Safe and effective delivery of high-power, short-duration radiofrequency ablation lesions with a flexible-tip ablation catheter.

Background: High-power, short-duration (HPSD) radiofrequency ablation (RFA) may reduce ablation time. Concerns that catheter-mounted thermocouples (TCs) can underestimate tissue temperature, resulting in elevated risk of steam pop formation, potentially limit widespread adoption of HPSD ablation. Objective: The purpose of this study was to compare the safety and efficacy of HPSD and low-power, long-duration (LPLD) RFA in the context of pulmonary vein isolation (PVI). Methods: An open-irrigated ablation catheter with a contact force sensor and a flexible-tip electrode containing a TC at its distal end (TactiFlexTM Ablation Catheter, Sensor EnabledTM, Abbott) was used to isolate the left pulmonary veins (PVs) in 12 canines with HPSD RFA (50 W for 10 seconds) and LPLD RFA (30 W for a maximum of 60 seconds). PVI was assessed at 30 minutes and 28 ± 3 days postablation. Computed tomographic scans were performed to assess PV stenosis after RFA. Lesions were evaluated with histopathology. Results: A total of 545 ablations were delivered: 252 with LPLD (0 steam pops) and 293 with HPSD RFA (2 steam pops) (P = .501). Ablation time required to achieve PVI was >3-fold shorter for HPSD than for LPLD RFA (P = .001). All 24 PVs were isolated 30 minutes after ablation, with 12/12 LPLD-ablated and 11/12 HPSD-ablated PVs still isolated at follow-up. Histopathology revealed transmural ablations for HPSD and LPLD RFA. No major adverse events occurred. Conclusion: An investigational ablation catheter effectively delivered RFA lesions. Ablation time required to achieve PVI with HPSD with this catheter was >3-fold shorter than with LPLD RFA.

Emerging role of artificial intelligence in cardiac electrophysiology.

Artificial intelligence (AI) and machine learning (ML) have significantly impacted the field of cardiovascular medicine, especially cardiac electrophysiology (EP), on multiple fronts. The goal of this review is to familiarize readers with the field of AI and ML and their emerging role in EP. The current review is divided into 3 sections. In the first section, we discuss the definitions and basics of AI, ML, and big data. In the second section, we discuss their application to EP in the context of detection, prediction, and management of arrhythmias. Finally, we discuss the regulatory issues, challenges, and future directions of AI in EP.

Is paroxysmal supraventricular tachycardia truly benign? Insightful association between PSVT and stroke from a National Inpatient Database Study.

BACKGROUND: Atrial fibrillation and flutter are well-known causes of stroke. Whether other atrial arrhythmias categorized as paroxysmal supraventricular tachycardia (PSVT) are associated with stroke is less clear. We aimed to evaluate the association of PSVT with ischemic and embolic stroke and its impact on short-term outcomes in hospitalized stroke patients. METHODS: National Inpatient Sample database of the USA was used to assess the association of PSVT with ischemic stroke. Atrial fibrillation and flutter were excluded to minimize the confounding effects. The association of PSVT with stroke was evaluated using univariate and multivariate analysis. Subgroup analyses by gender, age, and stroke type were also performed. RESULTS: PSVT was associated with increased odds of overall ischemic stroke in univariate [OR 1.18 (95% CI 1.09-1.27) p < 0.001] analysis. No such association was observed in multivariate analysis (OR 1.06 (95% CI 0.98-1.14) p = 0.1) or with subgroup analysis by gender and age. However, PSVT was associated with embolic stroke in both univariate (OR 2.01 (95%CI 1.67-2.43, p < 0.001) and multivariate analysis (OR 1.7 (95%CI 1.4-2.14) p < 0.001) as well as in subgroup analyses by gender and age. Furthermore, the presence of PSVT was associated with increased mortality in embolic stroke (OR 4.11, CI 2.29 to 7.39, p < 0.001) and increased total hospital cost and length of hospital stay in all stroke types. CONCLUSIONS: PSVT is independently associated with higher prevalence of embolic stroke but not with overall ischemic stroke. Patients with embolic stroke in the presence of PSVT have worse in-hospital outcomes with increased mortality.

Economic impact of contact force sensing in catheter ablation for atrial fibrillation.

AIMS: The TactiCath Contact Force Ablation Catheter Study for Atrial Fibrillation (TOCCASTAR) clinical trial compared clinical outcomes using a contact force (CF) sensing ablation catheter (TactiCath) with a catheter that lacked CF measurement. This analysis links recorded events in the TOCCASTAR study and a large claims database, IBM MarketScan®, to determine the economic impact of using CF sensing during atrial fibrillation (AF) ablation. METHODS AND RESULTS: Clinical events including repeat ablation, use of antiarrhythmic drugs, hospitalization, perforation, pericarditis, pneumothorax, pulmonary edema, pulmonary vein stenosis, tamponade, and vascular access complications were adjudicated in the year after ablation. CF was characterized as optimal if greater than or equal to 90% lesion was performed with greater than or equal to 10 g of CF. A probabilistic 1:1 linkage was created for subjects in MarketScan® with the same events in the year after ablation, and the cost was evaluated over 10 000 iterations. Of the 279 subjects in TOCCASTAR, 145 were ablated using CF (57% with optimal CF), and 134 were ablated without CF. In the MarketScan® cohort, 9811 subjects who underwent AF ablation were used to determine events and costs. For subjects ablated with optimal CF, total cost was $19 271 ± 3705 in the year after ablation. For ablation lacking CF measurement, cost was $22 673 ± 3079 (difference of $3402, P < .001). In 73% of simulations, optimal CF was associated with lower cost in the year after ablation. CONCLUSION: Compared to ablation without CF, there was a decrease in healthcare cost of $3402 per subject in the first year after the procedure when optimal CF was used.

Temporal relationships between esophageal injury type and progression in patients undergoing atrial fibrillation catheter ablation.

BACKGROUND: Currently, little is known about the onset, natural progression, and management of esophageal injuries after atrial fibrillation (AF) ablation. OBJECTIVES: We sought to provide a systematic review on esophageal injury after AF ablation and identify temporal relationships between various types of esophageal lesions, their progression, and clinical outcomes. METHODS: A comprehensive search of PubMed and Web of Science was conducted until September 21, 2017. All AF ablation patients who underwent upper gastrointestinal endoscopy within 1 week of the procedure were included. Patients with esophageal lesions were classified into 3 types by using our novel Kansas City classification: type 1: erythema; type 2a: superficial ulcers; type 2b: deep ulcers; type 3a: perforation without communication with the atria; and type 3b: perforation with atrioesophageal fistula. RESULTS: Thirty studies met our inclusion criteria. Of the 4473 patients, 3921 underwent upper gastrointestinal evaluation. The overall incidence of esophageal injuries was 15% (570). There were 206 type 1 lesions (36%), 222 type 2a lesions (39%), and 142 type 2b lesions (25%). Six of 142 type 2b lesions (4.2%) progressed further to type 3, of which, 5 were type 3a and 1 was type 3b. All type 1 and type 2a and most type 2b lesions resolved with conservative management. One type 3a and 1 type 3b lesions were fatal. CONCLUSION: Based on our classification, all type 1 and most type 2 lesions resolved with conservative management. A small percentage (4.2% [6 of 142]) of type 2b lesions progressed to perforation and/or fistula formation, and these patients need to be followed closely.

Stroke and Cardiovascular Events After Ablation or Antiarrhythmic Drugs for Treatment of Patients With Atrial Fibrillation.

Catheter ablation and antiarrhythmic drugs (AADs) are the most common rhythm-control strategies for atrial fibrillation (AF). Data comparing the rate of stroke and cardiovascular events between the treatment strategies are limited. Therefore, this observational study uses claims data to compare rate of cardiovascular hospitalization and stroke for patients with AF treated with ablation or AADs. Patients in the MarketScan dataset with AF between January 2010 and December 2014 were categorized in the ablation group if an atrial catheter ablation was performed, or in the AAD group if a relevant AAD was prescribed for AF but no ablation was performed. One year of history was required, and the index event was selected as the most recent ablation or AAD prescription closest to January 1, 2013. A 2:1 propensity score match was performed for age, gender, co-morbidities, and total medical cost in the year before index event. Outcomes included thromboembolic event (ischemic stroke, transient ischemic attack, or systemic embolism) and all cardiovascular hospitalizations. Of the 164,639 patients in the AAD group, 29,456 were matched to the 14,728 ablation patients. There were no significant differences in age (64 ± 10 in both groups), gender (58% male), or CHA2DS2-VASc score (3.2 ± 1.3). Risk of hospitalization with primary diagnosis of thromboembolic event was 41% greater in the AADs group (p < 0.001), and cardiovascular hospitalizations were 13% more likely (p < 0.001). In conclusion, patients treated with catheter ablation of AF have lower risk of thromboembolic events and cardiovascular hospitalizations than a matched cohort of patients managed with AADs.

Impact of ventricular tachycardia ablation on health care utilization.

BACKGROUND: Catheter ablation of ventricular tachycardia (VT) has been shown to reduce the number of recurrent shocks in patients with an implantable cardioverter-defibrillator (ICD). However, how VT ablation affects postprocedural medical and pharmaceutical usage remains unclear. OBJECTIVE: The purpose of this study was to investigate changes in health care resource utilization (HCRU) after VT ablation. METHODS: This large-scale, real-world, retrospective study used the MarketScan databases to identify patients in the United States with an ICD or cardiac resynchronization therapy-defibrillator (CRT-D) undergoing VT ablation. We calculated cumulative medical and pharmaceutical expenditures, office visits, hospitalizations, and emergency room (ER) visits in the 1-year periods before and after ablation. RESULTS: A total of 523 patients met the study inclusion criteria. After VT ablation, median annual cardiac rhythm-related medical expenditures decreased by $5,408. Moreover, the percentage of patients with at least 1 cardiac rhythm-related hospitalization and ER visit decreased from 53% and 41% before ablation to 28% and 26% after ablation, respectively. Similar changes were observed in the number of all-cause hospitalizations and ER visits, but there were no significant changes in all-cause medical expenditures. During the year before VT ablation, there was an increasing rate of health care resource utilization, followed by drastic slowing after ablation. CONCLUSION: This retrospective study demonstrated that catheter ablation seems to reduce hospitalization and overall health care utilization in VT patients with an ICD or CRT-D in place.

Novel automated point collection software facilitates rapid, high-density electroanatomical mapping with multiple catheter types.

INTRODUCTION: Manual, point-by-point electroanatomical mapping requires the operator to directly evaluate each point during map construction. Consequently, point collection can be a slow process. An automated 3D mapping system was developed with the goal of improving key mapping metrics, including map completion time and point density. METHODS: Automated 3D mapping software that includes morphology and cycle length discrimination functions for surface and intracardiac electrograms was developed. In five swine, electroanatomical maps (EAMs) of all four cardiac chambers were generated in sinus rhythm. Four catheters were used: two different four-pole ablation catheters, a 20-pole circular catheter, and a 64-pole basket catheter. Automated and manual 3D mapping were compared for 12 different catheter-chamber combinations (paired sets of 10 maps for most combinations, for a total of 156 maps). RESULTS: Automated 3D mapping produced more than twofold increase in the number of points per map, as compared with manual 3D mapping (P ≤0.007 for all catheter-chamber combinations tested). Automated 3D mapping also reduced map completion time by an average of 29% (P < 0.05 for all comparisons). The amount of manual editing of the maps acquired with automated 3D mapping was minimal. CONCLUSION: Automated 3D mapping with the open-platform mapping software described in this study is significantly faster than manual, point-by-point 3D mapping. This resulted in shorter mapping time and higher point density. The morphology discrimination functions effectively excluded ectopic beats during mapping in sinus rhythm and allowed for rapid mapping of intermittent ventricular ectopic beats.

Safety of catheter ablation of atrial fibrillation using fiber optic-based contact force sensing.

BACKGROUND: While the body of evidence showing the benefit of contact force (CF)-sensing catheters in improving atrial fibrillation ablation success rate is growing, real-world safety data of this technology are limited. OBJECTIVE: The aim of this study was to report the complication rate in patients undergoing ablation using a specific CF-sensing catheter (TactiCath Quartz CF ablation catheter, Abbott, St. Paul, MN) in a large worldwide database. METHODS: User-reported adverse event data from January 1, 2014 to December 31, 2015 were reviewed for the ablation catheter. These adverse events included cardiac perforation, cerebrovascular accident, atrioesophageal (AE) fistula, steam pop, and death. Rates of these adverse events, including geographic and temporal relationships, were calculated. RESULTS: Adverse events were reported in 178 of 41,709 patients (adverse event rate 0.427%). Adverse events included 117 cardiac perforations (0.281%), 5 cerebrovascular accidents (0.012%), 10 AE fistulas (0.024%), 53 audible steam pops (0.127%), and 13 deaths (0.031%). The total event rate in European countries was 0.53% vs 0.38% in the United States (P = .0082). The AE fistula event rate peaked in late 2014 and early 2015 at 0.06% and decreased over time to a steady-state 0.01%, corresponding to the initial US release, subsequent increased use, and training on the manufacturer recommended settings. CONCLUSION: Complication rates while using the TactiCath CF ablation catheter appear to decrease with training and experience. The major complication rate associated with this technology is low in the context of similar reports of conventional radiofrequency catheters.

The Impact of First Procedure Success Rate on the Economics of Atrial Fibrillation Ablation.

OBJECTIVES: The purpose of this study was to compare health care costs associated with repeat ablation of atrial fibrillation (AF) with health care costs associated with a successful first procedure. BACKGROUND: Catheter ablation has become established as a rhythm control strategy for symptomatic paroxysmal and persistent AF. The economic impact of ablation is not completely understood, and it may be affected by repeat procedures performed for recurrent AF. METHODS: The source of data was the MarketScan (Truven Health, Ann Arbor, Michigan) administrative claims dataset from April 2008 to March 2013, including U.S. patients with private and Medicare supplemental insurance. Patients who underwent an outpatient atrial ablation procedure and a diagnosis of AF were identified. Total health care cost was calculated for 1 year before and after the ablation. Patients were categorized as having undergone a repeat ablation if an additional ablation was performed in the following year. RESULTS: Of 12,027 patients included in the study, repeat ablation was performed in 2,066 (17.2%) within 1 year. Patients with repeat ablation had higher rates of emergency department visits (43.4% vs. 32.2%; < 0.001) and subsequent hospitalization (35.6% vs. 21.5%; p < 0.001), after excluding hospitalizations for the repeat procedure. Total medical cost was higher for patients with repeat ablation ($52,821 vs. $13,412; p < 0.001), and it remained 46% higher even after excluding the cost associated with additional ablations ($19,621 vs. $13,412; p < 0.001). CONCLUSIONS: Health care costs are significantly higher for patients with a repeat ablation for AF than for patients with only a single ablation procedure, even though both groups have similar baseline characteristics. The increased costs persist even after excluding the cost of the repeat ablation itself. These results emphasize the economic benefit of procedural success in AF ablation.

Scar voltage threshold determination using ex vivo magnetic resonance imaging integration in a porcine infarct model: Influence of interelectrode distances and three-dimensional spatial effects of scar.

BACKGROUND: Studies analyzing optimal voltage thresholds for scar detection with electroanatomic mapping frequently lack a gold standard for comparison. OBJECTIVE: The purpose of this study was to use a porcine infarct model with ex vivo magnetic resonance imaging (MRI) integration to characterize the relationship between interelectrode spacing and bipolar voltage thresholds and examine the influence of 3-dimensional scar on unipolar voltages. METHODS: Thirty-two combined endocardial-epicardial electroanatomic maps were created in 8 postinfarct porcine subjects (bipolar 2-mm, 5-mm, and 8-mm interelectrode spacing and unipolar) for comparison with ex vivo MRI. Two thresholds were compared: (1) 95% normal distribution and (2) best fit to MRI. Direct electrogram analysis was performed in regions across from MRI-defined scar and adjacent to scar border zone. RESULTS: A linear increase in optimal thresholds was observed with wider bipole spacing. The 95% thresholds for scar were lower than MRI-matched thresholds with moderate sensitivity for nontransmural scar (54% endo, 63% epi). Unipolar endocardial scar area exceeded MRI-defined scar, resulting in mismatched false scar in 5 of 8 (63%). Endocardial and epicardial unipolar voltages were lower than normal in regions adjacent and across from scar. CONCLUSION: Variations in interelectrode spacing necessitate tailored bipolar voltage thresholds to optimize scar detection. Statistical 95% thresholds appear to be conservative and not fully sensitive for the detection of scar defined by high-resolution ex vivo MRI. In the presence of endocardial scar, unipolar mapping to quantitatively characterize epicardial scar may be overly sensitive due to 3-dimensional spatial averaging.

Transcatheter Myocardial Needle Chemoablation During Real-Time Magnetic Resonance Imaging: A New Approach to Ablation Therapy for Rhythm Disorders.

BACKGROUND: Radiofrequency ablation for ventricular arrhythmias is limited by inability to visualize tissue destruction, by reversible conduction block resulting from edema surrounding lesions, and by insufficient lesion depth. We hypothesized that transcatheter needle injection of caustic agents doped with gadolinium contrast under real-time magnetic resonance imaging (MRI) could achieve deep, targeted, and irreversible myocardial ablation, which would be immediately visible. METHODS AND RESULTS: Under real-time MRI guidance, ethanol or acetic acid was injected into the myocardium of 8 swine using MRI-conspicuous needle catheters. Chemoablation lesions had identical geometry by in vivo and ex vivo MRI and histopathology, both immediately and after 12 (7-17) days. Ethanol caused stellate lesions with patchy areas of normal myocardium, whereas acetic acid caused homogeneous circumscribed lesions of irreversible necrosis. Ischemic cardiomyopathy was created in 10 additional swine by subselective transcoronary ethanol administration into noncontiguous territories. After 12 (8-15) days, real-time MRI-guided chemoablation-with 2 to 5 injections to create a linear lesion-successfully eliminated the isthmus and local abnormal voltage activities. CONCLUSIONS: Real-time MRI-guided chemoablation with acetic acid enabled the intended arrhythmic substrate, whether deep or superficial, to be visualized immediately and ablated irreversibly. In an animal model of ischemic cardiomyopathy, obliteration of a conductive isthmus both anatomically and functionally and abolition of local abnormal voltage activities in areas of heterogeneous scar were feasible. This represents the first report of MRI-guided myocardial chemoablation, an approach that could improve the efficacy of arrhythmic substrate ablation in the thick ventricular myocardium.

Lesion Size and Safety Comparison Between the Novel Flex Tip on the FlexAbility Ablation Catheter and the Solid Tips on the ThermoCool and ThermoCool SF Ablation Catheters.

INTRODUCTION: Next-generation catheters have been developed to reduce irrigation volume and preserve power delivery. A novel design uses a flexible tip (FlexAbility™ catheter) that directs flow to the contact surface. Because of recent safety issues with new catheters, we undertook a study in a canine heart with 3 irrigated catheters to compare efficacy and safety. METHODS: Endocardial ablation was performed by 2 independent operators in 12 anesthetized canines with the FlexAbility (St. Jude Medical), ThermoCool™ (Biosense Webster), and ThermoCool™ SF (Biosense Webster) catheters. Endocardial RF lesions were delivered with each catheter in all 4 chambers of each animal for 52 ± 16 seconds. Each chamber was randomized to receive ablation from one catheter with recording of safety events. Cardiac pathology was performed with triphenyl tetrazolium chloride stain. RESULTS: Average lesion dimensions were not significantly different between the 3 catheters. FlexAbility™ demonstrated a lower risk of steam pops relative to ThermoCool SF (P-value = 0.013) despite equal mean power and radiofrequency time. High-temperature generator shutdowns were observed with FlexAbility™ but not with either ThermoCool catheter. High-temperature shutdowns were associated with larger average impedance drops (28.5 ohms vs. 19 ohms) without compromising lesion size. CONCLUSIONS: The FlexAbility™ tip is safe and effective with no significant difference in lesion sizes compared to both standard ThermoCool and ThermoCool SF. FlexAbility™ has a significantly lower risk of steam pops compared to ThermoCool SF in a beating heart as defined predominantly by an abrupt rise of impedance.

Randomized, Controlled Trial of the Safety and Effectiveness of a Contact Force-Sensing Irrigated Catheter for Ablation of Paroxysmal Atrial Fibrillation: Results of the TactiCath Contact Force Ablation Catheter Study for Atrial Fibrillation (TOCCASTAR) Study.

BACKGROUND: Contact force (CF) is a major determinant of lesion size and transmurality and has the potential to improve efficacy of atrial fibrillation ablation. This study sought to evaluate the safety and effectiveness of a novel irrigated radiofrequency ablation catheter that measures real-time CF in the treatment of patients with paroxysmal atrial fibrillation. METHODS AND RESULTS: A total of 300 patients with symptomatic, drug-refractory, paroxysmal atrial fibrillation were enrolled in a prospective, multicenter, randomized, controlled trial and randomized to radiofrequency ablation with either a novel CF-sensing catheter or a non-CF catheter (control). The primary effectiveness end point consisted of acute electrical isolation of all pulmonary veins and freedom from recurrent symptomatic atrial arrhythmia off all antiarrhythmic drugs at 12 months. The primary safety end point included device-related serious adverse events. End points were powered to show noninferiority. All pulmonary veins were isolated in both groups. Effectiveness was achieved in 67.8% and 69.4% of subjects in the CF and control arms, respectively (absolute difference, -1.6%; lower limit of 1-sided 95% confidence interval, -10.7%; P=0.0073 for noninferiority). When the CF arm was stratified into optimal CF (≥90% ablations with ≥10 g) and nonoptimal CF groups, effectiveness was achieved in 75.9% versus 58.1%, respectively (P=0.018). The primary safety end point occurred in 1.97% and 1.40% of CF patients and control subjects, respectively (absolute difference, 0.57%; upper limit of 1-sided 95% confidence interval, 3.61%; P=0.0004 for noninferiority). CONCLUSIONS: The CF ablation catheter met the primary safety and effectiveness end points. Additionally, optimal CF was associated with improved effectiveness. CLINICAL TRIAL REGISTRATION: http://www.clinicaltrials.gov. Unique identifier: NCT01278953.

Radiofrequency Ablation to Prevent Sudden Cardiac Death.

Radiofrequency ablation may prevent or treat atrial and ventricular arrhythmias. Since some of these arrhythmias are associated with sudden cardiac death, it has been hypothesized that ablation may prevent sudden death in certain cases. We performed a literature search to better understand under which circumstances ablation may prevent sudden death and found little randomized data demonstrating the long-term effects of ablation. Current literature shows that ablation clearly prevents symptoms of arrhythmia and may reduce the incidence of sudden cardiac death in select patients, although data does not indicate improved mortality. Ongoing clinical trials are needed to better define the role of ablation in preventing sudden cardiac death.

Clinical predictors of risk for atrial fibrillation: implications for diagnosis and monitoring.

OBJECTIVE: To create a risk score using clinical factors to determine whom to screen and monitor for atrial fibrillation (AF). PATIENTS AND METHODS: The AF risk score was developed based on the summed odds ratios (ORs) for AF development of 7 accepted clinical risk factors. The AF risk score is intended to assess the risk of AF similar to how the CHA2DS2-VASc score assesses stroke risk. Seven validated risk factors for AF were used to develop the AF risk score: age, coronary artery disease, diabetes mellitus, sex, heart failure, hypertension, and valvular disease. The AF risk score was tested within a random population sample of the Intermountain Healthcare outpatient database. Outcomes were stratified by AF risk score for OR and Kaplan-Meier analysis. RESULTS: A total of 100,000 patient records with an index follow-up from January 1, 2002, through December 31, 2007, were selected and followed up for the development of AF through the time of this analysis, May 13, 2013, through September 6, 2013. Mean ± SD follow-up time was 3106±819 days. The ORs of subsequent AF diagnosis of patients with AF risk scores of 1, 2, 3, 4, and 5 or higher were 3.05, 12.9, 22.8, 34.0, and 48.0, respectively. The area under the curve statistic for the AF risk score was 0.812 (95% CI, 0.805-0.820). CONCLUSION: We developed a simple AF risk score made up of common clinical factors that may be useful to possibly select patients for long-term monitoring for AF detection.

Radiofrequency ablation of drug refractory ventricular tachycardia related to cocaine use: a feasibility, safety, and efficacy study.

BACKGROUND: Cocaine use is a known but rare cause of cardiac arrhythmias. Ventricular arrhythmias related to cocaine may not respond to antiarrhythmic drugs and may need treatment with radiofrequency ablation. OBJECTIVES: We describe the clinical and electrophysiological characteristics of cocaine-related ventricular tachycardia (VT) from a multicenter registry. METHODS: Subjects presenting with VT related to cocaine use and being considered for radiofrequency ablation have been included in the study. Patients who were refractory to maximal medical therapy underwent radiofrequency ablation of the VT. Clinical, procedural variables, efficacy, and safety outcomes were assessed. RESULTS: A total of 14 subjects met study criteria (age 44 ± 13, range 18- to 68-year-old with 79% male, 71% Caucasian). MRI showed evidence of scar only in 43% of patients (6/14). The mechanism of VT was focal in 50% (n = 7) and scar related reentry in 50% (n = 7) based on 3D mapping. The mean VT cycle length was 429 ± 96 milliseconds. The site of origin was epicardial in 16% (3/18) of VTs. Most clinical VTs were hemodynamically stable (75%). Mean ejection fraction at the time of admission was 44 ± 14%. Duration of procedure was 289 ± 50 minutes. One subject developed pericardial tamponade requiring drainage. At 18 ± 11 months follow-up, freedom from arrhythmia was seen in 86% (1 case lost to follow-up and 2 died). CONCLUSION: Radiofrequency ablation is not only feasible but also safe and effective in patients who have drug refractory VT related to chronic cocaine use.

Percutaneous left ventricular assist devices in ventricular tachycardia ablation: multicenter experience.

BACKGROUND: Data on relative safety, efficacy, and role of different percutaneous left ventricular assist devices for hemodynamic support during the ventricular tachycardia (VT) ablation procedure are limited. METHODS AND RESULTS: We performed a multicenter, observational study from a prospective registry including all consecutive patients (N=66) undergoing VT ablation with a percutaneous left ventricular assist devices in 6 centers in the United States. Patients with intra-aortic balloon pump (IABP group; N=22) were compared with patients with either an Impella or a TandemHeart device (non-IABP group; N=44). There were no significant differences in the baseline characteristics between both the groups. In non-IABP group (1) more patients could undergo entrainment/activation mapping (82% versus 59%; P=0.046), (2) more number of unstable VTs could be mapped and ablated per patient (1.05±0.78 versus 0.32±0.48; P<0.001), (3) more number of VTs could be terminated by ablation (1.59±1.0 versus 0.91±0.81; P=0.007), and (4) fewer VTs were terminated with rescue shocks (1.9±2.2 versus 3.0±1.5; P=0.049) when compared with IABP group. Complications of the procedure trended to be more in the non-IABP group when compared with those in the IABP group (32% versus 14%; P=0.143). Intermediate term outcomes (mortality and VT recurrence) during 12±5-month follow-up were not different between both groups. Left ventricular ejection fraction ≤15% was a strong and independent predictor of in-hospital mortality (53% versus 4%; P<0.001). CONCLUSIONS: Impella and TandemHeart use in VT ablation facilitates extensive activation mapping of several unstable VTs and requires fewer rescue shocks during the procedure when compared with using IABP.

Patients treated with catheter ablation for ventricular tachycardia after an ICD shock have lower long-term rates of death and heart failure hospitalization than do patients treated with medical management only.

BACKGROUND: Ventricular arrhythmias in patients with implantable cardioverter-defibrillators (ICDs) adversely affect outcomes. Antiarrhythmic approaches to ventricular tachycardia (VT) have variable efficacy and may increase risk of ventricular arrhythmias, worsening cardiomyopathy, and death. Comparatively, VT ablation is an alternative approach that may favorably affect outcomes. OBJECTIVE: To further explore the effect on long-term outcomes after catheter ablation of VT, we compared patients with history of ICD shocks who did not undergo ablation, patients with a history of ICD shocks that underwent ablation, and patients with ICDs who had no history of ICD shocks. METHODS: A total of 102 consecutive patients with structural heart disease who underwent VT ablation for recurrent ICD shocks were compared with 2088 patients with ICDs and no history of appropriate shocks and 817 patients with ICDs and a history of appropriate shocks for VT or ventricular fibrillation. Outcomes considered were mortality, heart failure hospitalization, atrial fibrillation, and stroke/transient ischemic attack. RESULTS: The mean age of 3007 patients was 65.4 ± 13.9 years. Over long-term follow-up, 866 (28.8%) died, 681 (22.7%) had a heart failure admission, 706 (23.5%) developed new-onset atrial fibrillation, and 224 (7.5%) had a stroke. The multivariate-adjusted risks of deaths and heart failure hospitalizations were higher in patients with history of ICD shocks who were treated medically than in patients with ICDs and no history of shock (hazard ratio [HR] 1.45; P < .0001 vs HR 2.00; P < .0001, respectively). The multivariate-adjusted risks were attenuated after VT ablation with death and heart failure hospitalization rates similar to those of patients with no shock (HR 0.89; P = .58 vs HR 1.38; P = .09, respectively). A similar nonsignificant trend was seen with stroke/transient ischemic attack. CONCLUSIONS: Patients treated with VT ablation after an ICD shock have a significantly lower risk of death and heart failure hospitalization than did patients managed medically only. The adverse event rates after VT ablation were similar to those of patients with ICDs but without VT.

Initial Experience with A Novel Flexible-Tip Irrigated Ablation Catheter in a Case of Paroxysmal Atrial Fibrillation.

AF ablation can be curative or reduce the symptoms of AF. However, success rates are suboptimal while procedure times can be long. Since AF ablation depends on excellent tip to tissue contact, ease of use and signal quality, a new ablation catheter (FlexAbilityTM Ablation Catheter, St Jude Medical, St Paul, MN) was designed for use during complex ablation. We report an initial case of its use during paroxysmal AF.