Pulsed Field vs Conventional Thermal Ablation for Paroxysmal Atrial Fibrillation: Recurrent Atrial Arrhythmia Burden.

BACKGROUND: The ADVENT randomized trial revealed no significant difference in 1-year freedom from atrial arrhythmias (AA) between thermal (radiofrequency/cryoballoon) and pulsed field ablation (PFA). However, recent studies indicate that the postablation AA burden is a better predictor of clinical outcomes than the dichotomous endpoint of 30-second AA recurrence. OBJECTIVES: The goal of this study was to determine: 1) the impact of postablation AA burden on outcomes; and 2) the effect of ablation modality on AA burden. METHODS: In ADVENT, symptomatic drug-refractory patients with paroxysmal atrial fibrillation underwent PFA or thermal ablation. Postablation transtelephonic electrocardiogram monitor recordings were collected weekly or for symptoms, and 72-hour Holters were at 6 and 12 months. AA burden was calculated from percentage AA on Holters and transtelephonic electrocardiogram monitors. Quality-of-life assessments were at baseline and 12 months. RESULTS: From 593 randomized patients (299 PFA, 294 thermal), using aggregate PFA/thermal data, an AA burden exceeding 0.1% was associated with a significantly reduced quality of life and an increase in clinical interventions: redo ablation, cardioversion, and hospitalization. There were more patients with residual AA burden <0.1% with PFA than thermal ablation (OR: 1.5; 95% CI: 1.0-2.3; P = 0.04). Evaluation of outcomes by baseline demographics revealed that patients with prior failed class I/III antiarrhythmic drugs had less residual AA burden after PFA compared to thermal ablation (OR: 2.5; 95% CI: 1.4-4.3; P = 0.002); patients receiving only class II/IV antiarrhythmic drugs pre-ablation had no difference in AA burden between ablation groups. CONCLUSIONS: Compared with thermal ablation, PFA more often resulted in an AA burden less than the clinically significant threshold of 0.1% burden. (The FARAPULSE ADVENT PIVOTAL Trial PFA System vs SOC Ablation for Paroxysmal Atrial Fibrillation [ADVENT]; NCT04612244).

Comparison of cerebral safety following atrial fibrillation using pulsed field and thermal ablation: Results of the Neurological Assessment Subgroup in the ADVENT Trial.

BACKGROUND: Atrial fibrillation (AF) ablation carries the risk of silent cerebral event (SCE) and silent cerebral lesion (SCL). Though "silent," these may have long-term clinical implications and are challenging to study as post-procedural MRI is not standard-of-care. OBJECTIVE: The neurological assessment subgroup (NAS) of ADVENT compared cerebral effects of pulsed field ablation (PFA) to standard-of-care thermal ablation. METHODS: The NAS included consecutive randomized PFA and thermal ablation patients who received post-procedural brain MRI 12-48 hours post-ablation. Patients with apparent SCE or SCL findings underwent a modified Rankin Scale (mRS) assessment. MRI images were subsequently reviewed by a blinded Brain Imaging Core Laboratory. RESULTS: In total, 77 patients with paroxysmal AF were enrolled at 6 centers; 71 had analyzable scans (34 PFA; 37 thermal ablation). Through individual center review, 6 PFA and 4 thermal scans were identified as SCE/SCL positive, of which, 3 PFA and 0 thermal SCE/SCL findings were confirmed by a blinded core laboratory. MRI findings revealed one patient with 2-4mm SCEs, one patient with a 3mm SCE, and one patient with 2 SCLs (5.5mm and 11mm). All mRS and NIHSS scores were 0 prior to discharge and at 90-day follow-up. There were only two neurological safety events (1 TIA (PFA) and 1 stroke (thermal) in the ADVENT study, neither of which was part of the NAS. CONCLUSIONS: The ADVENT trial provides the first prospective, randomized data on the cerebral impact of PFA and thermal ablation of AF. Incidence of SCE/SCLs following ablation in the NAS was low.

Experiences Implementing a Suite of Decision Aids for Implantable Cardioverter Defibrillators: Qualitative Insights From the DECIDE-ICD Trial.

BACKGROUND: Shared decision making (SDM) is gaining importance in cardiology, including Centers for Medicare & Medicaid Services (CMS) reimbursement policies requiring documented SDM for patients considering primary prevention implantable cardioverter defibrillators. The DECIDE-ICD Trial (Decision Support Intervention for Patients offered implantable Cardioverter-Defibrillators) assessed the implementation and effectiveness of patient decision aids (DAs) using a stepped-wedge design at 7 sites. The purpose of this subanalysis was to qualitatively describe electrophysiology clinicians' experience implementing and using the DAs. METHODS: This included semi-structured individual interviews with electrophysiology clinicians at participating sites across the US, at least 6 months following conversion into the implementation phase of the trial (from June 2020 through February 2022). The interview guide was structured according to the RE-AIM (Reach, Effectiveness, Adoption, Implementation and Maintenance [implementation evaluation model]) framework, assessing clinician experiences, which can impact implementation domains, and was qualitatively assessed using a mixed inductive/deductive method. RESULTS: We completed 22 interviews post-implementation across all 7 sites. Participants included both physicians (n=16) and other clinicians who counsel patients regarding treatment options (n=6). While perception of SDM and the DA were positive, participants highlighted reasons for uneven delivery of DAs to appropriate patients. The CMS mandate for SDM was not universally viewed as associating with patients receiving DA's, but rather (1) logistics of DA delivery, (2) perceived effectiveness in improving patient decision-making, and (3) match of DA content to current patient populations. Remaining tensions include the specific trial data used in DAs and reconciling timing of delivery with when patients are actively making decisions. CONCLUSIONS: Clinicians charged with delivering DAs to patients considering primary prevention implantable cardioverter defibrillators were generally supportive of the tenets of SDM, and of the DA tools themselves, but noted several opportunities to improve the reach and continued use of them in routine care. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique Identifier: NCT03374891.

Outcome of MRI in Patients with Nonconditional Devices with Mismatch between Manufacturer of Leads and Generator.

In a series of 35 MRI examinations with non-MRI-conditional devices with a mismatch between the manufacturer of the device generators and leads, there were no adverse events.

Prospective evaluation of the effect of smartphone electrocardiogram usage on anticoagulant medication compliance.

PURPOSE: Compliance with anticoagulation treatment for atrial fibrillation is highly variable. Smartphone electrocardiograms that allow patients to have greater insight into their arrhythmia burden may improve anticoagulant compliance. METHODS: Patients were enrolled if they had atrial fibrillation with a CHA2DS2-VASc score of 2 or more, were eligible for anticoagulation and had a smartphone. Participants were randomly assigned to receive a smartphone electrocardiogram (AliveCor Kardia) to record their electrocardiograms 5 times/week or to the control group. All patients received 6 months of anticoagulant (apixaban) dispensed as 1-month pre-loaded pill boxes. RESULTS: A total of 100 patients were enrolled from July 2017 to August 2019, but 5 patients in the monitor arm and 1 in the control arm withdrew prematurely. The monitor and control groups did not differ in age, gender, CHA2DS2-VASc score, or comorbidities. Median medication compliance was 99.7%, with nonsignificantly greater compliance in the monitor group (100%) than in the control group (99.7%) (p-value = 0.247). There was also no significant difference between missing any dose and use/nonuse of the smartphone monitor (48.9% vs. 55.1%; p-value = 0.692). Mean monitor compliance was 86.8% ± 14.0% with an average of 4.34 recorded electrocardiograms per week. Monitor group patients with perfect medication compliance had significantly higher monitor compliance than those patients who missed doses (median 95.3% vs 86.7%; p-value = 0.02). CONCLUSIONS: In a study population with higher-than-expected medication compliance, the use of smartphone electrocardiogram did not demonstrate an improvement in medication compliance as compared to usual care. Greater monitor compliance was associated with greater medication compliance. CLINICAL TRIAL REGISTRATION: BOAT-OAR ClinicalTrials.gov number, NCT03515083.

Comparative outcomes of vascular access closure methods following atrial fibrillation/flutter catheter ablation: insights from VAscular Closure for Cardiac Ablation Registry.

PURPOSE: This registry compared the safety and efficacy of vascular closure device Perclose (PC) with figure-of-eight stitch (Fo8) and manual compression (MC) following catheter ablation of atrial fibrillation/flutter. METHODS: VAscular Closure for Cardiac Ablation Registry (VACCAR) is a prospective, observational registry that assessed the time to hemostasis (TTH), time to ambulation (TTA), length of stay (LOS), complications, patient-reported outcomes, and pain medication use. RESULTS: A total of 434 patients (mean age 64.0±11.0 years; 38% female; 94.9% white) were enrolled between October 2017 and May 2019: 156 in MC, 203 in Fo8, and 75 in the PC group. Median TTH was significantly reduced in the PC and Fo8 group at 7 and 9 min respectively vs. the MC group at 20 min (p<0.001). Median TTA was significantly reduced in both the PC and Fo8 group at 2.2 h vs. the MC group at 6.5 h (p<0.001 for both). Median LOS for the PC group was significantly reduced at 27.5 h compared to the MC and Fo8 group at 29 h (p<0.01). A higher proportion of same-day discharges were noted in the PC and Fo8 groups at 14 (18.7%) and 25 (12.3%), respectively, compared to 5 (3.2%) in the MC group (p<0.01 for all). There was no significant difference in complications between the three groups. CONCLUSIONS: Both PC and Fo8 are safe with improved TTH, TTA, LOS, and a higher number of same-day discharges compared to MC.

Outpatient Management of Heart Failure During the COVID-19 Pandemic After Adoption of a Telehealth Model.

OBJECTIVES: This study sought to determine whether the increased use of telehealth was associated with a difference in outcomes for outpatients with heart failure. BACKGROUND: The COVID-19 pandemic led to dramatic changes in the delivery of outpatient care. It is unclear whether increased use of telehealth affected outcomes for outpatients with heart failure. METHODS: In March 2020, a large Midwestern health care system, encompassing 16 cardiology clinics, 16 emergency departments, and 12 hospitals, initiated a telehealth-based model for outpatient care in the setting of the COVID-19 pandemic. A propensity-matched analysis was performed to compare outcomes between outpatients seen in-person in 2018 and 2019 and via telemedicine in 2020. RESULTS: Among 8,263 unique patients with heart failure with 15,421 clinic visits seen from March 15 to June 15, telehealth was employed in 88.5% of 2020 visits but in none in 2018 or 2019. Despite the pandemic, more outpatients were seen in 2020 (n = 5,224) versus 2018 and 2019 (n = 5,099 per year). Using propensity matching, 4,541 telehealth visits in 2020 were compared with 4,541 in-person visits in 2018 and 2019, and groups were well matched. Mortality was similar for telehealth and in-person visits at both 30 days (0.8% vs 0.7%) and 90 days (2.9% vs 2.4%). Likewise, there was no excess in hospital encounters or need for intensive care with telehealth visits. CONCLUSIONS: A telehealth model for outpatients with heart failure allowed for distanced encounters without increases in subsequent acute care or mortality. As the pressures of the COVID-19 pandemic abate, these data suggest that telehealth outpatient visits in patients with heart failure can be safely incorporated into clinical practice.

Successful Subcutaneous Defibrillator Implantation in a Pregnant Patient With Long QT Syndrome.

A 26-year-old woman with recurrent unexplained syncope in the postpartum period was diagnosed with long QT syndrome type 2. Traditional implantation of defibrillator using fluoroscopy became contraindicated after she again became pregnant prior to device implantation. A subcutaneous defibrillator was successfully implanted in the second trimester, after a multidisciplinary evaluation. (Level of Difficulty: Intermediate.).

Change in hospitalization rates following transcatheter left atrial appendage occlusion.

Introduction: Left atrial appendage occlusion (LAAO) is recommended in patients with non-valvular atrial fibrillation (AF) who have contraindications to or are intolerant of long-term oral anticoagulants (OAC), but its impact on hospitalization rates has not been well described. The objective of our study is to describe the incidence of all-cause, bleeding-related, and thrombosis-related hospitalizations before and after LAAO. Material and methods: We used the Nationwide Readmission Database to include patients aged ≥ 18 years with a diagnosis of AF who underwent transcatheter LAAO during the months of February-November in each year between 2016 and 2018. Patients who died during the index procedure or had missing length of hospital stay or mortality information were excluded. Results: A total of 27,633 patients were included (median age: 77 years, 41% female) with an average pre- and post-LAAO monitoring period of 6.5 and 5.5 months respectively. Of these, 10,808 (39.1%) patients had one or more admissions prior to the procedure compared to 7,196 (26.0%) after the procedure. There was a 26% reduction in incidence of all-cause admissions (rate ratio (RR) = 0.74, 95% confidence interval (CI): 0.71-0.76; p < 0.001), 49% reduction in bleeding-related admissions (RR = 0.51, 95% CI: 0.48-0.55; p < 0.001), and 71% reduction in thrombosis-related readmissions (RR = 0.29, 95% CI: 0.26-0.33; p < 0.001) after LAAO. Conclusions: In a contemporary, nationally representative dataset, we found that LAAO is associated with a significant decrease in all-cause, bleeding-related, and thrombosis-related admissions. These findings lend support to the current use of transcatheter LAAO in clinical practice for patients with contraindications to OAC and/or at high risk of bleeding.

A multicenter trial of a shared DECision Support Intervention for Patients offered implantable Cardioverter-DEfibrillators: DECIDE-ICD rationale, design, Medicare changes, and pilot data.

Shared decision making (SDM) facilitates delivery of medical therapies that are in alignment with patients' goals and values. Medicare national coverage decision for several interventions now includes SDM mandates, but few have been evaluated in nationwide studies. Based upon a detailed needs assessment with diverse stakeholders, we developed pamphlet and video patient decision aids (PtDAs) for implantable cardioverter/defibrillator (ICD) implantation, ICD replacement, and cardiac resynchronization therapy with defibrillation to help patients contemplate, forecast, and deliberate their options. These PtDAs are the foundation of the Multicenter Trial of a Shared Decision Support Intervention for Patients Offered Implantable Cardioverter-Defibrillators (DECIDE-ICD), a multicenter, randomized trial sponsored by the National Heart, Lung, and Blood Institute aimed at understanding the effectiveness and implementation of an SDM support intervention for patients considering ICDs. Finalization of a Medicare coverage decision mandating the inclusion of SDM for new ICD implantation occurred shortly after trial initiation, raising novel practical and statistical considerations for evaluating study end points. METHODS/DESIGN: A stepped-wedge randomized controlled trial was designed, guided by the RE-AIM (Reach, Effectiveness, Adoption, Implementation, Maintenance) planning and evaluation framework using an effectiveness-implementation hybrid type II design. Six electrophysiology programs from across the United States will participate. The primary effectiveness outcome is decision quality (defined by knowledge and values-treatment concordance). Patients with heart failure who are clinically eligible for an ICD are eligible for the study. Target enrollment is 900 participants. DISCUSSION: Study findings will provide a foundation for implementing decision support interventions, including PtDAs, with patients who have chronic progressive illness and are facing decisions involving invasive, preference-sensitive therapy options.

Cryoballoon ablation of pulmonary veins for persistent atrial fibrillation: Results from the multicenter STOP Persistent AF trial.

BACKGROUND: Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation to treat patients with symptomatic drug-refractory atrial fibrillation (AF). OBJECTIVE: The purpose of this study was to assess the safety and efficacy of PVI using the cryoballoon catheter to treat patients with persistent AF. METHODS: STOP Persistent AF (ClinicalTrials.gov Identifier: NCT03012841) was a prospective, multicenter, single-arm, Food and Drug Administration-regulated trial designed to evaluate the safety and efficacy of PVI-only cryoballoon ablation for drug-refractory persistent AF (continuous episodes <6 months). The primary efficacy endpoint was 12-month freedom from ≥30 seconds of AF, atrial flutter (AFL), or atrial tachycardia (AT) after a 90-day blanking period. The prespecified performance goals were set at >40% and <13% for the primary efficacy and safety endpoints, respectively. Secondary endpoints assessed quality of life using the AFEQT (Atrial Fibrillation Effect on Quality of Life) and SF (Short Form)-12 questionnaires. RESULTS: Of 186 total enrollments, 165 subjects (70% male; age 65 ± 9 years; left atrial diameter 4.2 ± 0.6 cm; body mass index 31 ± 6) were treated at 25 sites in the United States, Canada, and Japan. Total procedural, left atrial dwell, and fluoroscopy times were 121 ± 46 minutes, 102 ± 41 minutes, and 19 ± 16 minutes, respectively. At 12 months, the primary efficacy endpoint was 54.8% (95% confidence [CI] 46.7%-62.1%) freedom from AF, AFL, or AT. There was 1 primary safety event, translating to a rate of 0.6% (95% CI 0.1%-4.4%). AFEQT and SF-12 assessments demonstrated significant improvements from baseline to 12 months postablation (P <.001). CONCLUSION: The STOP Persistent AF trial demonstrated cryoballoon ablation to be safe and effective in treating patients with drug-refractory persistent AF characterized by continuous AF episodes <6 months.

Outcomes using a single tapered dilator for Micra leadless pacemaker implant.

OBJECTIVES: Comparison of outcomes, device deployment time (DT), and total time (TT) using a single tapered Coons dilator versus sequential serial dilation for implantation of the Micra leadless pacemaker. BACKGROUND: Micra leadless pacemaker placement requires a 23 French Micra introducer sheath (MIS) for percutaneous delivery. We sought to evaluate outcomes with use of a single tapered Coons dilator (CD) versus sequential serial dilatation (SD) method to facilitate insertion of the Micra introducer sheath. METHODS: 35 patients were included in the SD arm and 49 in the CD arm. DT and TT were recorded in minutes and cost in dollars. Analysis was performed using independent t-test between two groups and one-way ANOVA to evaluate inter-operator variability in the CD arm. RESULTS: Both DT and TT were significantly lower for the CD arm (15.1 ± 5.1 vs 23.5 ± 9.3, p < 0.0005 and 29.9 ± 14 vs 39.3 ± 13.5 min, p = 0.000374; respectively). The cost was also significantly lower using a CD versus SD. There was no inter-operator variability in the CD arm between 6 operators (p = 0.177 for DT and p = 0.304 for TT). No complications occurred in the SD arm. There were 3 vascular access site complications in the CD arm, all of which occurred early in the operator's experience. CONCLUSION: Coons dilator is an efficient and cost-effective method for vascular dilatation to facilitate Micra leadless pacemaker insertion. Rate of complications is low and expected to improve with greater experience.

Safety and Clinical Impact of MRI in Patients with Non-MRI-conditional Cardiac Devices.

PURPOSE: To explore the safety and clinical utility of MRI in participants with non-MRI-conditional cardiac implantable electronic devices, by establishing the Patient Registry of Magnetic Resonance Imaging in Non-Approved DEvices (PROMeNADe). MATERIALS AND METHODS: From September 2015 to June 2019, 532 participants (211 women) with a mean age of 69 years ± 14 (standard deviation) were enrolled prospectively in the PROMeNADe registry (ClinicalTrials.gov identifier: NCT03081364) and underwent a total of 608 MRI examinations (61 cardiac MRI examinations). All participants had device interrogations performed before and after each MRI. Pacemaker-dependent patients received asynchronous pacing. Patients with an implantable cardioverter defibrillator (ICD) had tachycardia therapies disabled during the MRI. An electrophysiology nurse monitored participants for any hemodynamic or rhythm abnormalities. Referring physicians were surveyed regarding the clinical utility of the MRI. Standard descriptive analyses included summary statistics with percentages and means. RESULTS: Cardiac devices included pacemakers (46%), ICDs (30%), cardiac resynchronization therapy (CRT) pacemakers (4%), and CRT defibrillators (17%), as well as abandoned leads (2%). Pacemaker-dependent patients comprised 27% of all MRI examinations. There were no patient- or device-related complications. Clinical utility surveys of MRI examinations were completed by 150 physicians. According to the survey responses, these MRI examinations changed the suspected diagnosis 25% of the time and changed suspected prognosis in 26% of participants, with planned medical or surgical treatment being changed 42% of the time. CONCLUSION: This registry demonstrates that MRI examinations, including thoracic MRI examinations, can be performed safely in patients who have non-MRI-conditional devices, in pacemaker-dependent patients with ICDs, and in patients with abandoned leads. These MRI examinations can have a substantial impact on patient care, justifying the extensive resources used to perform them.Supplemental material is available for this article.© RSNA, 2020See also the commentary by Peshock in this issue.

Prevalence and predictors of complications of radiofrequency catheter ablation for atrial fibrillation.

INTRODUCTION: Up to 6% of patients experience complications after radiofrequency catheter ablation (RFA) of atrial fibrillation (AF). The purpose of this study is to determine the prevalence and predictors of periprocedural complications after RFA for AF. METHODS AND RESULTS: The subjects were 1,295 consecutive patients (age = 60 ± 10 years) who underwent RFA (n = 1,642) for paroxysmal (53%) or persistent AF (47%) from January 2007 to January 2010. A complication occurred in 57 patients (3.5%); a vascular access complication in 31 (1.9%); pericardial tamponade in 20 (1.2%); a thromboembolic event in 4 (0.2%); deep venous thrombosis in 1 (<0.01%); and pulmonary vein stenosis in 1 patient (<0.01%). There were no procedure-related deaths. On multivariate analysis, female gender (OR = 2.27; ±95% CI: 1.31-2.57, P < 0.01) and procedures performed in July or August (OR = 2.10; ±95% CI: 1.16-3.80, P = 0.01) were independent predictors of any complication. For vascular complications, treatment with clopidogrel (OR = 4.40; ±95% CI: 1.43-13.53, P = 0.01), female gender (OR = 3.65; ±95% CI: 1.72-7.75, P < 0.01) and performing RFA in July or August (OR = 2.71; ±95% CI: 1.25-5.87, P = 0.01) were independent predictors. The only predictor of cardiac tamponade was prior RFA (OR = 3.32; ±95% CI: 0.95-11.61; P < 0.05). CONCLUSION: Prevalence of perioperative complications for RFA of AF is 3.5% and vascular access complications constitute the majority. The need for clopidogrel therapy should be carefully considered prior to RFA. At teaching institutions close supervision should be exercised during vascular access early in the year. Improvements in ablation technology and elimination of the need for repeat procedures may decrease the risk of pericardial tamponade.

Mapping and ablation of epicardial idiopathic ventricular arrhythmias from within the coronary venous system.

BACKGROUND: The prevalence of epicardial idiopathic ventricular arrhythmias that can be ablated from within the coronary venous system (CVS) has not been described. METHODS AND RESULTS: In a consecutive group of 189 patients with idiopathic ventricular arrhythmias referred for ablation, the site of origin (SOO) of ventricular tachycardia and/or premature ventricular contractions was determined by activation mapping and pace mapping. Mapping was performed within the CVS if endocardial mapping did not reveal an SOO. Venography of the CVS and coronary angiography were performed before ablation in the CVS. In 27 of 189 patients (14%+/-5%; 95% confidence interval), the SOO of the ventricular arrhythmia was identified from within the coronary venous system, either in the great cardiac vein (n=26) or the middle cardiac vein (n=1). The mean activation time at the SOO was -29+/-8 ms. Twenty of 27 patients (74%) underwent successful ablation within the CVS. Epicardial ventricular arrhythmias displayed a broader R wave in V(1) compared with arrhythmias in the control group (85 ms [interquartile range, 40] versus 65 ms [interquartile range, 95]; P<0.01). Two patients had recurrent premature ventricular contractions within 2 weeks after ablation, and no recurrences occurred in the remaining patients during a median follow-up of 13 months (range, 25). In the 7 patients with unsuccessful ablation, failure was because the ablation catheter could not be advanced to the SOO within the great cardiac vein (n=4), inadequate power delivery at the SOO (n=1), proximity to the phrenic nerve (n=1), or proximity of the SOO to a major coronary artery (n=1). Transcutaneous epicardial ablation was effective in 1 of 2 patients in whom it was attempted. CONCLUSIONS: Almost 15% of idiopathic ventricular arrhythmias have an epicardial origin. ECG characteristics help to differentiate epicardial arrhythmias from endocardial ventricular arrhythmias. The SOO of epicardial arrhythmias can be ablated from within the CVS in approximately 70% of patients.

Assessment of radiofrequency ablation lesions by CMR imaging after ablation of idiopathic ventricular arrhythmias.

OBJECTIVES: To identify and characterize ablation lesions after radiofrequency (RF) catheter ablation of ventricular arrhythmias in patients without prior myocardial infarction and to correlate the ablation lesions with the amount of RF energy delivered and the clinical outcome. BACKGROUND: Visualization of RF energy lesions after ablation of ventricular arrhythmias might help to identify reasons for ablation failure. METHODS: In a consecutive series of 35 patients (19 women, age: 48 +/- 15 years, ejection fraction: 0.56 +/- 0.12) without structural heart disease who were referred for ablation of ventricular arrhythmias, cardiac magnetic resonance imaging with delayed enhancement was performed before and after ablation. Ablation lesions were sought in the post-ablation cardiac magnetic resonance images. The endocardial area, depth, and volume of the lesions were measured. Lesion size was correlated with the type of ablation catheter used and the duration of RF energy delivered. RESULTS: In 25 of 35 patients (71%), ablation lesions were identified by delayed enhancement a mean of 22 +/- 12 months after the initial ablation procedure. The mean lesion volume was 1.4 +/- 1.4 cm(3), with a mean endocardial area of 3.5 +/- 3.0 cm(2). The largest lesions (mean volume of 2.9 +/- 2.1 cm(3) with an endocardial area of 6.4 +/- 3.4 cm(2)) were identified in patients in whom the arrhythmias originated in the papillary muscles. Ablation duration correlated with lesion size (r = 0.67, p < 0.001). There was no difference in lesion volume with irrigated versus nonirrigated ablation catheters (1.0 +/- 0.73 vs. 2.0 +/- 2.1 cm(3), p = 0.09). Identification of ablation lesions in patients with a failed procedure identified the sites where ineffective RF energy lesions were created. CONCLUSIONS: RF ablation lesions can be detected long term after an ablation procedure targeting ventricular arrhythmias in patients without previous infarction. Lesion size correlates with the amount of RF energy delivered and is largest when a targeted arrhythmia originates in a papillary muscle.

Relationship between burden of premature ventricular complexes and left ventricular function.

BACKGROUND: Frequent idiopathic premature ventricular complexes (PVCs) can result in a reversible form of left ventricular dysfunction. The factors resulting in impaired left ventricular function are unclear. Whether a critical burden of PVCs can result in cardiomyopathy has not been determined. OBJECTIVE: The objective of this study was to determine a cutoff PVC burden that can result in PVC-induced cardiomyopathy. METHODS: In a consecutive group of 174 patients referred for ablation of frequent idiopathic PVCs, the PVC burden was determined by 24-hour Holter monitoring, and transthoracic echocardiograms were used to assess left ventricular function. Receiver-operator characteristic curves were constructed based on the PVC burden and on the presence or absence of reversible left ventricular dysfunction to determine a cutoff PVC burden that is associated with left ventricular dysfunction. RESULTS: A reduced left ventricular ejection fraction (mean 0.37 +/- 0.10) was present in 57 of 174 patients (33%). Patients with a decreased ejection fraction had a mean PVC burden of 33% +/- 13% as compared with those with normal left ventricular function 13% +/- 12% (P <.0001). A PVC burden of >24% best separated the patient population with impaired as compared with preserved left ventricular function (sensitivity 79%, specificity 78%, area under curve 0.89) The lowest PVC burden resulting in a reversible cardiomyopathy was 10%. In multivariate analysis, PVC burden (hazard ratio 1.12, 95% confidence interval 1.08 to 1.16; P <.01) was independently associated with PVC-induced cardiomyopathy. CONCLUSION: A PVC burden of >24% was independently associated with PVC-induced cardiomyopathy.

Risk factors for mortality in patients with cardiac device-related infection.

BACKGROUND: Because of the increased use of pacemakers and implantable cardioverter defibrillators, infection has become a complication with significant morbidity and mortality. Data on risk factors for mortality in patients with cardiac-device related infection are limited. We evaluated the prognostic significance of key clinical and echocardiographic variables in a large retrospective population of patients with cardiac-device related infection. METHODS AND RESULTS: Two hundred ten patients with cardiac-device related infection were identified at the University of Michigan between 1995 and 2006. Data were abstracted on key clinical and echocardiographic variables, treatment strategy, and 6-month outcomes. We used multivariable Cox proportional hazards models to examine clinical and echocardiographic variables that were associated with 6-month mortality. Mean age for our study population was 63+/-17 years, and 72 (44%) were women. All-cause 6-month mortality was 18% (n=37). Independent variables associated with death were systemic embolization (hazard ratio 7.11; 95% CI 2.74 to 18.48), moderate or severe tricuspid regurgitation (hazard ratio 4.24; 95% CI 1.84 to 9.75), abnormal right ventricular function (hazard ratio 3.59; 95% CI 1.57 to 8.24), and abnormal renal function (hazard ratio 2.98; 95% CI 1.17 to 7.59). Size and mobility of cardiac device vegetations were not independently associated with mortality. CONCLUSIONS: We identified several clinical and echocardiographic variables that identify patients with cardiac-device related infection who are at high-risk for mortality and may benefit from more aggressive evaluation.

Time to cardioversion of recurrent atrial arrhythmias after catheter ablation of atrial fibrillation and long-term clinical outcome.

INTRODUCTION: It is unclear whether early restoration of sinus rhythm in patients with persistent atrial arrhythmias after catheter ablation of atrial fibrillation (AF) facilitates reverse atrial remodeling and promotes long-term maintenance of sinus rhythm. The purpose of this study was to determine the relationship between the time to restoration of sinus rhythm after a recurrence of an atrial arrhythmia and long-term maintenance of sinus rhythm after radiofrequency catheter ablation of AF. METHODS AND RESULTS: Radiofrequency catheter ablation was performed in 384 consecutive patients (age 60 +/- 9 years) for paroxysmal (215 patients) or persistent AF (169 patients). Transthoracic cardioversion was performed in all 93 patients (24%) who presented with a persistent atrial arrhythmia: AF (n = 74) or atrial flutter (n = 19) at a mean of 51 +/- 53 days from the recurrence of atrial arrhythmia and 88 +/- 72 days from the ablation procedure. At a mean of 16 +/- 10 months after the ablation procedure, 25 of 93 patients (27%) who underwent cardioversion were in sinus rhythm without antiarrhythmic therapy. Among the 46 patients who underwent cardioversion at < or =30 days after the recurrence, 23 (50%) were in sinus rhythm without antiarrhythmic therapy. On multivariate analysis of clinical variables, time to cardioversion within 30 days after the onset of atrial arrhythmia was the only independent predictor of maintenance of sinus rhythm in the absence of antiarrhythmic drug therapy after a single ablation procedure (OR 22.5; 95% CI 4.87-103.88, P < 0.001). CONCLUSION: Freedom from AF/flutter is achieved in approximately 50% of patients who undergo cardioversion within 30 days of a persistent atrial arrhythmia after catheter ablation of AF.