at 4 years; P = .906). No clinical or survival differences were noted in upgrade patients based on the percentage of previous pacing. However, survival in de novo CRT recipients with RBBB (32%) was lower than in those with LBBB (66%; P <.001), and RBBB independently predicted death (hazard ratio 3.5, confidence interval 1.9-6.5; P <.001)., Conclusion: RBBB and IVCD result in less clinical improvement or worsened survival after CRT. Additional selection criteria may be beneficial in identifying potential responders with RBBB, IVCD, or narrow QRS.

Background: Left ventricular endocardial pacing leads placed via the coronary sinus (CS) are increasingly implanted to achieve cardiac resynchronization therapy (CRT); however, the long-term stability of these leads is unknown. We sought to determine the implant success and long-term stability of CS leads in our single center experience., Methods: All consecutive patients who underwent CRT via implantation of the CS lead between January 1999 and December 2005 were included. Pacing thresholds at implant and during long-term follow-up were reviewed and the rate of acute (within 24 hours of implant) and chronic (>24 hours) lead failure was determined., Results: A total of 512 patients (mean age 68 +/- 12 years; 409 [80%] male) underwent CRT device implantation and were included. The CS lead implantation was successful on the initial implantation in 487 patients (95%) and subsequently successful in six patients (24%) in whom initial attempts were unsuccessful. Acute lead failure occurred in 25 patients (5.1%) and was most commonly due to persistent extra-cardiac stimulation. The rate of chronic lead failure was 4% in the first year and remained stable during long-term follow-up. The CS lead pacing thresholds remained stable with only minimal increase (1.42 +/- 0.85 V/0.42 +/- 0.25 ms vs 1.51 +/- 1.05 V/0.47 +/- 0.29 ms; P = 0.04)., Conclusions: Placement of a left ventricular pacing lead via the CS is feasible and safe in the vast majority of patients. Once placed, the CS leads remain stable with excellent pacing thresholds over the longer term.

The Medtronic Riata implantable cardioverter-defibrillator (ICD) lead is a 7-Fr ICD lead shown to have a propensity for cardiac perforation. This report details two pediatric cases of cardiac perforation in patients with a Riata ICD lead. Analysis regarding the effect of ICD implantation techniques on cardiac perforation specific to pediatric patients is discussed.

Background: With the increased number of implantable cardioverter-defibrillator (ICD) recipients and the frequent need for device upgrading, lead malfunction is a concern, but the optimal approach to managing nonfunctioning leads is unknown., Objective: The purpose of this study was to determine the rate and characteristics of complications related to abandoned ICD leads., Methods: Patients with abandoned leads were identified by retrospective review of the Mayo Clinic ICD database from August 1993 to May 2002. We reviewed the medical records to assess long-term follow-up for venous thromboembolic complications, device sensing malfunction, appropriateness of delivered shocks, defibrillation threshold (DFT) values before and after lead abandonment, and subsequent surgical procedures related to devices or leads., Results: We identified 78 ICD patients (81% males; mean age 63 +/- 14 years) with 101 abandoned leads (69 in the right ventricle, 31 in the right atrium or superior vena cava, 1 in the coronary sinus). During a mean follow-up of 3.1 +/- 2.0 years, neither sensing malfunction nor venous thromboembolic complications were detected. DFT values were high in 13 patients (17%), but there was no significant increase in mean DFT values before and after lead abandonment in 43 patients for whom both values were available (16.2 +/- 9.2 J before abandonment vs 14.1 +/- 5.5 J after; P = .24). Fourteen patients (18%) required further ICD-related surgery; none of these operations were attributed to abandoned leads. Five-year rates of appropriate and inappropriate shocks were 25.9% and 20.5%, respectively., Conclusion: Abandoning a nonfunctioning lead appears to be safe and does not pose a clinically significant additional risk of future complications.

Objective: To determine the effect of cardiac resynchronization therapy (CRT) on sympathetic nervous function in heart failure (HF)., Background: Neurohormonal dysregulation and cardiac autonomic dysfunction are associated with HF and contribute to HF progression and its poor prognosis. We hypothesized that mechanical resynchronization improves cardiac sympathetic function in HF., Methods: Sixteen consecutive patients receiving CRT for advanced cardiomyopathy and 10 controls were included in this prospective study. NYHA class, 6-minute walk distance, echocardiographic parameters, plasma norepinephrine (NE) were assessed at baseline, 3-month and 6-month follow-up. Cardiac sympathetic function was determined by (123)iodine metaiodobenzylguanidine ((123)I-MIBG) scintigraphy and 24-hour ambulatory electrocardiography., Results: Along with improvement in NYHA class (3.1 +/- 0.3 to 2.1 +/- 0.4, P < 0.001) and LVEF (23 +/- 6% to 33 +/- 12%, P < 0.001), delayed heart/mediastinum (H/M) (123)I-MIBG ratio increased significantly (1.8 +/- 0.7 to 2.1 +/- 0.6, P = 0.04) while the H/M (123)I-MIBG washout rate decreased significantly (54 +/- 25% to 34 +/- 24%, P = 0.01) from baseline to 6-month follow-up. The heart rate variability (HRV) measured in SD of normal-to-normal intervals also increased significantly from baseline (82 +/- 30 ms) to follow-up (111 +/- 32 ms, P = 0.04). The improvement in NYHA after CRT was significantly associated with baseline (123)I-MIBG H/M washout rate (r = 0.65, P = 0.03). The improvement in LVESV index was associated with baseline (123)I-MIBG delayed H/M ratio (r =-0.67, P = 0.02) and H/M washout rate (r = 0.65, P = 0.03)., Conclusion: After CRT, improvements in cardiac symptoms and LV function were accompanied by rebalanced cardiac autonomic control as measured by (123)I-MIBG and HRV.

Background: Hypertrophic cardiomyopathy (HCM) is often accompanied by atrial fibrillation (AF) due to diastolic dysfunction, elevated left atrial pressure, and enlargement. Although catheter ablation for drug-refractory AF is an effective treatment, the efficacy in HCM remains to be established., Methods: Thirty-three consecutive patients (25 male, age 51 +/- 11 years) with HCM underwent pulmonary vein (PV) isolation (n = 8) or wide area circumferential ablation with additional linear ablation (n = 25) for drug-refractory AF. Twelve-lead and 24-hour ambulating ECGs, echocardiograms, event monitor strips, and SF 36 quality of life (QOL) surveys were obtained before ablation and for routine follow-up., Results: Twenty-one (64%) patients had paroxysmal AF and 12 (36%) had persistent/permanent AF for 6.2 +/- 5.2 years. The average ejection fraction was 0.63 +/- 0.12. The average left atrial volume index was 70 +/- 24 mL/m(2). Over a follow-up of 1.5 +/- 1.2 years, 1-year survival with AF elimination was 62%(Confidence Interval [CI]: 66-84) and with AF control was 75%(CI: 66-84). AF control was less likely in patients with a persistent/chronic AF, larger left atrial volumes, and more advanced diastolic disease. Additional linear ablation may improve outcomes in patient with severe left atrial enlargement and more advanced diastolic dysfunction. Two patients had a periprocedureal TIA, one PV stenosis, and one died after mitral valve replacement from prosthetic valve thrombosis. QOL scores improved from baseline at 3 and 12 months., Conclusion: Outcomes after AF ablation in patients with HCM are favorable. Diastolic dysfunction, left atrial enlargement, and AF subtype influence outcomes. Future studies of rhythm management approaches in HCM patients are required to clarify the optimal clinical approach.

Background: Various dyssynchrony indexes derived from tissue velocity and strain imaging have been proposed to predict the effectiveness of cardiac resynchronization therapy (CRT). We sought to compare the effect of CRT on dyssynchrony indexes derived by tissue velocity and strain and to determine which baseline intraventricular dyssynchrony parameters correlate with improvement in left ventricular volume after CRT., Methods and Results: Echocardiography with tissue Doppler imaging was performed in 45 patients with systolic heart failure at baseline, 1 day after CRT, and a median of 6 months after CRT. We calculated septal-lateral delay and anteroseptal-posterior delay and standard deviation of time to peak systolic velocity in the 12 basal and mid-left ventricular segments (Tv-SD). The standard deviation for time to peak strain in the 12 basal and mid-left ventricular segments (Tepsilon-SD) was calculated as a strain-derived dyssynchrony index. None of the tissue velocity-derived dyssynchrony indexes improved after CRT (septal-lateral delay, P=0.39; anteroseptal-posterior delay, P=0.46; Tv-SD, P=0.30), whereas Tepsilon-SD decreased significantly after CRT (P<0.001). Improvement in Tepsilon-SD 1 day after CRT correlated with the reduction in end-systolic volume at follow-up (r=0.66; P<0.001). Baseline Tepsilon-SD demonstrated significant correlation with the reduction of end-systolic volume at follow-up (r=0.57; P<0.001); however, baseline tissue velocity-derived dyssynchrony indexes failed to predict the effect of CRT., Conclusions: The strain-derived dyssynchrony index is a better measurement than the tissue velocity dyssynchrony index for monitoring changes in mechanical dyssynchrony after CRT and for predicting reduction in left ventricular volume after CRT.

Background: Outflow tract ventricular tachycardia originating above the semilunar valves has been reported in a small number of studies. Discrete potentials in the great arteries (above the semilunar valves) have been rarely described in patients undergoing electrophysiology evaluation and radiofrequency ablation for ventricular arrhythmias. The mechanisms of these discrete potentials in the great arteries and the utility of such potentials in guiding radiofrequency ablation are unknown., Methods and Results: Twelve patients with outflow tract ventricular arrhythmia originating above the semilunar valves with discrete arterial potentials were studied. The clinical characteristics, properties of the arterial potentials, electrophysiological evaluation and ablation, and short- and long-term outcomes were reviewed. Of the twelve patients, 8 (67%) were women. The patients' average age was 41+/-14 years. The average ejection fraction was 0.52+/-0.16 (range: 0.16 to 0.75). Contact mapping in the great artery demonstrated discrete near-field electrograms that were separate from far-field ventricular electrograms in all patients (8 above the pulmonary valve and in 4 the aortic valve). One or more of the following electrophysiological characteristics, supportive of an arrhythmogenic substrate, were observed in 10 of 12 patients: (1) A fixed or reproducibly variable pattern of discrete potential-ventricular arrhythmia relationship was present at baseline or during pacing; (2) the discrete potential-ventricular electrogram relationship during sinus rhythm was the reverse of that during the ventricular arrhythmia; (3) during sustained ventricular tachycardia, spontaneous variation of the ventricular (V-V) cycle length was preceded by a similar variation of arterial spike potential-spike potential cycle length; and (4) ablation guided by the discrete arterial potential successfully eliminated the clinical arrhythmia. Ablation was successful in these patients. In the remaining 2 patients, the potentials were believed to be bystanders. Over 10+/-4 months (range: 5 to 32 months) of follow-up, there have been no recurrences of the premature ventricular complex or ventricular arrhythmia., Conclusions: Discrete potentials are present in the great arteries of a select group of patients with outflow tract ventricular tachycardia originating above the semilunar valves. When an arrhythmogenic relationship can be demonstrated, discrete potentials are useful in guiding ablation within the great vessels, despite significant anatomic complexity.

Objective: To determine whether survival after cardiac resynchronization therapy (CRT) is related to improvement in clinical or echocardiographic parameters., Background: In clinical trials, CRT improved symptoms, left ventricular (LV) structure, function, and survival. In clinical practice, response to CRT is highly variable and whether survival benefit is confined to those patients who experience improvement in clinical status or cardiac structure and function is unclear., Methods: This is a single-center study of patients receiving clinically indicated CRT between January 2002 and December 2004., Results: Of 309 patients (age 68 +/- 11 years, 83% male) receiving CRT at our institution during the study period, 174 returned for follow-up and 127 had repeat echocardiography. Baseline clinical characteristics and survival were similar among those who did or did not return for follow-up. In paired analyses, New York Heart Association (NYHA) class (-0.56 +/- 0.07, p < 0.0001), ejection fraction (EF, 6.3 +/- 0.7%, P < 0.0001), LV dimension (-2.7 +/- 0.6 mm, P < 0.0001), pulmonary artery systolic pressure (PASP, -4.6 +/- 1.3 mm Hg, P = 0.0007), and MR severity grade (-0.20 +/- 0.05, P = 0.0002) improved after CRT. Survival after CRT was associated with decrease in NYHA class (risk ratio [RR]= 0.43, P = 0.0004), increase in EF (RR = 0.94, P = 0.02), and decrease in PASP (RR = 0.96, P = 0.03). Change in EF and NYHA class were correlated (r = -0.46, P < 0.0001) and, adjusting for this covariance, change in NYHA (P = 0.04) but not EF (P = 0.12) was associated with improved survival., Conclusion: Patients who experience improved symptoms, ventricular function, and/or hemodynamics have better survival after CRT. These data enhance understanding of the relationship between CRT clinical response and survival benefit in clinical practice.

Background: Recent advisories and recalls of pacemakers and implantable cardioverter-defibrillators (ICDs) have highlighted the need for evidence-based recommendations regarding management of patients with advisory devices. In order to better facilitate decision-making when weighing the relative risks and benefits of performing generator changes in these patients, we conducted a review to assess operative complication rates., Methods: We reviewed generator changes performed between 2000 and 2005 at the Mayo Clinic-Rochester, including a total of 732 change-outs consisting of 570 done for elective replacement indicators (ERI) and 162 for manufacturer advisories or recalls. Complications included all those requiring reoperation, occurring within a 60-day period postoperatively and directly attributable to the generator change. These included infection requiring device excision, hematoma requiring evacuation, and incisional dehiscence requiring reclosure., Results: Operation-associated complications requiring intervention were noted in 9 patients, or 1.24% of our population. Of these nine complications, eight occurred among patients receiving pulse generator replacement for ERI (1.40%) and one occurred in a patient receiving replacement for a manufacturer advisory or recall (0.62%). Complications included 5 infections, 3 hematomas, and 1 incisional dehiscence., Conclusions: Generator replacement is not a benign procedure and associated risks must be weighed in the context of other variables when making management choices in patients with advisory or recall devices.

Introduction: Our objective was to determine features of ventricular tachyarrhythmias triggering appropriate implantable cardioverter-defibrillator (ICD) interventions in hypertrophic cardiomyopathy (HCM)., Methods and Results: The study cohort was 68 high-risk HCM patients who received ICDs for primary sudden cardiac death prevention from 1995 to 2003. All episodes of sustained ventricular tachyarrhythmias identified by stored intracardiac electrograms were analyzed. Nine patients had 51 episodes of sustained ventricular tachyarrhythmic events that required device therapy (mean follow-up, 3.4 +/- 2.2 years; cumulative event rate, 3.2% per year): five had 47 episodes of monomorphic ventricular tachycardia (VT); four each had one episode of ventricular fibrillation (VF). Sinus tachycardia or atrial fibrillation was the initiating rhythm in five of nine patients and in 43 of 51 episodes of events. Of the 17 episodes of monomorphic VT detected in the VT zone, 16 (94%) were terminated by antitachycardia pacing. Thirty episodes of monomorphic VT were detected in the VF zone and were terminated by defibrillation., Conclusion: Sustained monomorphic VT is common in a high-risk cohort with HCM. Sinus tachycardia is often the initiating rhythm, suggesting that high sympathetic drive may be proarrhythmic when a susceptible substrate is present. Antitachycardia pacing is highly effective in terminating VT in this patient population.

Background: Perforation during catheter procedures in either the atrium or ventricle is relatively uncommon, but potentially fatal if tamponade ensues. This study analyzes the occurrence and outcomes of cardiac perforation during catheter-based radiofrequency ablation procedures in the left atrium., Methods: All patients with a periprocedure perforation who have undergone radiofrequency ablation for atrial fibrillation (AF) or tachycardia were included., Results: Of 632 procedures performed from January 1999 to October 2004, 15 (2.4%) were complicated by perforation requiring pericardiocentesis. The perforation site was left atrium in 9 (60.0%), right atrium in 1 (6.7%), and right ventricle in 5 (33.3%). Intracardiac echocardiography was used in 13 (86.7%) and revealed an effusion before overt instability in 11 (73.3%). Thirteen (86.7%) patients developed a blood pressure <60 mmHg. The pressure stabilized in all patients after pericardiocentesis (hypotension to intervention: 10.1 +/- 5.1 minutes). The total blood volume removed was 848 +/- 880 mL (left atrium/right atrium: 1,074 +/- 1,002 vs right ventricle: 396 +/- 266, P = 0.168). Two patients required surgery to close left atrium dome perforations. The ablation was completed in 7 (46.7%) patients. Ten (66.7%) later developed early reoccurrence of AF. All patients were neurologically intact at hospital discharge. During a 1.5 +/- 1.1 year follow-up, AF was eliminated (n = 4) or controlled (n = 1) in 5 (71.4%) patients with complete procedures, and 2 (20.0%) patients underwent successful repeat ablation., Conclusion: The incidence of perforation during ablation of the left atrium is low. Most perforations occur in the left atrium; however, few require surgical closure. Although less than with uncomplicated procedures, the majority of patients with complete ablations achieve long-term elimination of AF.

Aneurysms of the left atrial appendage are exceedingly rare. Patients most commonly present with atrial tachyarrhythmias and thromboembolism. Resection of the aneurysm is usually curative. We present a case report of a 60-year-old female with a long-standing history of atrial arrhythmias found to have a large left atrial appendage aneurysm with additional bi-atrial enlargement and a family history of atrial arrhythmias. The patient was successfully treated with resection of the aneurysm and a Cox-Maze III procedure.