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Multicenter FIRM Registry for AF. Introduction: The success of pulmonary vein isolation (PVI) for atrial fibrillation (AF) may be improved if stable AF sources identified by Focal Impulse and Rotor Mapping (FIRM) are also eliminated. The long-term results of this approach are unclear outside the centers where FIRM was developed; thus, we assessed outcomes of FIRM-guided AF ablation in the first cases at 10 experienced centers.

BackgroundStandard clinical practice permits the use of either single-chamber ventricular pacemakers or dual-chamber pacemakers for most patients who require cardiac pacing. Ventricular pacemakers are less expensive, but dual-chamber pacemakers are believed to be more physiologic. However, it is not known whether either type of pacemaker results in superior clinical outcomes.MethodsThe Pacemaker Selection in the Elderly study was a 30-month, single-blind, randomized, controlled comparison of ventricular pacing and dual-chamber pacing in 407 patients 65 years of age or older in 29 centers. Patients received a dual-chamber pacemaker that had been randomly programmed to either ventricular pacing or dual-chamber pacing. The primary end point was health-related quality of life as measured by the 36-item Medical Outcomes Study Short-Form General Health Survey.ResultThe average age of the patients was 76 years (range, 65 to 96), and 60 percent were men. Quality of life improved significantly after pacemaker implantation (P

Background: Recent studies demonstrate that women may respond more favorably to cardiac resynchronization therapy (CRT) than do men. The mechanisms remain unclear.Objectives: To describe the effects of gender on response to CRT and to explore potential mechanisms behind these differences.Methods: Data for 846 patients from the SMART-AV trial were used to evaluate the mechanisms behind the effects of gender on CRT response. Atrioventricular optimization (AVO) was performed via SmartDelay or echocardiography. Baseline and 6-month left ventricular end systolic volume index (LVESVi) were fitted to a linear regression model with gender predicting change in LVESVi and adjusted for baseline covariates significantly differing by gender. The interaction variable for AVO and gender was also assessed for its effect on change in LVESVi.Results: Baseline variables, including age, body mass index, left ventricular ejection fraction, QRS width, and severity of heart failure symptoms, were comparable between men and women. Women had a higher incidence of left bundle branch block conduction and nonischemic cardiomyopathy and exhibited greater reductions in LVESVi even after adjustment for these differences (13.4 mL/m(2) vs 8.5 mL/m(2); P = .002). In addition, women had greater percentages of biventricular pacing and appeared to derive greater reductions in left ventricular volume with AVO than did men.Conclusions: Women demonstrated greater reductions in LVESVi with CRT than did men. These observations are not explained by differences in baseline characteristics. Greater degrees of biventricular pacing and enhanced response to AVO in women may partly explain the reason for the gender effect on CRT response. [ABSTRACT FROM AUTHOR]

Background: Premature ventricular contractions (PVCs) commonly coexist with cardiomyopathy. Recently, PVCs have been identified as a possible cause of cardiomyopathy. We developed a PVC-induced cardiomyopathy animal model using a novel premature pacing algorithm to assess timeframe and reversibility of this cardiomyopathy and examine the associated histopathologic abnormalities.Methods and Results: Thirteen mongrel dogs were implanted with a specially programmed pacemaker capable of simulating ventricular extrasystoles. Animals were randomly assigned to either 12 weeks of bigeminal PVCs (n = 7) or no PVCs (control, n = 6). Continuous 24-hour Holter monitoring corroborated ventricular bigeminy in the PVC group (PVC, 49.8% versus control, < 0.01%; P<0.0001). After 12 weeks, only the PVC group had cardiomyopathy, with a significant reduction in left ventricular ejection fraction (PVC, 39.7 ± 5.4% versus control, 60.7 ± 3.8%; P < 0.0001) and an increase in left ventricular end-systolic dimension (PVC, 33.3 ± 3.5 mm versus control, 23.7 ± 3.6 mm; P < 0.001). Ventricular effective refractory period showed a trend to prolong in the PVC group. PVC-induced cardiomyopathy was resolved within 2 to 4 weeks after discontinuation of PVCs. No inflammation, fibrosis, or changes in apoptosis and mitochondrial oxidative phosphorylation were observed with PVC-induced cardiomyopathy.Conclusions: This novel PVC animal model demonstrates that frequent PVCs alone can induce a reversible form of cardiomyopathy in otherwise structurally normal hearts. PVC-induced cardiomyopathy lacks gross histopathologic and mitochondrial abnormalities seen in other canine models of cardiomyopathy. [ABSTRACT FROM AUTHOR]

Background: The need for pacing support in typical ICD patients is unknown.Objective: This study sought to determine whether atrial pacing with ventricular backup pacing is equivalent to ventricular backup pacing only in implantable cardioverter-defibrillator (ICD) patients.Methods: We randomized 1,030 patients from 84 sites with indications for ICDs, with sinus rhythm, and without symptomatic bradycardia to atrial pacing with ventricular backup at 60 beats/min (518) or ventricular backup pacing at 40 beats/min (512). The primary end points were time to death, heart failure hospitalization (HFH), and heart failure-related urgent care (HFUC).Results: Follow-up was 2.4 ± 0.8 years when the trial was stopped for futility. There were 355 end point events (103 deaths, 252 HFH/HFUC) in 194 patients favoring ventricular backup pacing (event-free rate 77.7% vs. 80.3% for atrial pacing at 30 months; hazard ratio 1.14, upper confidence bound 1.59, prespecified noninferiority threshold 1.21), therefore equivalence between pacing arms was not demonstrated. Overall HFH/HFUC rates were slightly higher during atrial pacing (event-free rate 85.4% vs. 86.4% for ventricular backup pacing). Exploratory analyses revealed that the difference in HFH/HFUC rates was largely seen in patients with a PR interval ≥230 ms. There were no differences between groups for atrial fibrillation, ventricular tachycardia/ventricular fibrillation, quality of life, or echocardiographic measurements. Fewer patients in the atrial pacing group were reported to develop an indication for bradycardia pacing (3.7% vs. 7.3%, P = .0053).Conclusion: Equivalence between atrial pacing and ventricular backup pacing only could not be demonstrated.Clinical Trials Identifier: NCT00281099. [ABSTRACT FROM AUTHOR]

Introduction: Implantable cardioverter-defibrillators (ICDs) are susceptible to oversensing of extracardiac signals, also known as electromagnetic interference (EMI). We report a case of an unusual source of electrical interference of only the high voltage (HV) impedance measurement in the Teligen™ ICD (Boston Scientific, St. Paul, MN, USA) caused by electrical interference from an electrosurgical generator with an electrocautery patch located in close proximity to the ICD pulse generator. Method and Results: A patient underwent an uneventful implant of a Boston Scientific Teligen™ 100 ICD. Once the device was inserted in a pocket, interrogation of the device repeatedly demonstrated HV electrode impedance measurements between <20 and 40Ω and noise only on the HV electrode. A new lead and generator were implanted without a change in the interrogation results. The erroneous measurements of HV impedance were caused by a combination of the close proximity of the electrocautery patch to the ICD generator. The continuous low-amplitude current emitted by the contact quality monitoring system of the electrosurgical cautery generator interfered with an equally weak current delivered through the lead by the device to measurement HV impedance. The Medtronic Virtuoso™ (Medtronic Inc., Minneapolis, MN, USA) ICD and the St. Jude Medical Current™ DR (St. Jude Medical, St. Paul, MN, USA) ICD were not affected by the patch due to greater magnitude of current delivered by the device to measure HV electrode impedance. Conclusion: It is important that the operator must be aware of any potential source of EMI, as it may affect the device and require immediate troubleshooting. Failure to recognize this interaction may result in inappropriate and unnecessary pulse generator replacement. (PACE 2010; 994–998) [ABSTRACT FROM AUTHOR]

Background: The exact mechanism of eliminating atrial fibrillation (AF) by catheter ablation techniques is not known. We investigated whether the extent of atrial damage conferred by radiofrequency lesions is a predictor of success after ablation, regardless of the method employed for ablation.Methods: Ninety consecutive patients with paroxysmal AF subjected to ostial-antral pulmonary vein isolation (n = 41) or circumferential (n = 49) catheter ablation were studied.Results: At 1 year follow-up, 16 out of 41 patients (39%) with ostial-antral ablation and 16 out of 49 patients (32.6%) with circumferential ablation had AF recurrences (p = 0.5). The mean duration of radiofrequency ablation lesions was statistically significantly shorter in patients with recurrence of AF compared to those with sinus rhythm 1 year after ablation (22.3 +/- 4.2 min vs. 27.2 +/- 4.5 min, respectively, p value < 0.001). Radiofrequency ablation time was inversely associated with the risk of recurrence of AF 1 year after ablation and this relationship remained even after adjustment for potential confounding factors such as age, sex, left atrial size, and type of ablation technique (ostial-antral or circumferential; HR = 0.80, 95% CI: 0.72-0.87, p < 0.001).Conclusions: Duration of radiofrequency energy delivery is an independent predictor of clinical outcome at 1 year follow-up both among patients undergoing circumferential as well as ostial-antral ablation. [ABSTRACT FROM AUTHOR]

Background: Implantable cardioverter defibrillators (ICDs) reduce mortality among appropriately selected patients who have had or are at risk for life-threatening ventricular arrhythmia. Right ventricular apical (RVA) pacing has been implicated in worsening heart failure and death. The optimal pacemaker mode for bradycardia support while minimizing unnecessary and potentially harmful RVA pacing has not been determined. Methods: The Managed Ventricular pacing vs. VVI 40 Pacing Trial (MVP) is a prospective, multicenter, randomized, single-blind, parallel, controlled clinical trial designed to establish whether atrial-based dual-chamber managed ventricular pacing mode (MVP[TM]) is equivalent or superior to back-up only ventricular pacing (VVI 40) among patients with standard indications for ICD therapy and no indication for bradycardia pacing. The MVP Trial is designed with 80% power to detect a 10% reduction in the primary endpoint of new or worsening heart failure or all-cause mortality in the MVP[TM]-treated group. Approximately 1,000 patients at 80 centers in the United States, Canada, Western Europe, and Israel will be randomized to MVP[TM] or VVI 40 pacing after successful implantation of a dual-chamber ICD. Heart failure therapies will be optimized in accordance with evidence-based guidelines. Prespecified secondary endpoints will include ventricular arrhythmias, atrial fibrillation, new indication for bradycardia pacing, health-related quality of life, and cost effectiveness. Enrollment began in October 2004 and concluded in April 2006. The study will be terminated upon recommendation of the Data Monitoring Committee or when the last patient enrolled and surviving has reached a minimum 2 years of follow-up. Conclusion: The MVP Trial will meet the clinical need for carefully designed prospective studies to define the benefits of atrial-based dual-chamber minimal ventricular pacing versus single-chamber ventricular pacing in conventional ICD patients. [ABSTRACT FROM AUTHOR]

Context: Limited information exists to direct clinical management after an implantable device has been put under advisory. A better understanding of the risks and benefits of device replacement compared with continued clinical follow-up would be helpful to clinicians.Objective: Using the tools of decision analysis, to determine the best management approach (immediate device replacement vs continued monitoring) in the setting of a device advisory.Design: A decision model was constructed to evaluate the risks and benefits associated with immediate device replacement compared with continued monitoring.Main Outcome Measures: Variables considered included indications for device implantation, anticipated course following device failure, device failure rates from the advisory ranging from 0.0001% to 1.0% per year, and device replacement mortality rates ranging from 0.10% to 1.00% per procedure. Device replacement was preferred to continued follow-up when replacement led to greater patient survival.Results: The decision to replace a recalled device depends primarily on the advisory's estimated device failure rate and the likely effects of device failure on mortality. Procedural mortality is an important secondary factor, while patient age and remaining generator life have the least influence on the decision. For pacemaker-dependent patients, advisory device failure rates exceeding 0.3% warrant device replacement in most situations. In patients with implantable cardioverter-defibrillators for primary or secondary prevention, a failure rate associated with an advisory of 3.0% is needed to favor replacement in most cases, decreasing to close to 1.0% as procedural mortality rates decrease to 0.1% or risk of fatal arrhythmias increase to near 20% per year. In cases of pacemaker implantation for non-life-threatening situations (eg, carotid sinus hypersensitivity), most device advisories do not warrant device replacement.Conclusions: The decision to replace a device under advisory is determined primarily by the incidence of device malfunction and the likely effects of device failure. This analysis provides a framework for managing recalled devices in the context of device, patient, and institutional characteristics. [ABSTRACT FROM AUTHOR]

BACKGROUND: The sequence of atrial and ventricular electrograms following termination of ventricular pacing during supraventricular tachycardia has been shown to reliably differentiate atrial tachycardia from atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT). However in patients with long HV intervals, this may be misleading due to a pseudo 'A-A-V' response. The aim of the present study is to see if inclusion of the timing of the His-bundle in the electrogram response (ER) following ventricular pacing would reliably identify the mechanism of tachycardia in patients with long HV intervals. METHODS: Eight patients (7 men) with AVNRT and underlying bundle branch block and long HV (>55 msec) intervals underwent ventricular pacing at 10-40 msec shorter than the tachycardia cycle length during SVT. The ER was classified as 'A-A-H' or 'A-H' depending on the number of atrial electrograms (A) prior to His deflection following VEP. RESULTS: The ER following ventricular pacing was classified as A-H in all 8 patients. However, using conventional classification the response was A-A-V in 5 of 8 patients due to delayed ventricular activation secondary to long HV intervals and would erroneously suggest atrial tachycardia. The ER was A-V in only 1 of 8 patients. In the remaining 2 patients the A and V electrograms were simultaneous. CONCLUSIONS: Incorporating the His-bundle in the ER following ventricular pacing would eliminate the pseudo 'A-A-V' response in patients with AVNRT and long HV intervals. Labeling the response to ventricular pacing as 'A-H' or 'A-A-H' is simple and more accurate. [ABSTRACT FROM AUTHOR]

INTRODUCTION: This study examined the relationship between dobutamine facilitation of ventricular tachyarrhythmia (VT) inducibility with programmed electrical stimulation (PES) and dobutamine stress-induced myocardial ischemia. METHODS AND RESULTS: Twenty patients with prior myocardial infarction and cardiac arrest or sustained VT but no sustained VT induced at baseline electrophysiologic testing underwent repeat PES during dobutamine infusion. Ischemia (new or worsened wall-motion abnormality) was documented by echocardiography performed in conjunction with PES. Eight patients were receiving Class I or III antiarrhythmic drugs and seven beta-blockers. Dobutamine facilitated induction of sustained VT in 16 patients (80%) and provoked ischemia in 13 patients (65%). Induction of VT was associated with ischemia in 9 patients (56%). VTs associated with ischemia were induced at higher dobutamine doses (26 +/- 11 vs 11 +/- 10 microg/kg per min, P = 0.02) than were VTs without ischemia (n = 7). Among 13 patients with provoked ischemia, 9 (69%) had VTs induced and 4 remained noninducible. The onset of ischemia occurred at the same dose as induction of VT in 5 patients and at a lower dose in 4 patients. Monomorphic VT (318 +/- 59 ms) was induced in 13 patients, of whom 8 (62%) had ischemia. The ECG morphology of VT suggested an origin in a myocardial segment that demonstrated initial viability at low doses then ischemic dysfunction at higher doses preceding VT induction in 7 (88%) of 8 patients. CONCLUSION: Dobutamine enhances inducibility of sustained VTs during PES. The temporal and anatomic association of dobutamine-induced ischemia and VT suggests that at high dobutamine doses, ischemia may contribute to ventricular arrhythmia inducibility in some patients. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Isolation of all pulmonary veins (PV) is advocated for treatment of paroxysmal atrial fibrillation (PAF). However, the superior PVs are responsible for most AF triggers, whereas the inferior PVs carry the higher risk for ablation-induced ostial stenosis. The aim of this study was to compare a superior PV isolation approach with isolation of all PVs for treatment of PAF. METHODS AND RESULTS: Fifty-two patients with PAF were randomized to either left superior pulmonary vein (LSPV) isolation followed by additional isolation of the right superior pulmonary vein (RSPV) in case of AF recurrence (group A, n = 27) or isolation of all four PVs followed by a repeat procedure in case of recurrence (group B, n = 25). At 1-year follow-up, 11 patients (41%) in group A and 8 patients (32%) in group B had AF relapse (P = 0.55). No significant differences in AF relapse were detected between groups at 3 and 12 months (log rank = 0.36, P = 0.54) and by Cox proportional hazards model analysis (P = 0.62). Nonsignificant PV stenosis was detected in two patients from group B. Total radiofrequency energy delivery and fluoroscopy and procedure times were lower in group A: 8.9 +/- 1.4 minutes vs 25.6 +/- 3.7 minutes (P < 0.001), 22.2 +/- 6.8 minutes vs 62 +/- 10.3 minutes (P < 0.001), and 131.8 +/- 26.5 minutes vs 222.2 +/- 32.3 minutes (P < 0.001), respectively. CONCLUSION: A staged superior PVs isolation approach confers equal success rates but with reduced radiofrequency energy delivery and fluoroscopy and procedure times compared to isolation of all PVs at the initial ablation attempt. [ABSTRACT FROM AUTHOR]

Implantable cardioverter defibrillators (ICDs) with dual chamber and duo! chamber rate responsive pacing may offer hemodynamic advantages for some ICD patients. Separate ICDs and DDDR pacemakers can result in device to device interactions, inappropriate shocks, and underdetection of ventricular fibrillation (VF). The objectives of this study were to compare the VF detection times between the Ventak AV II DB and the Ventak AV during high rate DDDR and DDD pacing and to test the safety of dynamic ventricular refractory period shortening. Patients receiving an ICD were randomized in a paired comparison to pacing at 150 beats/min (DDD pacing) or 175 beats/min (DDDR pacing) during ICD threshold testing to create a 'worst case scenario' for VF detection. The VF detection rate was set to 180 beats/min. and VF was induced during high rate pacing with alternating current. The device was then allowed to detect and treat VF. The induction was repeated for each patient at each programmed setting so that all patients were tested at both programmed settings. Paired analysis was performed. Patient characteristics were a mean age of 69 ± 11 years, 78% were men, coronary artery disease was present in 85%, and a mean left ventricular ejection fraction of 0.34 ± 0.11. Fifty-two episodes of VF were induced in 26 patients. Despite the high pacing rate, all VF episodes were appropriately detected. The mean VF detection time was 2.4 ± 1.0 seconds during DDD pacing and 2.9 ± 1.9 seconds during DDDH pacing (P - NS). DDD and DDDR programming resulted in appropriate detection of all episodes of VF with similar detection times despite the 'worst case scenario' tested. Delays in detection may be seen with long programmed ventricular refractory periods which shorten the VF sensing window and may be avoided with dynamic ventricular refractory period shortening. [ABSTRACT FROM AUTHOR]