Long-Term Outcomes of Resynchronization-Defibrillation for Heart Failure.

BACKGROUND: The Resynchronization-Defibrillation for Ambulatory Heart Failure Trial (RAFT) showed a greater benefit with respect to mortality at 5 years among patients who received cardiac-resynchronization therapy (CRT) than among those who received implantable cardioverter-defibrillators (ICDs). However, the effect of CRT on long-term survival is not known. METHODS: We randomly assigned patients with New York Heart Association (NYHA) class II or III heart failure, a left ventricular ejection fraction of 30% or less, and an intrinsic QRS duration of 120 msec or more (or a paced QRS duration of 200 msec or more) to receive either an ICD alone or a CRT defibrillator (CRT-D). We assessed long-term outcomes among patients at the eight highest-enrolling participating sites. The primary outcome was death from any cause; the secondary outcome was a composite of death from any cause, heart transplantation, or implantation of a ventricular assist device. RESULTS: The trial enrolled 1798 patients, of whom 1050 were included in the long-term survival trial; the median duration of follow-up for the 1050 patients was 7.7 years (interquartile range, 3.9 to 12.8), and the median duration of follow-up for those who survived was 13.9 years (interquartile range, 12.8 to 15.7). Death occurred in 405 of 530 patients (76.4%) assigned to the ICD group and in 370 of 520 patients (71.2%) assigned to the CRT-D group. The time until death appeared to be longer for those assigned to receive a CRT-D than for those assigned to receive an ICD (acceleration factor, 0.80; 95% confidence interval, 0.69 to 0.92; P = 0.002). A secondary-outcome event occurred in 412 patients (77.7%) in the ICD group and in 392 (75.4%) in the CRT-D group. CONCLUSIONS: Among patients with a reduced ejection fraction, a widened QRS complex, and NYHA class II or III heart failure, the survival benefit associated with receipt of a CRT-D as compared with ICD appeared to be sustained during a median of nearly 14 years of follow-up. (RAFT ClinicalTrials.gov number, NCT00251251.).

High-power short-duration versus low-power long-duration ablation for pulmonary vein isolation: A substudy of the AWARE randomized controlled trial.

INTRODUCTION: Pulmonary vein isolations (PVI) are being performed using a high-power, short-duration (HPSD) strategy. The purpose of this study was to compare the clinical efficacy and safety outcomes of an HPSD versus low-power, long-duration (LPLD) approach to PVI in patients with paroxysmal atrial fibrillation (AF). METHODS: Patients were grouped according to a HPSD (≥40 W) or LPLD (≤35 W) strategy. The primary endpoint was the 1-year recurrence of any atrial arrhythmia lasting ≥30 s, detected using three 14-day ambulatory continuous ECG monitoring. Procedural and safety endpoints were also evaluated. The primary analysis were regression models incorporating propensity scores yielding adjusted relative risk (RRa ) and mean difference (MDa ) estimates. RESULTS: Of the 398 patients included in the AWARE Trial, 173 (43%) underwent HPSD and 225 (57%) LPLD ablation. The distribution of power was 50 W in 75%, 45 W in 20%, and 40 W in 5% in the HPSD group, and 35 W with 25 W on the posterior wall in the LPLD group. The primary outcome was not statistically significant at 30.1% versus 22.2% in HPSD and LPLD groups with RRa 0.77 (95% confidence interval [CI]) 0.55-1.10; p = .165). The secondary outcome of repeat catheter ablation was not statistically significant at 6.9% and 9.8% (RRa 1.59 [95% CI 0.77-3.30]; p = .208) respectively, nor was the incidence of any ECG documented AF during the blanking period: 1.7% versus 8.0% (RRa 3.95 [95% CI 1.00-15.61; p = .049) in the HPSD versus LPLD group respectively. The total procedure time was significantly shorter in the HPSD group (MDa 97.5 min [95% CI 84.8-110.4)]; p < .0001) with no difference in adjudicated serious adverse events. CONCLUSIONS: An HPSD strategy was associated with significantly shorter procedural times with similar efficacy in terms of clinical arrhythmia recurrence. Importantly, there was no signal for increased harm with a HPSD strategy.

A Randomized Trial of Lenient Versus Strict Arm Instruction Post Cardiac Device Surgery (LENIENT).

BACKGROUND: Arm restriction after cardiac implantable electronic device (CIED) placement is common practice despite minimal supporting evidence. Patients receive a range of restriction recommendations of variable durations with the goal of reducing complications such as wound dehiscence, infection, lead dislodgement, or hematoma formation. These movement limitations can lead to emotional stress and anxiety, complications such as frozen shoulder, and upper extremity venous thrombosis due to immobilization. There are no published clinical trials assessing the benefits and risks of arm restrictions post-CIED implant. OBJECTIVES: The randomized trial of lenient vs strict arm and activity instruction post-CIED surgery (LENIENT trial; NCT04915261) is a single center nonblinded randomized prospective study designed to evaluate lenient compared to restrictive post-CIED care instructions. We hypothesize that there will be no significant difference in complications between the arms. METHODS/DESIGN: All patients receiving a de novo CIED or those with upgrades and revisions requiring a new lead implant will be enrolled. Subjects are enrolled in a nonblinded randomized prospective trial with 6 randomly assigned 8-month periods, during which either a lenient or restrictive postoperative activity instructions will be given to all patients. Postoperative instructions are given at the time of discharge and further reinforced by recurrent interactive voice recognition (IVR) phone calls, text messages and emails. The requirement for individual consent has been waived. The primary end point is a composite of (1) lead dislodgement, (2) frozen shoulder, (3) upper extremity venous thrombosis, (4) clinically significant hematoma, and (5) infection occurring within 52 weeks of index surgery. The study is a noninferiority trial with a sample size of 1,250 per group. DISCUSSION: This is the first large randomized clinical trial designed to establish an evidence-based postoperative standard of care for patients undergoing CIED implantation. This will improve the quality of care provided to patients and help guide implanting physicians providing postoperative care instructions. TRIAL REGISTRATION: ClinicalTrials.gov NCT04915261.

Augmented wide area circumferential catheter ablation for reduction of atrial fibrillation recurrence (AWARE) trial: Design and rationale.

BACKGROUND: Recurrence of atrial fibrillation (AF) after a pulmonary vein isolation procedure is often due to electrical reconnection of the pulmonary veins. Repeat ablation procedures may improve freedom from AF but are associated with increased risks and health care costs. A novel ablation strategy in which patients receive "augmented" ablation lesions has the potential to reduce the risk of AF recurrence. OBJECTIVE: The Augmented Wide Area Circumferential Catheter Ablation for Reduction of Atrial Fibrillation Recurrence (AWARE) Trial was designed to evaluate whether an augmented wide-area circumferential antral (WACA) ablation strategy will result in fewer atrial arrhythmia recurrences in patients with symptomatic paroxysmal AF, compared with a conventional WACA strategy. METHODS/DESIGN: The AWARE trial was a multicenter, prospective, randomized, open, blinded endpoint trial that has completed recruitment (ClinicalTrials.gov NCT02150902). Patients were randomly assigned (1:1) to either the control arm (single WACAlesion set) or the interventional arm (augmented- double WACA lesion set performed after the initial WACA). The primary outcome was atrial tachyarrhythmia (AA; atrial tachycardia [AT], atrial flutter [AFl] or AF) recurrence between days 91 and 365 post catheter ablation. Patient follow-up included 14-day continuous ambulatory ECG monitoring at 3, 6, and 12 months after catheter ablation. Three questionnaires were administered during the trial- the EuroQuol-5D (EQ-5D) quality of life scale, the Canadian Cardiovascular Society Severity of Atrial Fibrillation scale, and a patient satisfaction scale. DISCUSSION: The AWARE trial was designed to evaluate whether a novel approach to catheter ablation reduced the risk of AA recurrence in patients with symptomatic paroxysmal AF.

Characterization of arrhythmia substrate to ablate persistent atrial fibrillation (COAST-AF): Randomized controlled trial design and rationale.

BACKGROUND: Atrial low voltage area (LVA) catheter ablation has emerged as a promising strategy for ablation of persistent atrial fibrillation (AF). It is unclear if catheter ablation of atrial LVA increases treatment success rates in patients with persistent AF. OBJECTIVE: The primary aim of this trial is to assess the potential benefit of adjunctive catheter ablation of atrial LVA in addition to pulmonary vein isolation (PVI) in patients with persistent AF, when compared to PVI alone. The secondary aims are to evaluate safety outcomes, the quality of life and the healthcare resource utilization. METHODS/DESIGN: A multicenter, prospective, parallel-group, 2-arm, single-blinded randomized controlled trial is under way (NCT03347227). Patients who are candidates for catheter ablation for persistent AF will be randomly assigned (1:1) to either PVI alone or PVI + atrial LVA ablation. The primary outcome is 18-month documented event rate of atrial arrhythmia (AF, atrial tachycardia or atrial flutter) post catheter ablation. Secondary outcomes include procedure-related complications, freedom from atrial arrhythmia at 12 months, AF burden, need for emergency department visits/hospitalization, need for repeat ablation for atrial arrhythmia, quality of life at 12 and 18 months, ablation time, and procedure duration. DISCUSSION: Characterization of Arrhythmia Mechanism to Ablate Atrial Fibrillation (COAST-AF) is a multicenter randomized trial evaluating ablation strategies for catheter ablation. We hypothesize that catheter ablation of atrial LVA in addition to PVI will result in higher procedural success rates when compared to PVI alone in patients with persistent AF.

High-power, short-duration atrial fibrillation ablation compared with a conventional approach: Outcomes and reconnection patterns.

BACKGROUND: The effectiveness, safety, and pulmonary vein (PV) reconnection patterns of point-by-point high-power, short-duration (HPSD) ablation relative to conventional force-time integral (FTI)-guided strategies for atrial fibrillation (AF) ablation are unknown. OBJECTIVES: To compare 1-year freedom from atrial arrhythmia (AA), complication rates, procedural times, and PV reconnection patterns with HPSD AF AF ablation versus an FTI-guided low-power, long-duration (LPLD) strategy. METHODS: We compared consecutive patients undergoing a first ablation procedure for paroxysmal or persistent AF. The HPSD protocol utilized a power of 50 W and durations of 6-8 s posteriorly and 8-10 s anteriorly. The LPLD protocol was FTI-guided with a power of ≤25 W posteriorly (FTI ≥ 300g·s) and ≤35 W anteriorly (FTI ≥ 400g·s). RESULTS: In total, 214 patients were prospectively included (107 HPSD, 107 LPLD). Freedom from AA at 1 year was achieved in 79% in the HPSD group versus 73% in the LPLD group (p = .339; adjusted hazard ratio with HPSD, 0.67; 95% confidence interval, 0.36-1.23; p < .004 for non-inferiority). Procedure duration was shorter in the HPSD group (229 ± 60 vs. 309 ± 77 min; p < .005). Patients undergoing repeat ablation had a higher propensity for reconnection at the right PV carina in the HPSD group compared with the LPLD group (14/30 = 46.7% vs. 7/34 = 20.6%; p = .035). There were no differences in complication rates. CONCLUSION: HPSD AF ablation resulted in similar freedom from AAs at 1 year, shorter procedure times, and a similar safety profile when compared with an LPLD ablation strategy. Patients undergoing HPSD ablation required more applications at the right carina to achieve isolation, and had a significantly higher rate of right carinal reconnections at redo procedures.

Decision Support for Implantable Cardioverter-Defibrillator Replacement: A Pilot Feasibility Randomized Controlled Trial.

BACKGROUND: Decision support can help patients facing implantable cardioverter-defibrillator (ICD) replacement understand their options and reach an informed decision reflective of their preferences. OBJECTIVE: The aim of this study was to evaluate the feasibility of a decision support intervention for patients faced with the decision to replace their ICD. METHODS: A pilot feasibility randomized trial was conducted. Patients approaching ICD battery depletion were randomized to decision support intervention or usual care. Feasibility outcomes included recruitment rates, intervention use, and completeness of data; secondary outcomes were knowledge, values-choice concordance, decisional conflict, involvement in decision making, and choice. RESULTS: A total of 30 patients were randomized to intervention (n = 15) or usual care (n = 15). The intervention was used as intended, with 2% missing data. Patients in the intervention arm had better knowledge (77.4% vs 51.1%; P = .002). By 12 months, 8 of 13 (61.5%) in the intervention arm and 10 of 14 (71.4%) in the usual care arm accepted ICD replacement; 1 per arm declined (7.7% vs 7.1%, respectively). CONCLUSION: It was feasible to deliver the intervention, collect data, despite slow recruitment. The decision support intervention has the potential to improve ICD replacement decision quality.

A new electrocardiographic definition of left bundle branch block (LBBB) in patients after transcatheter aortic valve replacement (TAVR).

BACKGROUND: Current LBBB definitions cannot always distinguish LBBB from left ventricular conduction delay. Only patients with LBBB are expected to normalize with His bundle pacing. Patients who develop new LBBB immediately post transcatheter aortic valve replacement (TAVR) provide an excellent model to define electrocardiogram (ECG) features of LBBB. We sought to describe their ECG features and develop a new ECG definition of LBBB. METHODS: We screened ECGs from 264 consecutive patients who underwent TAVR at the University of Ottawa Heart Institute. Patients with a baseline QRS of ≤100 ms who developed QRS ≥120 ms immediately after TAVR were included. Two electrocardiologists reviewed all ECG independently. Baseline demographics and echocardiographic data were retrospectively collected. RESULTS: 36 patients were included in the analysis. The median age was 85.5 years (IQR, 81.8-89 years) and 52.8% were males. The minimum QRS duration was 126 ms. The median QRS axis was -18° (IQR, -40-4.5°), which is 18.5° leftward compared to the median QRS axis before TAVR. Fourteen patients (38.9%) had left axis deviation. All patients had a notched/slurred R wave in at least one lateral lead and an R wave duration of ≤20 ms in V1 when present. CONCLUSION: We developed a new ECG definition of LBBB that includes 2 novel findings: notching/slurring of the R wave in at least one lateral lead and an R wave ≤20 ms in V1. Further larger studies are warranted to confirm these findings.

Completely nonfluoroscopic catheter ablation of left atrial arrhythmias and ventricular tachycardia.

INTRODUCTION: Fluoroscopy use during catheter ablation procedures increases the cumulative lifetime radiation exposure of patients and operators, potentially leading to a higher risk of cancer and radiation-related injuries. Nonfluoroscopic ablation (NFA) has been described for supraventricular tachycardia, typical atrial flutter, paroxysmal atrial fibrillation (AF), and outflow-tract ventricular tachycardia (VT). Complete transition to NFA of more complex arrhythmias, including persistent AF, left atrial (LA) flutter, and structural VT, has not been previously described. We describe the transition to completely NFA of complex arrhythmias, including LA flutter and structural VT. The techniques, challenges, limitations, and results are described. METHODS AND RESULTS: Complex ablation procedures were performed using intracardiac echocardiography (ICE) and a three-dimensional mapping system without fluoroscopy or lead protection. Eighty consecutive patients underwent NFA (mean age, 60.1 ± 9.9 years, 70 with LA arrhythmias, 10 with VT). All cases were performed without the need for rescue fluoroscopy. There was an initial increase in procedural time for ablation of LA arrhythmias upon transitioning to NFA. However, after excluding the first 20 NFA cases to allow for operator learning, the transition to NFA was not associated with an increase in mean procedural time (229 ± 38 vs 225 ± 32 minutes; P = 0.002 for noninferiority). All procedures were completed successfully with no complications. CONCLUSIONS: NFA of most complex arrhythmias (persistent AF, LA flutter, and structural VT) is feasible, with a modest learning curve and no increase in procedural times.

Prevalence of left atrial appendage thrombus detected by transoesophageal echocardiography before catheter ablation of atrial fibrillation in patients anticoagulated with non-vitamin K antagonist oral anticoagulants.

AIMS: There is ongoing controversy about the need for routine transoesophageal echocardiography (TOE) prior to atrial fibrillation (AF) ablation. Recently, the debate was reignited by the publication of a large series of patients showing a prevalence of left atrial appendage thrombus (LAAT) on TOE of 4.4%. We sought to assess the prevalence of LAAT on TOE before AF ablation at our institution. METHODS AND RESULTS: Consecutive patients scheduled for AF ablation at our institution between January 2009 and December 2016 were included. All patients were on oral anticoagulation for at least 4 weeks prior to TOE. Transoesophageal echocardiographies were performed 3-5 days prior to scheduled AF ablation. Data were collected utilizing a prospective database. In all, 668 patients and 943 AF ablation procedures were included. Mean age was 64 ± 11 years, 72% were male, average CHADS2 score was 1.0 ± 1.0, and 72% of the patients had paroxysmal AF. At the time of ablation, 496 (53%) were on non-vitamin K antagonist oral anticoagulants (NOACs) and 447 (47%) were on Warfarin. There were three cases with LAAT (3/943, 0.3%), all of whom had persistent AF and were on Warfarin. Two patients underwent surgical ablation and the third patient did not undergo ablation. CONCLUSION: In our experience, the prevalence of LAAT in patients on anticoagulation therapy undergoing TOE before catheter ablation of AF is 0.3%, which was much lower than recently reported. None of the patients with paroxysmal AF or on NOACs were found to have LAAT. Rather than routine use of TOE prior to AF ablation, a risk-based approach should be considered.

Evaluation of a novel cardioversion intervention for atrial fibrillation: the Ottawa AF cardioversion protocol.

AIMS: Electrical cardioversion is commonly performed to restore sinus rhythm in patients with atrial fibrillation (AF), but it is unsuccessful in 10-12% of attempts. We sought to evaluate the effectiveness and safety of a novel cardioversion protocol for this arrhythmia. METHODS AND RESULTS: Consecutive elective cardioversion attempts for AF between October 2012 and July 2017 at a tertiary cardiovascular centre before (Phase I) and after (Phase II) implementing the Ottawa AF cardioversion protocol (OAFCP) as an institutional initiative in July 2015 were evaluated. The primary outcome was cardioversion success, defined as ≥2 consecutive sinus beats or atrial-paced beats in patients with implanted cardiac devices. Secondary outcomes were first shock success, sustained success (sinus or atrial-paced rhythm on 12-lead electrocardiogram prior to discharge from hospital), and procedural complications. Cardioversion was successful in 459/500 (91.8%) in Phase I compared with 386/389 (99.2%) in Phase II (P < 0.001). This improvement persisted after adjusting for age, body mass index, amiodarone use, and transthoracic impedance using modified Poisson regression [adjusted relative risk 1.08, 95% confidence interval (CI) 1.05-1.11; P < 0.001] and when analysed as an interrupted time series (change in level +9.5%, 95% CI 6.8-12.1%; P < 0.001). The OAFCP was also associated with greater first shock success (88.4% vs. 79.2%; P < 0.001) and sustained success (91.6% vs 84.7%; P=0.002). No serious complications occurred. CONCLUSION: Implementing the OAFCP was associated with a 7.4% absolute increase in cardioversion success and increases in first shock and sustained success without serious procedural complications. Its use could safely improve cardioversion success in patients with AF. CLINICAL TRIAL NUMBER: www.clinicaltrials.gov ID: NCT02192957.

The echocardiographic assessment of the right ventricle in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia compared with athletes and matched controls.

BACKGROUND: There are discrepancies in the quantitative echocardiographic criteria for the right ventricle (RV) between the revised task force criteria (TFC) for Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia (ARVC/D) and the guidelines for RV assessment endorsed by American Society of Echocardiography (ASE). Importantly, these criteria do not take into account potential adaptation of the RV to exercise. The goal of this study was to compare the revised TFC quantitative echocardiographic parameters in patients with ARVC/D, athletes and matched controls. METHODS: Echocardiographic parameters of the RV were retrospectively collected in patients who fulfilled the TFC for ARVC/D, an age- matched, sex-matched, and body surface area-matched control population, and athletes (defined as individuals who exercised for more than 7 hours per week). Patients with structural heart disease were excluded in the control and athlete groups. RESULTS: Twenty patients with ARVC/D, 11 athletes and 20 matched controls were included. There was no significant difference between ARVC/D patients and athletes with the exception of the parasternal long axis right ventricular outflow tract diameter. All parameters were significantly different between ARVC/D patients and the control group. Furthermore, when subjects were categorized into meeting 1 major revised TFC/abnormal ASE criteria or not, only ASE criteria were able to differentiate ARVC/D from control population. Both were unable to differentiate ARVC/D from athletes. CONCLUSIONS: Right ventricle quantitative echocardiographic criteria in the revised TFC are not specific for ARVC/D. Care should be taken in applying these criteria in athletes.

Efficacy and safety of driver-guided catheter ablation for atrial fibrillation: A systematic review and meta-analysis.

INTRODUCTION: Targeting localized drivers (electrical rotors or focal impulses) during catheter ablation for atrial fibrillation (AF) has been proposed as a strategy to improve procedural success. However, the strength and quality of the evidence to support this approach is unclear. METHODS AND RESULTS: Clinical studies reporting efficacy or safety outcomes of driver-guided ablation for AF were identified in Medline, Embase, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, Pubmed, and conference abstracts from major scientific meetings. Random-effects meta-analysis of efficacy outcomes from controlled studies was performed. Thirty-one reports from 30 studies were included: two randomized controlled trials, five nonrandomized controlled studies, and 23 uncontrolled studies. In controlled studies, driver-guided ablation has been associated with higher rates of acute AF termination (RR 2.08, 95% CI 1.43-3.05; P < 0.001) and increased freedom from AF/atrial tachycardia (AT) at ≥1 year (RR 1.34, 95% CI 1.05-1.70; P = 0.02). Similar rates of procedural complications have been reported between ablation strategies. Overall, current data on driver-guided ablation are predominantly from nonrandomized studies with considerable heterogeneity in mapping and ablation strategies used and in clinical outcomes reported. CONCLUSION: Pooled data on the efficacy of AF driver-guided catheter ablation suggest increased freedom from AF/AT relative to conventional strategies. However, most studies are nonrandomized and of moderate quality. Though promising data exist, there remains no conclusive evidence for the efficacy of AF driver ablation. Robust data from randomized trials are needed.

Three-year outcomes and reconnection patterns after initial contact force guided pulmonary vein isolation for paroxysmal atrial fibrillation.

BACKGROUND AND OBJECTIVE: Contact force (CF) sensing is a novel technology used for catheter ablation of atrial fibrillation (AF). We compared the single procedure success of CF-guided pulmonary vein isolation (PVI) with that of non-CF guided PVI during a 3-year (1,095 days) follow up period and analyzed the pattern of pulmonary vein (PV) reconnection. METHODS: A cohort of 167 subjects (68 CF vs. 99 non-CF) with paroxysmal AF were included in the study. Atrial arrhythmia (AA) recurrence was defined as documented AF, atrial flutter, or atrial tachycardia lasting >30 seconds and occurring after 90 days. RESULTS: Subjects in the CF group showed a statistically nonsignificant improvement in AA free survival compared to those in the non-CF group (66.2% vs. 51.5%; P value: 0.06). A greater propensity for reconnection was noted around the right-sided PVs compared to left-sided PVs related in both catheter ablation groups. For example, in the CF group 36% of right-sided segments reconnected compared to 16% of left-sided segments (P value <0.01). CONCLUSIONS: A greater propensity for reconnection was noted around the right sided PV segments in both the CF and non-CF groups. The explanation for this finding was related to greater catheter instability around the right sided veins. Further research is needed to explore the utility of a "real-time" composite indicator that includes RF energy, CF and catheter stability in predicting transmural lesion formation during catheter ablation.

Scar-based catheter ablation for persistent atrial fibrillation.

PURPOSE OF REVIEW: Percutaneous catheter ablation can be an effective treatment for paroxysmal atrial fibrillation. However, catheter ablation for the treatment of persistent atrial fibrillation or long-standing persistent atrial fibrillation is associated with success rates of 45-50% at 1 year. To address the challenge of ablating patients with persistent atrial fibrillation, several approaches have been proposed. Atrial scar-based catheter ablation is a promising strategy for ablation of persistent atrial fibrillation. RECENT FINDINGS: In this review, we outline the role of atrial scar/fibrosis in the pathophysiology of atrial fibrillation and how this encouraged clinical studies assessing the atrial substrate using scar-based mapping. We highlight current approaches to voltage mapping of atrial scar in patients with atrial fibrillation. The characteristics, techniques, and outcomes of recently published studies evaluating scar-based catheter ablation strategies for the treatment of atrial fibrillation are discussed. Finally, we explore the role of noninvasive tools such as delayed enhancement MRI to assess the atrial fibrillation substrate. SUMMARY: In summary, the optimal catheter ablation strategy for persistent atrial fibrillation remains unknown. Current data highlight the need for a better understanding of the substrate and mechanisms of arrhythmia maintenance in this population. Atrial scar-based catheter ablation has recently emerged as a promising strategy for ablation of atrial fibrillation. However, the available data have limitations that preclude definitive conclusions regarding the utility of this strategy. Further research is needed to assess the role of scar-based ablation for persistent atrial fibrillation.

Efficacy of adjunctive measures used to assist pulmonary vein isolation for atrial fibrillation: a systematic review.

PURPOSE OF REVIEW: Pulmonary vein reconnection leading to recurrence of atrial arrhythmias after pulmonary vein isolation (PVI) for atrial fibrillation remains a significant challenge. A number of adjunctive measures during PVI have been used to attempt to reduce pulmonary vein reconnection and recurrence of atrial arrhythmias. We performed a systematic review of the literature and meta-analysis of studies evaluating the efficacy of adjunctive measures used during PVI in reducing recurrent atrial arrhythmias. RECENT FINDINGS: Our literature search found four interventions that met the prespecified definition of adjunctive measure: adenosine testing post-PVI, contact force-guided PVI, pacing inexcitability of the ablation line during PVI and additional ablation based on the computed tomography thickness of the pulmonary vein-left atrial appendage ridge. Sixteen studies enrolling 3507 patients met all inclusion and exclusion criteria. PVI performed with adjunctive measures was shown to reduce the 1-year recurrence rate of atrial arrhythmias. The point estimate for the combined relative risk of atrial arrhythmia recurrence was 0.56 [95% confidence interval (CI): 0.43-0.73; P value <0.001] in the PVI with adjunctive measures group. SUMMARY: PVI for atrial fibrillation assisted by adjunctive measures results in clinically significant reduction of recurrent atrial arrhythmias. Additional research is required to assess the relative efficacy of individual or combined adjunctive strategies used during PVI for atrial fibrillation.

Radiation safety and ergonomics in the electrophysiology laboratory: update on recent advances.

PURPOSE OF REVIEW: Risks associated with exposure to ionizing radiation in patients undergoing electrophysiology procedures and interventional cardiac electrophysiologists performing these procedures are a serious concern. Strategies to reduce radiation exposure are of obvious importance. In addition, interventional cardiac electrophysiologists have to perform procedures wearing heavy lead protection for prolonged periods, making them prone to cervical and lumbar spinal injuries. RECENT FINDINGS: Recently developed technologies, such as low-exposure radiographic imaging, novel radiographic imaging protection systems, nonfluoroscopic mapping systems using image integration, and remote catheter manipulation systems have been successful in reducing ionizing radiation exposure in the electrophysiology laboratory. The efficacy and safety of these technologies are being evaluated in clinical trials. In addition, economic analyses are being performed to evaluate these novel systems. The use of nonweight-bearing radiation protection devices and ergonomic design of the electrophysiology laboratory aim to reduce the incidence of occupational injuries in interventional cardiac electrophysiologists. SUMMARY: There is need for ongoing development and evaluation of new technologies to minimize exposure to ionizing radiation during electrophysiologic procedures. In addition, ergonomic planning of the electrophysiology laboratory and training of interventional cardiac electrophysiologists are crucial to occupational injury prevention.

The role of nuclear cardiac imaging in risk stratification of sudden cardiac death.

Sudden cardiac death (SCD) represents a significant portion of all cardiac deaths. Current guidelines focus mainly on left ventricular ejection fraction (LVEF) as the main criterion for SCD risk stratification and management. However, LVEF alone lacks both sensitivity and specificity in stratifying patients. Recent research has provided interesting data which supports a greater role for advanced cardiac imaging in risk stratification and patient management. In this article, we will focus on nuclear cardiac imaging, including left ventricular function assessment, myocardial perfusion imaging, myocardial blood flow quantification, metabolic imaging, and neurohormonal imaging. We will discuss how these can be used to better understand SCD and better stratify patient with both ischemic and non-ischemic cardiomyopathy.

Effect of Applying Force to Self-Adhesive Electrodes on Transthoracic Impedance: Implications for Electrical Cardioversion.

BACKGROUND: Current guidelines disagree on the role for applying force to electrodes during electrical cardioversion (ECV) for atrial fibrillation, particularly when using self-adhesive pads. We evaluated the impact of this practice on transthoracic impedance (TTI) with varying force and in individuals with differing body mass indices (BMI). We additionally assessed whether specific prompts could improve physicians' ECV technique. METHODS: The study comprised three parts: (1) TTI was measured in 11 participants throughout the respiratory cycle and with variable force applied to self-adhesive electrodes in anteroposterior (AP) and anterolateral (AL) configurations. (2) Three participants in different BMI classes then had TTI measured with prespecified incremental force applied. (3) Ten blinded cardiology trainees simulated ECV on one participant with and without prompting (guideline reminders and force analogies) while force applied and TTI were measured. RESULTS: The AP approach was associated with 13% lower TTI than AL (P < 0.001). Strongly negative correlations were observed between force applied and TTI in the AL position, irrespective of BMI (P ≤ 0.003). In all cases, 80% of the total reduction in TTI observed was achieved with 8 kg-force (∼80 N). All prompts resulted in significantly greater force applied and modest reductions in TTI. CONCLUSIONS: Applying force to self-adhesive electrodes reduces TTI and should be considered as a means of improving ECV success. Numerically greater mean force applied with a "push-up" force analogy suggests that "concrete" cues may be useful in improving ECV technique.

Atrial fibrillation and the athletic heart.

PURPOSE OF REVIEW: Endurance exercise, despite a plethora of proven health benefits, is increasingly recognized as a potential cause of lone atrial fibrillation. Moderate exercise reduces all-cause mortality and protects against developing atrial fibrillation. However, more intense exercise regimes confer modest incremental health benefits, induce cardiac remodelling and negate some of the cardiovascular benefits of exercise. The implications of endurance exercise and athletic heart are becoming increasingly relevant as the popularity of endurance exercise has increased 20-fold within a generation. RECENT FINDINGS: An apparent dose-response relationship exists between endurance exercise and left atrial dilatation. Repeated strenuous endurance exercise overloads atria, resulting in stretch-induced 'microtears', inflammation and endocardial scarring. Although these findings are observational in humans, similar mechanisms have recently been confirmed in animal models suggesting causation. SUMMARY: Currently, it is not known whether a ceiling for endurance exercise exists, and, if so, what factors determine the threshold of harm. Although preliminary research is promising, much work remains if we are to understand the mechanisms underpinning atrial fibrillation in athletes.