Electrical storm after left ventricular assist device (LVAD) implantation.

INTRODUCTION: Ventricular tachycardia storm or electrical storm (ES) is a common complication following left ventricular assist device (LVAD) implantation. The factors contributing to ES and outcomes are less studied. The study aimed to determine the factors associated with ES and the probability of survival in patients undergoing LVAD in three tertiary centers over a span of 15 years. METHODS: We performed a retrospective cohort study on all patients who underwent LVAD implantation at the Mayo Clinic (Rochester, Phoenix, and Jacksonville) from January 1, 2006 to December 31, 2020. ES was defined as ≥3 episodes of sustained ventricular tachycardia over a period of 24 h with no identifiable reversible cause. Detailed chart reviews of the electronic health records within the Mayo Clinic and outside medical records were performed. RESULTS: A total of 883 patients who underwent LVAD implantation were included in our study. ES occurred in 7% (n = 61) of patients with a median of 13 days (interquartile range [IQR]: 5-297 days) following surgery. We found 57% of patients (n = 35) developed ES within 30 days, while 43% (n = 26) patients developed ES at a median of 545  (IQR 152-1032) days after surgery. Following ES, 26% of patients died within 1 year. Patients with ES had a significant association with a history of ventricular arrhythmias and implantable cardioverter defibrillator (ICD) shocks before the procedure. ES was significantly associated with reduced survival compared to patients without ES (hazards ratio [HR]: 1.92, 95% CI: 1.39-2.64, p < .001). CONCLUSION: Following LVAD implantation, the rate of ES was 7% with majority of ES occurring within 30 days of LVAD. Risk factors for ES included pre-implant history of ventricular arrhythmias and ICD shock. ES was significantly associated with reduced survival compared to patients without ES.

Ventricular arrhythmias in patients with prior aortic valve intervention: Characteristics, ablation and outcomes.

INTRODUCTION: Data regarding ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation in patients with aortic valve (AV) intervention (AVI) is limited. Catheter ablation (CA) can be challenging given perivalvular substrate in the setting of prosthetic valves. We sought to investigate the characteristics, safety, and outcomes of CA in patients with prior AVI and ventricular arrhythmias (VA). METHODS: We identified consecutive patients with prior AVI (replacement or repair) who underwent CA for VT or PVC between 2013 and 2018. We investigated the mechanism of arrhythmia, ablation approach, perioperative complications, and outcomes. RESULTS: We included 34 patients (88% men, mean age 64 ± 10.4 years, left ventricular (LV) ejection fraction 35.2 ± 15.0%) with prior AVI who underwent CA (22 VT; 12 PVC). LV access was obtained through trans-septal approach in all patients except one patient who had percutaneous transapical access. One patient had combined retrograde aortic and trans-septal approach. Scar-related reentry was the dominant mechanism of induced VTs. Two patients had bundle branch reentry VTs. In the VT group, substrate mapping demonstrated heterogeneous scar that involved the peri-AV area in 95%. Despite that, the site of successful ablation included the periaortic region only in 6 (27%) patients. In the PVC group, signal abnormalities consistent with scar in the periaortic area were noted in 4 (33%) patients. In 8 (67%) patients, the successful site of ablation was unrelated to the periaortic area. No procedure-related complications occurred. The survival and recurrence-free survival rate at 1 year tended to be lower in VT group than in PVC group (p = .06 and p = .05, respectively) with a 1-year recurrence-free survival rate of 52.8% and 91.7%, respectively. No arrhythmia-related death was documented on long-term follow-up. CONCLUSION: CA of VAs can be performed safely and effectively in patients with prior AVI.

Catheter ablation of atrial fibrillation in patients with and without hypertrophic cardiomyopathy: systematic review and meta-analysis.

BACKGROUND: Atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM). There is limited data regarding the outcomes of AF catheter ablation in HCM patients. In this study, we aimed to synthesize all available evidence on the effectiveness of ablation of AF in patients with HCM compared to those without HCM. METHODS AND RESULTS: We systematically reviewed bibliographic databases to identify studies published through February 2023. We included cohort studies with available quantitative information on rates of recurrent atrial arrhythmias, anti-arrhythmic drug (AAD) therapy, and repeat ablation procedures after initial AF ablation in patients with vs without HCM. Estimates were combined using random-effects meta-analysis models and reported as risk ratios (RR) and 95% confidence intervals (CI). Eight studies were included in quantitative synthesis (262 HCM and 642 non-HCM patients). During median follow-up 13-54 months across studies, AF recurrence rates ranged from 13.3% to 92.9% in HCM and 7.6% to 58.8% in non-HCM patients. The pooled RR for recurrent atrial arrhythmia after the first AF ablation in HCM patients compared to non-HCM controls was 1.498 (95% CI = 1.305-1.720; P < 0.001). During follow-up, HCM patients more often required AAD therapy (RR = 2.844; 95% CI = 1.713-4.856; P < 0.001) and repeat AF ablation (RR = 1.544; 95% CI = 1.070-2.228; P = 0.02). The pooled RR for recurrent atrial arrhythmias after the last AF ablation was higher in patients with HCM than those without HCM (RR = 1.607; 95% CI = 1.235-2.090; P < 0.001). CONCLUSIONS: Compared to non-HCM patients, those with HCM had higher rates of recurrent atrial arrhythmias, AAD use, and need for repeat AF ablation after initial ablation of AF.

One-year outcomes of catheter ablation for atrial fibrillation in young patients.

BACKGROUND: Atrial fibrillation (AF) is relatively less frequent in younger patients (age < 50). Recently, studies have suggested that early restoration of sinus rhythm may lead to improved outcomes compared with rate control, however the efficacy of catheter ablation for AF in young is scarce. METHODS: We included all hospitalized patients between 18 and 50 years with a diagnosis of AF from the Nationwide Readmission Database 2016-2017 from the Healthcare Cost and Utilization Project. Demographic and comorbidity data were collected and analyzed. Outcomes assessed included one-year AF readmission rates, all-cause readmission, ischemic stroke, and all-cause mortality. Subgroup analyses were performed for all demographic and comorbidity variables. RESULTS: Overall, 52,598 patients (medium age 44, interquartile range 38-48, female 25.7%) were included in the study, including 2,146 (4.0%) who underwent catheter ablation for AF. Patients who underwent catheter ablation had a significantly lower rate of readmission for AF or any cause at one year (adjusted hazard ratios (HR) of 0.52 [95% confidence interval (CI): 0.43-0.63] and HR of 0.81 [95% CI: 0.72-0.89], respectively). There was no difference in 1-year readmission for stroke or all-cause mortality between the two groups. Subgroup analyses showed a consistent reduction in the risk of AF readmission among major demographic and comorbidity subgroups. CONCLUSION: Catheter ablation in young patients with AF was associated with a reduction in 1-year AF related and all-cause readmissions. These data merit further prospective investigation for validation, through dedicated registries and multicenter collaborations to include young AF from diverse population.

Vein of Marshall alcohol ablation for dormant pulmonary vein conduction: A case report.

We report a case of alcohol ablation into a vein of Marshall for recurrent dormant conduction into the pulmonary veins with adenosine testing in a patient where two prior ablation attempts failed to isolate the left vein.

Characteristics and outcomes of ventricular tachycardia and premature ventricular contractions ablation in patients with prior mitral valve surgery.

BACKGROUND: Data regarding ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation following mitral valve surgery (MVS) is limited. Catheter ablation (CA) can be challenging given perivalvular substrate in the setting of mitral annuloplasty or prosthetic valves. OBJECTIVE: To investigate the characteristics, safety, and outcomes of radiofrequency CA in patients with prior MVS and ventricular arrhythmias (VA). METHODS: We identified consecutive patients with prior MVS who underwent CA for VT or PVC between January 2013 and December 2018. We investigated the mechanism of arrhythmia, ablation approach, peri-operative complications, and outcomes. RESULTS: In our cohort, 31 patients (77% men, mean age 62.3 ± 10.8 years, left ventricular ejection fraction 39.2 ± 13.9%) with prior MVS underwent CA (16 VT; 15 PVC). Access to the left ventricle was via transseptal approach in 17 patients, and a retrograde aortic approach was used in 13 patients. A combined transseptal and retrograde aortic approach was used in one patient, and a percutaneous epicardial approach was combined with trans-septal approach in one patient. Heterogenous scar regions were present in 94% of VT patients and scar-related reentry was the dominant mechanism of VT. Forty-seven percent of PVC patients had abnormal substrate at the site targeted for ablation. Clinical VA substrates involved the peri-mitral area in six patients with VT and five patients with PVC ablation. No procedure-related complications were reported. The overall recurrence-free rate at 1-year was 72.2%; 67% in the VT group and 78% in the PVC group. No arrhythmia-related death was documented on long-term follow-up. CONCLUSION: CA of VAs can be performed safely and effectively in patients with MVS.

Leak closure following left atrial appendage exclusion procedures: A multicenter registry.

BACKGROUND: Though infrequent, incomplete left atrial appendage closure (LAAC) may result from residual leaks. Percutaneous closure has been described though data is limited. METHODS: We compiled a registry from four centers of patients undergoing percutaneous closure of residual leaks following LAAC via surgical means or with the Watchman device. Leak severity was classified as none (no leak), mild (1-2 mm), moderate (3-4 mm), or severe (≥5 mm). Procedural and clinical success was defined as the elimination of leak or mild residual leak at the conclusion of the procedure or follow-up, respectively. RESULTS: Of 72 (age 72.2 ± 9.2 years; 67% male) patients, 53 had undergone prior LAAC using the Watchman device and 19 patients surgical LAAC. Mean CHADS2 -VA2 Sc score was 4.0 ± 1.8. The median leak size was 5 mm, range: 2-13). A total of 13 received Amplatzer Vascular Plug-II, 18 received Amplatzer Duct Occluder-II and 40 patients received coils. One underwent closure using a 21 mm-Watchman. Procedural success was 94%. Zero surgical and nine Watchman patients (13%) had a residual leak at procedural-end (five mild, three moderate, and one severe)-only one patient had no reduction in leak size. Overall leak size reduction was 94%. Two (3%) had intraoperative pericardial effusion. There were no device embolizations, device-related thrombi, or procedural deaths. Clinical success was maintained at 94%. Two had cerebrovascular accidents-at 2 days (transient ischemic attack) and 10 months postprocedure. Two had major bleeding outside the 30-day periprocedural window. CONCLUSION: Percutaneous closure of residual leaks following left atrial appendage closure is feasible and associated with good outcomes. The procedural risk appears to be satisfactory.

Cardiac ablation with pulsed electric fields: principles and biophysics.

Pulsed electric fields (PEFs) have emerged as an ideal cardiac ablation modality. At present numerous clinical trials in humans are exploring PEF as an ablation strategy for both atrial and ventricular arrhythmias, with early data showing significant promise. As this is a relatively new technology there is limited understanding of its principles and biophysics. Importantly, PEF biophysics and principles are starkly different to current energy modalities (radiofrequency and cryoballoon). Given the relatively novel nature of PEFs, this review aims to provide an understanding of the principles and biophysics of PEF ablation. The goal is to enhance academic research and ultimately enable optimization of ablation parameters to maximize procedure success and minimize risk.

Catheter ablation of ventricular tachycardia in patients with postinfarction left ventricular aneurysm.

BACKGROUND: While ventricular tachycardia (VT) in the setting of postmyocardial infarction left ventricular aneurysms (LVA) is not uncommonly encountered, there is a scarcity of data regarding the safety, efficacy, and outcomes of ablation of VT in this subset of patients. METHODS: Our study included consecutive patients aged 18 years or older with postmyocardial infarction LVA who presented to Mayo Clinic for catheter ablation of VT between 2002 and 2018. RESULTS: Of 34 patients, the mean age was 70.4 ± 9.1 years; 91% were male. Mean LVEF was 29 ± 9.7% and left ventricular end-diastolic dimension was 64.9 ± 6.6 mm. The site of the LVA was apical in 21 patients (62%). Fifteen patients (44%) presented with electrical storm or incessant VT. Nine patients (26%) had a history of intracardiac thrombus. All except for one patient had at least one VT originating from the aneurysm. The mean number of VTs was 2.9 ± 1.7. All patients underwent ablation at the site of the aneurysm. Ablation outside the aneurysm was performed in 13 patients (38%). Low-voltage fractionated potentials and/or late potentials at the aneurysmal site were present in all cases. Complete elimination of all VTs was achieved in 18 (53%), while the elimination of the clinical VT with continued inducibility of nonclinical VTs was achieved in a further 11 patients (32%). Two patients developed cardiac tamponade requiring pericardiocentesis. During a mean follow-up period of 2.3 ± 2.4 years, 11 patients (32%) experienced VT recurrence. Freedom from all-cause mortality at 1-year follow-up was 94%. CONCLUSION: Radiofrequency catheter ablation targeting the aneurysmal site is a feasible and reasonably effective management strategy for clinical VTs in patients with postinfarction LVA.

Catheter ablation of premature ventricular contractions originating from periprosthetic aortic valve regions.

BACKGROUND: Little is known about the ablation outcomes of premature ventricular contractions (PVCs) that originate from the periprosthetic aortic valve (PPAV) regions of patients with aortic valve replacement (AVR). METHODS AND RESULTS: Our study had 11 patients who underwent catheter ablation for PVCs arising from the PPAV regions (bioprosthetic aortic valve, n = 5; mechanical aortic valve, n = 6). The PVC characteristics, procedure characteristics, and efficacy of ablation were compared with the control group (n = 33). At baseline, the PPAV group had a lower left ventricular ejection fraction (mean [SD], 41% [12%] vs. 51% [8%]; p = .002). The rate of acute ablation success was 90.9% in the PPAV group. Ablation sites were identified above the left coronary cusp (LCC) and right coronary cusp commissure (LRCC) in one PVC, below the prosthetic valve in eight PVCs (four below LCC and four below LRCC), and within the distal coronary sinus in two PVCs. The mean procedure time, fluoroscopy time, and radiation in the PPAV group were all significantly greater than those in the control group (all p < .05). However, the number of radiofrequency ablation energy deliveries was not different. The PPAV group had a long-term success rate compared with the control group (72.7% vs. 87.9%, p = .48) and an increase of left ventricular ejection fraction from 43% to 49% after successful PVC ablation at follow-up (p < .001). Echocardiography showed no significant change in valve regurgitation after ablation. No new atrioventricular block occurred. CONCLUSION: PVCs arising from PPAV regions can be successfully ablated in patients with prior AVR, without damaging the prosthetic aortic valve and atrioventricular conduction.

Utilization and procedural adverse outcomes associated with Watchman device implantation.

AIMS: The Food and Drug Administration (FDA) approval of the Watchman device [percutaneous left atrial appendage occlusion (LAAO)] has resulted in the widespread use of this procedure in many centres across the USA. We sought to estimate the nationwide utilization and frequency of adverse outcomes associated with Watchman device implantation. The objective of this study was to evaluate the Watchman device implantation peri-procedural complications and comparison of the results with the previous studies. METHODS AND RESULTS: The National Inpatient Sample (NIS) was queried for all hospitalizations with a primary diagnosis of atrial fibrillation or atrial flutter during the year 2016 with percutaneous LAAO during the same admission (ICD-10 code-02L73DK). The frequency of peri-procedural complications, including mortality, procedure-related stroke, major bleeding requiring blood transfusion, and pericardial effusion, was assessed. We compared the complication rates with the published randomized controlled trials and the European Watchman registry. An estimated 5175 LAAO procedures were performed in 2016. The majority of procedures was performed in males (59.1%), age ≥75 years (58.7%), and White (83.1%). The overall complication rate was 1.9%. The in-hospital mortality was 0.29%. Pericardial effusion requiring pericardiocentesis was the most frequent complication (0.68%). Bleeding requiring transfusion was noted in 0.1% of device implants. The rates of post-procedure stroke and systemic embolism were 0% and 0.29%, respectively. CONCLUSION: Percutaneous LAAO with the Watchman device in the USA is associated with low in-hospital complications and a similar safety profile to a recently published EWOLUTION cohort. The complication rates were lower than those reported in the major randomized clinical trials (RCTs). We report the frequency of peri-procedural complications of the LAAO using the Watchman device from the NIS database. We also compare the frequency of peri-procedural complications with the previously published RCTs and EWOLUTION cohort. Our findings are in concordance with findings from EWOLUTION cohort and compare favourably with RCTs.

Sinus rhythm heart rate increase after atrial fibrillation ablation is associated with lower risk of arrhythmia recurrence.

BACKGROUND: Pulmonary vein isolation (PVI) with autonomic modulation may be more successful than PVI alone for atrial fibrillation (AF) ablation and may be signaled by changes in sinus rhythm heart rate (HR) post ablation. We sought to determine if a change in sinus rhythm HR predicted AF recurrence post PVI. METHODS: Patients who underwent AF ablation from 2000 to 2011 were included if sinus rhythm was noted on ECG within 90 days pre and 7 days post ablation. Basic ECG interval and HR changes were analyzed and outcomes determined. RESULTS: A total of 1152 patients were identified (74.3% male, mean age 57 ± 11 years). Mean AF duration was 5.2 ± 5.3 years. Paroxysmal AF was noted in 712 (61.8%) of the patients. Mean EF was 61% ± 6%. Sinus rhythm HR was 61 ± 11 pre-ablation and 76 ± 13 bpm post-ablation (27% ± 24% increase, p < .001). The ability of relative HR change post-ablation to predict AF recurrence was borderline (hazard ratio 0.65 [0.41-1.01], p = .067). With patients separated into quartiles based on the relative HR change, the upper quartile with the largest relative increase in HR had a significantly lower rate of AF recurrence compared to the lowest quartile following multi variable modeling (p = .038). There were significant changes in PR (171 ± 28 to 167 ± 30 ms) and QTc (424 ± 25 to 434 ± 29 ms) intervals (both p < .001) but these were not predictive of outcome. CONCLUSION: Relative changes in HR post AF ablation correlates with AF recurrence. Further prospective studies are needed to confirm this relationship.

A novel technique-Prophylactic septal radiofrequency ablation to prevent left ventricular outflow tract obstruction with transcatheter mitral valve replacement (RADIO-TMVR).

Transcatheter mitral valve replacement (TMVR) with off-label use of aortic balloon-expandable transcatheter heart valves has emerged as a therapeutic option in high-surgical risk patients with severe mitral annular calcification. Left ventricular outflow tract (LVOT) obstruction post valve deployment is a major limitation. We describe a case of septal reduction therapy using radiofrequency ablation (RFA) when established methods of septal reduction were either ineffective or not feasible. RFA permitted successful enlargement of the LVOT area and subsequent TMVR.

Risk stratification for stroke in atrial fibrillation: a critique.

Despite the demonstrable success of oral anticoagulants in reducing the rate of stroke in patients with atrial fibrillation, they continue to be seriously underutilized. Indications for their use as stated in the guidelines incorporate a number of risk score algorithms, the most widely used being the CHA2DS2-VASc score. Nonetheless there are several limitations to the various scores currently in clinical use and a critique of these is the focus of this review. In this review we discuss the pathophysiology of atrial fibrillation and its role in thromboembolic stroke risk. We amalgamate this with the basis of major professional society anticoagulation recommendations with regards to the strengths and limitations of current risk stratification strategies and discuss gaps in our current evidence base and next steps to address those gaps.

Mortality and Cerebrovascular Events After Heart Rhythm Disorder Management Procedures.

BACKGROUND: Recognition of rates and causes of hard, patient-centered outcomes of death and cerebrovascular events (CVEs) after heart rhythm disorder management (HRDM) procedures is an essential step for the development of quality improvement programs in electrophysiology laboratories. Our primary aim was to assess and characterize death and CVEs (stroke or transient ischemic attack) after HRDM procedures over a 17-year period. METHODS: We performed a retrospective cohort study of all patients undergoing HRDM procedures between January 2000 and November 2016 at the Mayo Clinic. Patients from all 3 tertiary academic centers (Rochester, Phoenix, and Jacksonville) were included in the study. All in-hospital deaths and CVEs after HRDM procedures were identified and were further characterized as directly or indirectly related to the HRDM procedure. Subgroup analysis of death and CVE rates was performed for ablation, device implantation, electrophysiology study, lead extraction, and defibrillation threshold testing procedures. RESULTS: A total of 48 913 patients (age, 65.7±6.6 years; 64% male) who underwent a total of 62 065 HRDM procedures were included in the study. The overall mortality and CVE rates in the cohort were 0.36% (95% confidence interval [CI], 0.31-0.42) and 0.12% (95% CI, 0.09-0.16), respectively. Patients undergoing lead extraction had the highest overall mortality rate at 1.9% (95% CI, 1.34-2.61) and CVE rate at 0.62% (95% CI, 0.32-1.07). Among patients undergoing HRDM procedures, 48% of deaths directly related to the HDRM procedure were among patients undergoing device implantation procedures. Overall, cardiac tamponade was the most frequent direct cause of death (40%), and infection was the most common indirect cause of death (29%). The overall 30-day mortality rate was 0.76%, with the highest being in lead extraction procedures (3.08%), followed by device implantation procedures (0.94%). CONCLUSIONS: Half of the deaths directly related to an HRDM procedure were among the patients undergoing device implantation procedures, with cardiac tamponade being the most common cause of death. This highlights the importance of the development of protocols for the quick identification and management of cardiac tamponade even in procedures typically believed to be lower risk such as device implantation.

Silent and non-silent thromboembolic events after ventricular tachycardia ablation: Modifiable risk with postprocedure anticoagulation?

There is increasing recognition of silent and clinically apparent thromboembolic events after left-sided ventricular tachycardia (VT) ablation. However, unlike atrial fibrillation ablation procedures where postablation oral anticoagulation (OAC) is universal, there is significant practice variation in OAC use after VT ablation. Herein, we review the data on post-VT ablation thromboembolism and evidence on the use of OAC, we suggest that OAC merits consideration in most cases after a balanced assessment of risks and benefits in individual patients, and we discuss future directions.

Sudden cardiac arrest and ventricular arrhythmias following first type I myocardial infarction in the contemporary era.

INTRODUCTION: Myocardial infarction (MI) is associated with an increase in subsequent heart failure (HF), recurrent ischemic events, sudden cardiac arrest, and ventricular arrhythmias (SCA-VA). The primary objective of the study to determine the role of intercurrent HF and ischemic events on the development of SCA-VA following first type I MI. METHODS AND RESULTS: A retrospective cohort study of patients experiencing first type 1 MI in Olmsted County, Minnesota (2002-2012) was conducted by identifying patients using the medical records linkage system (Rochester epidemiology project). Patients aged ≥18 years were followed from the time of MI till death or 31 July, 2017. Intercurrent HF and ischemic events were the primary exposures following MI and their association with outcome SCA-VA was assessed. Eight hundred and sixty-seven patients (mean age was 63 ± 14.5 years; 69% male; 49.8% ST-elevation myocardial infarction) who had their first type I MI during the study period were included. Majority of acute MI patients were revascularized using percutaneous coronary intervention and bypass surgery (628 [72.43%] and 87 [10.03%] respectively). During a mean follow-up of 7.69 ± 4.17 years, HF, recurrent ischemic events and SCA-VA occurred in 155 (17.9%), 245 (28.3%), and 40 (4.61%) patients respectively. Low ejection fraction (adjusted hazard ratio [HR] 0.95; 95% confidence interval [CI], 0.93-0.98; P < .001), intercurrent HF (adjusted HR 3.11; 95% CI, 1.39-6.95; P = .006) and recurrent ischemic events (adjusted HR 3.47; 95% CI, 1.68-7.18; P < .001) were associated with subsequent SCA-VA. CONCLUSION: SCA-VA occurred in a small proportion of patients after MI and is associated with intercurrent HF and recurrent ischemic events.

Comparing the incidence of ventricular arrhythmias during epicardial ablation in swine versus canine models.

BACKGROUND: Choosing the appropriate animal model for development of novel technologies requires an understanding of anatomy and physiology of these different models. There are little data about the characteristics of different animal models for the study of technologies used for epicardial ablation. We aimed to compare the incidence of ventricular arrhythmias during epicardial radiofrequency ablation between swine and canine models using novel epicardial ablation catheters. METHODS: We conducted a retrospective study using data obtained from epicardial ablation experiments performed on swine (Sus Scrofa) and canine (Canis familiaris) models. We compared the incidence of ventricular arrhythmias during ablation between swine and canine using multivariate regression analysis. Six swine and six canine animals underwent successful epicardial radiofrequency ablation. A total of 103 ablation applications were recorded. RESULTS: Ventricular arrhythmias requiring cardioversion occurred in 13.11% of radiofrequency ablation applications in swine and 9.75% in canine (relative risk: 117.6%, 95% confidence interval [CI]: 83.97-164.69, animal-based odds ratio [OR]: .55, 95% CI: .23-61.33; P = .184). When adjusting for application position, duration of ablation and power, the odds of developing potentially lethal ventricular arrhythmia in swine increased significantly compared to canine (OR: 3.60, 95% CI: 1.35-9.55; P = .010). CONCLUSIONS: The swine myocardium is more susceptible to developing ventricular arrhythmias compared to canine model during epicardial ablation. This issue should be carefully considered in future studies.

Percutaneous epicardial pacing using a novel transverse sinus device.

BACKGROUND: Transvenous lead implantation has multiple drawbacks and complications that can be overcome by epicardial lead placement. We aimed to design percutaneously implanted epicardial leads that are anchored through the transverse sinus (TS). METHODS AND RESULTS: We designed a novel multielectrode pacing device with four bipole electrode pairs. The device is advanced through the TS, with both ends externalized out of the pericardium. We tested the prototype in one proof-of-concept and 5 additional acute canine experiments. The TS device recorded ventricular and atrial electrograms. The median amplitude of near-field ventricular electrograms was 3.3 mA (IQR 2.0-4.3) and of near-field atrial electrograms was 2.1 mA (IQR 1.3-2.2). The median ventricular threshold (N  =  30) was 1.1 mA (IQR 0.7-3.1) at a median pulse width of 0.5 ms (IQR 0.5-0.5). The median atrial threshold (N  =  10) was 2.4 mA (IQR 1.1-7.8) at a median pulse width of 0.5 ms (IQR 0.5-0.9). Right and left ventricular and atrial pacing morphologies were noted while pacing electrodes adjacent to these chambers. Simultaneous left (LV) and right ventricular (RV) pacing showed reduction in QRS duration from 116 ms (RV) and 105 ms (LV) to 91 ms. On necropsy, the device was located in the TS in all animals. There were TS abrasions in one animal, and no other acute complications. CONCLUSIONS: This study highlights a novel approach to epicardial pacing harnessing the unique anatomy of the transverse sinus as an anchoring point. Placement of this novel transverse sinus device was safe and feasible, with acceptable atrial and ventricular thresholds.

Impact of sedation vs. general anaesthesia on percutaneous epicardial access safety and procedural outcomes.

Aims: Patient movement while under moderate/deep sedation may complicate percutaneous epicardial access (EpiAcc), mapping and ablation. We sought to compare procedural outcomes in patients undergoing EpiAcc under sedation vs. general anaesthesia (GA) for ablation. Methods and results: Patients undergoing EpiAcc between January 2004 and July 2014 were included. Safety, procedural, and clinical outcomes were compared between patients undergoing EpiAcc under sedation or GA for ventricular tachycardia or premature ventricular complex ablation. Between January 2004 and July 2014, 170 patients underwent EpiAcc (mean age, 53.2 ± 15.8 years; average ejection fraction, 44.3 ± 15.3%). The majority (122 [72%] patients) were male. GA was used in 69 (40.6%). There was no difference in route of access (more often anterior, 53.0%) or the rate of successful access (96% overall) between groups. Similarly, the site of ablation (endocardial vs. epicardial vs. combined endocardial/epicardial) was similar between groups. Complications were equally seen between groups-the most frequent event/complication was pericardial effusion, occurring in 10.6% of patients. Finally, procedural and clinical success rates between GA and sedation groups were comparable (93 vs. 91% and 44 vs. 51%, respectively, P > 0.05). Conclusions: Choice of anaesthesia for EpiAcc does not appear to significantly affect safety and procedural or clinical outcomes. For patients in whom anaesthesia may pose increased risk, it is reasonable to obtain epicardial access under sedation.