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.

Catheter ablation of intramural outflow tract premature ventricular complexes: a multicentre study.

AIMS: Ablation of outflow tract ventricular arrhythmias may be limited by a deep intramural location of the arrhythmogenic source. This study evaluates the acute and long-term outcomes of patients undergoing ablation of intramural outflow tract premature ventricular complexes (PVCs). METHODS AND RESULTS: This multicenter series included patients with structurally normal heart or nonischemic cardiomyopathy and intramural outflow tract PVCs defined by: (a) ≥ 2 of the following criteria: (1) earliest endocardial or epicardial activation < 20ms pre-QRS; (2) Similar activation in different chambers; (3) no/transient PVC suppression with ablation at earliest endocardial/epicardial site; or (b) earliest ventricular activation recorded in a septal coronary vein. Ninety-two patients were included, with a mean PVC burden of 21.5±10.9%. Twenty-six patients had had previous ablations. All PVCs had inferior axis, with LBBB pattern in 68%. In 29 patients (32%) direct mapping of the intramural septum was performed using an insulated wire or multielectrode catheter, and in 13 of these cases the earliest activation was recorded within a septal vein. Most patients required special ablation techniques (one or more), including sequential unipolar ablation in 73%, low-ionic irrigation in 26%, bipolar ablation in 15% and ethanol ablation in 1%. Acute PVC suppression was achieved in 75% of patients. Following the procedure, the PVC burden was reduced to 5.8±8.4%. The mean follow-up was 15±14 months and 16 patients underwent a repeat ablation. CONCLUSION: Ablation of intramural PVCs is challenging; acute arrhythmia elimination is achieved in 3/4 patients, and non-conventional approaches are often necessary for success.

Perioperative Safety and Early Patient and Device Outcomes Among Subcutaneous Versus Transvenous Implantable Cardioverter Defibrillator Implantations : A Randomized, Multicenter Trial.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) improve survival in patients at risk for cardiac arrest, but are associated with intravascular lead-related complications. The subcutaneous ICD (S-ICD), with no intravascular components, was developed to minimize lead-related complications. OBJECTIVE: To assess key ICD performance measures related to delivery of ICD therapy, including inappropriate ICD shocks (delivered in absence of life-threatening arrhythmia) and failed ICD shocks (which did not terminate ventricular arrhythmia). DESIGN: Randomized, multicenter trial. (ClinicalTrials.gov: NCT02881255). SETTING: The ATLAS trial. PATIENTS: 544 eligible patients (141 female) with a primary or secondary prevention indication for an ICD who were younger than age 60 years, had a cardiogenetic phenotype, or had prespecified risk factors for lead complications were electrocardiographically screened and 503 randomly assigned to S-ICD (251 patients) or transvenous ICD (TV-ICD) (252 patients). Mean follow-up was 2.5 years (SD, 1.1). Mean age was 49.0 years (SD, 11.5). MEASUREMENTS: The primary outcome was perioperative major lead-related complications. RESULTS: There was a statistically significant reduction in perioperative, lead-related complications, which occurred in 1 patient (0.4%) with an S-ICD and in 12 patients (4.8%) with TV-ICD (-4.4%; 95% CI, -6.9 to -1.9; P = 0.001). There was a trend for more inappropriate shocks with the S-ICD (hazard ratio [HR], 2.37; 95% CI, 0.98 to 5.77), but no increase in failed appropriate ICD shocks (HR, 0.61 (0.15 to 2.57). Patients in the S-ICD group had more ICD site pain, measured on a 10-point numeric rating scale, on the day of implant (4.2 ± 2.8 vs. 2.9 ± 2.2; P < 0.001) and 1 month later (1.3 ± 1.8 vs. 0.9 ± 1.5; P = 0.035). LIMITATION: At present, the ATLAS trial is underpowered to detect differences in clinical shock outcomes; however, extended follow-up is ongoing. CONCLUSION: The S-ICD reduces perioperative, lead-related complications without significantly compromising the effectiveness of ICD shocks, but with more early postoperative pain and a trend for more inappropriate shocks. PRIMARY FUNDING SOURCE: Boston Scientific.

Prognostic Value of Nonischemic Ringlike Left Ventricular Scar in Patients With Apparently Idiopathic Nonsustained Ventricular Arrhythmias.

BACKGROUND: Left ventricular (LV) scar on late gadolinium enhancement (LGE) cardiac magnetic resonance has been correlated with life-threatening arrhythmic events in patients with apparently idiopathic ventricular arrhythmias (VAs). We investigated the prognostic significance of a specific LV-LGE phenotype characterized by a ringlike pattern of fibrosis. METHODS: A total of 686 patients with apparently idiopathic nonsustained VA underwent contrast-enhanced cardiac magnetic resonance. A ringlike pattern of LV scar was defined as LV subepicardial/midmyocardial LGE involving at least 3 contiguous segments in the same short-axis slice. The end point of the study was time to the composite outcome of all-cause death, resuscitated cardiac arrest because of ventricular fibrillation or hemodynamically unstable ventricular tachycardia and appropriate implantable cardioverter defibrillator therapy. RESULTS: A total of 28 patients (4%) had a ringlike pattern of scar (group A), 78 (11%) had a non-ringlike pattern (group B), and 580 (85%) had normal cardiac magnetic resonance with no LGE (group C). Group A patients were younger compared with groups B and C (median age, 40 vs 52 vs 45 years; P<0.01), more frequently men (96% vs 82% vs 55%; P<0.01), with a higher prevalence of family history of sudden cardiac death or cardiomyopathy (39% vs 14% vs 6%; P<0.01) and more frequent history of unexplained syncope (18% vs 9% vs 3%; P<0.01). All patients in group A showed VA with a right bundle-branch block morphology versus 69% in group B and 21% in group C (P<0.01). Multifocal VAs were observed in 46% of group A patients compared with 26% of group B and 4% of group C (P<0.01). After a median follow-up of 61 months (range, 34-84 months), the composite outcome occurred in 14 patients (50.0%) in group A versus 15 (19.0%) in group B and 2 (0.3%) in group C (P<0.01). After multivariable adjustment, the presence of LGE with ringlike pattern remained independently associated with increased risk of the composite end point (hazard ratio, 68.98 [95% CI, 14.67-324.39], P<0.01). CONCLUSIONS: In patients with apparently idiopathic nonsustained VA, nonischemic LV scar with a ringlike pattern is associated with malignant arrhythmic events.

Is Maintenance of Sinus Rhythm of Value in Patients with Atrial Fibrillation and Heart Failure?

PURPOSE OF REVIEW: Heart failure (HF) and atrial fibrillation (AF) frequently co-exist, with the prevalence of AF increasing in patients with more advanced HF symptoms. When present, AF increases morbidity and mortality in patients with HF. The purpose of this review is to examine emerging evidence addressing the value of restoration and maintenance of sinus rhythm in patients with HF. RECENT FINDINGS: Earlier trials comparing a rhythm control strategy with antiarrhythmic drugs have failed to demonstrate benefit in patients with HF and reduced ejection fraction. More recent trials, including the recently published RAFT-AF, utilizing catheter ablation for rhythm control, have shown greater promise, possibly due to reduced medication-related side effects and higher efficacy in maintaining sinus rhythm. A strategy of sinus rhythm maintenance with catheter ablation appears to improve mortality, reduce HF events and improve quality of life in patients with AF and HF.

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.

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.

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.

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.

Cardiovascular implantable electronic device lead extraction: evidence, techniques, results, and future directions.

PURPOSE OF REVIEW: Cardiovascular implantable electronic devices are widely used to treat symptomatic arrhythmias, prevent sudden cardiac death, and improve symptoms and cardiac function. Continued population growth and expanding indications have resulted in a progressive increase in the number of cardiovascular implantable electronic device implantations. Mirroring this growth, an increasing number of leads require removal because of a variety of indications. Transvenous lead extraction continues to evolve with better techniques and risk-management strategies. This review highlights the indications, techniques, procedural outcomes, and future directions of arrhythmia device management and extraction. RECENT FINDINGS: Indications for extractions are reviewed in light of newly published data. Same day contralateral reimplantation has been shown to be safe in patients with localized pocket infection. Alternative extraction techniques, utilizing the femoral and internal jugular veins, provide additional routes for device removal as stand-alone procedures or in cases of difficult extraction via the subclavian vein. Preprocedural imaging to identify adherence sites and cardiac perforation can help to reduce complications. Routine capsulectomy at generator change does not seem to reduce the risk of device infection, and multiple trials are underway to assess other methods of reducing infections as part of a lead management strategy. SUMMARY: Improvement in technology, alternative routes of extraction and preprocedural imaging continue to add to procedural efficacy and reduce complication rates of lead extraction.

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.

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.

Effects of Age-Related Aortic Root Anatomic Changes on Left Ventricular Outflow Tract Pace-Mapping Morphologies: A Cardiac Magnetic Resonance Imaging Validation Study.

INTRODUCTION: Outflow tract ventricular arrhythmias (OT VAs) are common and catheter ablation is an effective treatment option. We sought to investigate the relationship between age-related anatomic aortic root changes and QRS morphology during left ventricular outflow tract (LVOT) pace-mapping using cardiac magnetic resonance (CMR) imaging. METHODS AND RESULTS: Fifty-one patients undergoing CMR imaging were divided into 3 groups based on age (<40, 40-60, >60 years). We measured the angle of the aortic root, the aorta to ventricular septal angle, the distance between the right coronary cusp (RCC) and left coronary cusp (LCC), and the distance between the ascending and descending aorta. Additionally, we evaluated the QRS morphologies obtained during pace-mapping from the LVOT. In older patients, LCC was more superior to the RCC (P < 0.01). Age was positively correlated with the aortic root angle (r2 = 0.481, P < 0.01) as well as the distances between the ascending and descending aorta at a level below the arch (r2 = 0.569, P < 0.01). In older patients, LVOT pace-mapping (performed in 16 patients) demonstrated higher maximal R-wave amplitude, and was greater when pacing from the LCC versus the RCC in lead III (1.8 ± 0.7 vs. 1.0 ± 0.5 mV, P = 0.02). CONCLUSION: The anatomy of the aortic root changes with age, and age-related aortic root changes may affect the QRS morphology during pace-mapping. Understanding the potential anatomic changes that accompany aging is important to maximize the efficacy of catheter ablation of OT VAs.