Comparison of efficiency of PFA catheter designs by computer modeling.

INTRODUCTION: Various catheter designs are appearing for Pulsed Field Ablation (PFA). It is unclear if they differ in terms of safety and efficiency. PFA studies have reported hemolysis, kidney injury, high troponin, among other side effects. METHODS: Using a CT-derived computer model, we compared catheter designs using two metrics: (1) efficiency: power delivered to an atrial wall target, expressed as a percent of total generator power; and (2) safety: electric current to achieve 90% transmurality (since more energy causes more collateral effects), as well as the corresponding electrode current density (ECD), a heat and bubble metric. The following catheter designs were compared: penta-spline basket, Nitinol spheres (focal 9 mm and large 1-shot), circular, balloon, and flex-circuit. Target was a 6 × 47 mm circumferential segment of atrial wall at LPV antrum. Transmurality was defined as percent of target having >600 volts per centimeter (V/cm) electric field needed for electroporation. RESULTS: Efficiency was 0.9, 1.4, 2.7, 5.9, 10, and 12% for the large 1-shot and 9 mm Nitinol spheres, penta-spline, circular, flex spline, and balloon catheters, respectively. Regarding safety, currents for 90% transmurality were 70, 39,36,12.5, 5.3, and 4 Amps for the same respective catheters, with less being safer. ECD was 124, 25, 74, 83, 41, and 31 A/cm2, respectively. CONCLUSION: Computer models demonstrated a remarkable range in efficiency among catheters studied. Those having less atrial blood exposure had the highest efficiencies, with factors of up to 13X more efficiency compared to exposed ones. Higher efficiency designs have less collateral current and are safer. Confirmatory in-vivo studies are required.

Multicenter experience with andexanet alfa for refractory pericardial bleeding during catheter ablation of atrial fibrillation.

INTRODUCTION: Pericardial bleeding is a rare but life-threatening complication of atrial fibrillation (AF) ablation. Patients taking uninterrupted oral anticoagulation (AC) may be at increased risk for refractory bleeding despite pericardiocentesis and administration of protamine. In such cases, andexanet alfa can be given to reverse rivaroxaban or apixaban. In this study, we aim to describe the rate of acute hemostasis and thromboembolic complications with andexanet for refractory pericardial bleeding during AF ablation. METHODS AND RESULTS: In this multicenter, case series, participating centers identified patients who received a dose of apixaban or rivaroxaban within 24 h of AF ablation, developed refractory pericardial bleeding during the procedure despite pericardiocentesis and administration of protamine and received andexanet. Eleven patients met inclusion criteria, with mean age of 73.5 ± 5.3 years and median CHA2 DS2 -VASc score 4 [3-5]. All patients received protamine and pericardiocentesis, and 9 (82%) received blood products. All patients received a bolus of andexanet followed, in all but one, by a 2-h infusion. Acute hemostasis was achieved in eight patients (73%) while three required emergent surgery. One patient (9%) experienced acute ST-elevation myocardial infarction after receiving andexanet. Therapeutic AC was restarted after a mean of 2.2 ± 1.9 days and oral AC was restarted after a mean of 2.9 ± 1.6 days, with no recurrent bleeding. CONCLUSION: In patients on uninterrupted apixaban or rivaroxaban, who develop refractory pericardial bleeding during AF ablation, andexanet can achieve hemostasis thereby avoiding the need for emergent surgery. However, there is a risk of thromboembolism following administration.

Outcome of high-power short-duration radiofrequency ablation in combination with half-normal saline irrigation for the treatment of atrial fibrillation.

BACKGROUND: Data regarding the use of high-power short-duration (HPSD) radiofrequency (RF) in combination with half-normal saline irrigation for catheter irrigation are limited. OBJECTIVES: This study investigated the safety and efficacy of using HPSD RF ablation in combination with half-normal saline irrigation for the treatment of AF. METHODS: One hundred consecutive patients with AF underwent RF ablation using HPSD combined with half-normal saline for catheter irrigation. In addition, the following ablation strategies were used: 1 mm tags for the display of ablation lesions on the mapping system, high-frequency jet ventilation (HFJV), low contact force, pacing after ablation to verify areas of noncapture, atrial/ventricular pacing at 500 to 700 ms to aid in catheter stability, use of two skin electrodes to reduce impedance, and postablation adenosine infusion. Power was started at 40 to 45 W and was modulated manually based on impedance changes. RESULTS: The average age of patients was 65.2 years and 70% were male. Forty seven percent had paroxysmal AF and the average CHA2 DS2 -VASc score was 2.1 ± 1.6. The average power and lesion duration were 38.1 ± 3.3 W and 8.1 ± 2.3 s, respectively. During a median follow-up period of 321 ± 139 days, 89% of the patients remained free from any atrial arrhythmias after a single RF ablation procedure. No procedure-related death, stroke, pericardial effusion, or atrioesophageal fistula occurred during follow-up. CONCLUSIONS: Catheter ablation using HPSD RF lesions in combination with half-normal saline irrigation and is safe and effective, and results in high rate of freedom from AF.

Ventricular arrhythmia ablation in the presence of mechanical valve utilization and complications of catheter ablation for ventricular arrhythmia in patients with mechanical prosthetic valves.

BACKGROUND: Catheter ablation (CA) for ventricular arrhythmias (VAs) is increasingly utilized in recent years. We aimed to investigate the nationwide trends in utilization and procedural complications of CA for VAs in patients with mechanical valve (MV) prosthesis. METHODS: We drew data from the US National Inpatient Sample database to identify cases of VA ablations, including premature ventricular contraction and ventricular tachycardia, in patients with MVs, between 2003 and 2015. Sociodemographic and clinical data were collected and the incidence of catheter ablation complications, mortality, and length of stay were analyzed. We compared the outcomes to a propensity-matched cohort of patients without prior valve surgery. RESULTS: The study population included a weighted total of 647 CA cases in patients with prior MVs. The annual number of ablations almost doubled, from 34 ablations on average during the "early years" (2003-2008) to 64 on average during the "late years" (2009-2015) of the study (p = .001). Length of stay at the hospital did not differ significantly between patients with MVs and 649 matched patients without prior MVs (5.4 ± 0.4, 4.7 ± 0.3 days, respectively, p = .12). The data revealed a trend toward a higher incidence of complications (12.6% vs. 7.5% respectively, p = .14) and mortality (3.7% vs. 0.7%, respectively, p = .087) among patients with MVs compared to the matched control group, not reaching statistical significance. CONCLUSION: The data show increased utilization of VA ablations in patients with MVs and a trend toward a higher incidence of in-hospital mortality and complications compared to the propensity-matched control group without MVs.

Management of patients with interrupted inferior vena cava requiring electrophysiology procedures.

BACKGROUND: Interrupted inferior vena cava (IVC) is a rare venous anomaly that complicates the treatment of patients who require electrophysiology (EP) procedures. METHODS: We describe five consecutive cases of patients with interrupted IVC who presented to the EP laboratory requiring interventional procedures including catheter ablation for atrial fibrillation and supraventricular tachycardia and left atrial appendage closure. All cases were successfully completed utilizing a variety of approaches to vascular access including transseptal puncture via transhepatic and internal jugular approaches. CONCLUSION: Procedures in the EP lab can be performed successfully in patients with interrupted IVC.

Ventricular Fibrillation Conversion Testing After Implantation of a Subcutaneous Implantable Cardioverter Defibrillator: Report From the National Cardiovascular Data Registry.

BACKGROUND: Compared with transvenous implantable cardioverter defibrillators (ICDs), subcutaneous (S)-ICDs require a higher energy for effective defibrillation. Although ventricular fibrillation conversion testing (CT) is recommended after S-ICD implantation to ensure an adequate margin between the defibrillation threshold and maximum device output (80J), prior work found that adherence to this recommendation is declining. METHODS: We studied first-time recipients of S-ICDs (between September 28, 2012, and April 1, 2016) in the National Cardiovascular Database Registry ICD Registry to determine predictors of use of CT, predictors of an insufficient safety margin (ISM, defined as ventricular fibrillation conversion energy >65J) during testing, and inhospital outcomes associated with use of CT. Multivariable logistic regression analysis was used to predict use of CT and ISM. Inverse probability weighted logistic regression analysis was used to examine the association between use of CT and inhospital adverse events including death. RESULTS: CT testing was performed in 70.7% (n=5624) of 7960 patients with S-ICDs. Although deferral of CT was associated with several patient characteristics (including increased body mass index, increased body surface area, severely reduced ejection fraction, dialysis dependence, warfarin use, anemia, and hypertrophic cardiomyopathy), the facility effect was comparatively more important (area under the curve for patient level versus generalized linear mixed model: 0.619 versus 0.877). An ISM occurred in 6.9% (n=336) of 4864 patients without a prior ICD and was more common among white patients and those with ventricular pacing on the preimplant ECG, higher preimplant blood pressure, larger body surface area, higher body mass index, and lower ejection fraction. A risk score was able to identify patients at low (<5%), medium (5% to 10%), and high risk (>10%) for ISM. CT testing was not associated with a composite of inhospital complications including death. CONCLUSIONS: Use of CT testing after S-ICD implantation was driven by facility preference to a greater extent than patient factors and was not associated with a composite of inhospital complications or death. ISM was relatively uncommon and is associated with several widely available patient characteristics. These data may inform ICD system selection and a targeted approach to CT.

A comparison of postprocedural anticoagulation in high-risk patients undergoing WATCHMAN device implantation.

BACKGROUND: Left atrial appendage closure (LAAC) is an alternative to long-term anticoagulation for thromboembolic protection in patients with atrial fibrillation (AF) and high bleeding risk. Short-term Warfarin use following LAAC is well-studied, while data pertaining to novel oral anticoagulant (NOAC) use in this setting is less robust. Specifically, data regarding the safety and efficacy of postprocedural NOAC use in high-risk patients is lacking. OBJECTIVE: To compare the safety and efficacy of Warfarin and NOAC use in a high-risk patient population undergoing LAAC with the WATCHMAN device. METHODS: From November 2015 to October 2017, 97 patients underwent LAAC with the WATCHMAN device. All patients were discussed at a multidisciplinary meeting prior to device implantation. Longitudinal data were collected and analyzed for a composite endpoint of stroke and death at 8 months, and major bleeding at 3 and 6 months. RESULTS: Among the 90 patients included in the safety and efficacy analysis, 43 were prescribed Warfarin and 47 were prescribed NOACs. Baseline characteristics were comparable between study groups. There were no procedural complications and no significant differences in the incidence of death and stroke at 8 months or major bleeding at 3 and 6 months. CONCLUSION: For patients with AF at high risk of both thromboembolic and hemorrhagic events, NOACs as compared to Warfarin, seem to be safe and effective for short-term anticoagulation following LAAC with the WATCHMAN device. Further validation in large randomized controlled trials is required.

Percutaneous left atrial appendage occlusion in the prevention of stroke in atrial fibrillation: a systematic review.

Atrial fibrillation is commonly coexistent with heart failure, and the management of the heart failure patient would be incomplete without an appreciation for atrial fibrillation management. There are many complications associated with oral anticoagulation in the prevention of stroke related to atrial fibrillation. In recent years, the advent of several percutaneous left atrial appendage (LAA) occlusion/closure strategies has sought to provide an alternative treatment modality. Here, we systematically review the published literature to investigate the efficacy and safety of percutaneous LAA occlusion/closure devices. We searched PubMed, EMBASE, Cochrane database of systematic reviews, and the FDA Medical Devices database. Using prespecified criteria, we identified studies of the Amplatzer Cardiac Plug (St. Jude Medical), Amplatzer Amulet (St. Jude Medical), Lariat suture delivery device (SentreHeart), and Watchman device (Boston Scientific). We analyzed 2 randomized controlled trials (RCT) and 15 non-randomized registries that satisfied the study criteria. The two RCT both studied the Watchman device versus standard warfarin therapy; the studies indicate that the Watchman may be non-inferior to warfarin. Long-term efficacy outcomes for the Watchman device are promising. Data regarding the Amplatzer Cardiac Plug, Amplatzer Amulet, and Lariat suture delivery device are limited by the paucity of RCT data. High-quality prospective research is needed to directly compare LAA occlusion/closure strategies against one another as well as versus the direct oral anticoagulation medications. Data regarding the role of LAA occlusion in the heart failure population are lacking.

Safety and efficacy of delivering high-power short-duration radiofrequency ablation lesions utilizing a novel temperature sensing technology.

Aims: Delivery of high-power short-duration radiofrequency (RF) ablation lesions is not commonly used, in part because conventional thermocouple (TC) technology underestimates tissue temperature, increasing the risk of steam pop, and thrombus formation. We aimed to test whether utilization of an ablation catheter equipped with a highly accurate novel TC technology could facilitate safe and effective delivery of high-power RF lesions. Methods and results: Adult male Yorkshire swine were used for the study. High-power short-duration ablations (10-s total; 90 W for 4 s followed by 50 W for 6 s) were delivered using an irrigated force sensing catheter, equipped with six miniature TC sensors embedded in the tip electrode shell. Power modulation was automatically performed when the temperature reached 65°C. Ablation parameters were recorded and histopathological analysis was performed to assess lesion formation. One hundred and fourteen RF applications, delivered using the study ablation protocol in the ventricles of eight swine [53 in the right ventricle (RV), 61 in the left ventricle (LV)], were analysed. Average power delivered was 55.4 ± 5.3 W and none of the ablations resulted in a steam pop. Fourteen out of the 114 (12.3%) lesions were transmural. The mean lesion depth was 3.9 ± 1.1 mm for the 100 non-transmural lesions. Similar ablation parameters resulted in bigger impedance drop (11.6 Ω vs. 9.1 Ω, P = 0.009) and deeper lesions in the LV compared with the RV (4.3 ± 1.2 mm vs. 3.3 ± 0.8 mm, P < 0.001). Conclusion: Delivery of high-power short-duration RF energy applications, facilitated by a novel ablation catheter system equipped with advanced TC technology, is feasible, safe, and results in the formation of effective ablation lesions.

Retrospective review of 65 atrioesophageal fistulas post atrial fibrillation ablation.

BACKGROUND: Although a rare complication of catheter based ablation for atrial fibrillation (AF), atrioesophageal fistula (AEF) is a serious and fatal event [1-5]. Most reports of AEF are single cases or small case series. OBJECTIVE: The purpose of this study was to perform a comprehensive literature search of all published atrioesophageal fistula following catheter ablation for AF in order to identify the mortality rates associated with therapeutic modalities and suggest the most definitive management in reducing mortality. METHODS: A comprehensive literature review of reported observational cases of atrioesophageal fistula post catheter based ablation for atrial fibrillation was performed. RESULTS: Sixty-five cases of AEF post atrial fibrillation ablation were reviewed. The mean age was 55 years old. 73.8% (48/65) of the identified cases occurred in males (p < 0.001). Of the 65 cases, 13 underwent surgical radiofrequency ablation (RFA) and 52 underwent percutaneous RFA. Mortality resulted in 53.8% of those who underwent surgical RFA and in 55.8% of those who underwent percutaneous RFA (p = .888). The time range interval from procedure to onset of symptoms was 1-60 days. The most prevalent symptom, fever, occurred in 52 of the 65 cases, followed by neurological symptoms (n = 44). CT of the chest (n = 37), transthoracic echocardiogram (n = 21), and CT of the head (n = 18) were the preferred diagnostic modalities. Patients who underwent surgical correction with esophageal repair for treatment were more likely to survive, in comparison to patients who were treated with non-surgical interventions, such as antibiotic therapy, anticoagulation therapy or esophageal stenting. Of the total 34 patients who were treated surgically, 27 survived (79.4%). Of the total 31 patients who were treated non-surgically, only 2 survived (6.5%), reflecting significantly lower mortality with surgical versus non-surgical therapy (p < 0.001). CONCLUSION: Atrioesophageal fistula is an uncommon but potentially fatal complication of atrial fibrillation ablation. Patients who underwent surgical repair were twelve times more likely to survive than those treated with stenting, antibiotic therapy or no intervention. Based on the observation that patients are 12 times more likely to survive an AEF with surgery than without, the authors believe that prompt surgical correction of AEF should be considered as standard of care when dealing with this dreaded complication.

Termination of persistent atrial fibrillation during pulmonary vein isolation: insight from the MAGIC-AF trial.

AIMS: Controversy on the optimal ablation strategy for persistent atrial fibrillation (AF) exists with limited work evaluating a strategy of pulmonary vein isolation (PVI) alone when AF terminates during PVI. Thirty-five patients had AF termination during PVI in the Modified Ablation Guided by Ibutilide Use in Chronic Atrial Fibrillation (MAGIC-AF; ClinicalTrials.gov number: NCT01014741) study. The objective of the current study is to report the 1-year outcome after PVI alone in this unique patient group. METHODS AND RESULTS: The 1-year single procedure freedom from atrial arrhythmia off anti-arrhythmic drugs was reported for the 35 patients in the MAGIC-AF study with persistent AF termination during or upon completion of PVI. Freedom from recurrent atrial arrhythmia was achieved in 60% of patients where AF terminated during PVI. Cavotricuspid isthmus flutter was common when AF terminated to a macro re-entrant flutter during PVI, and responsible for 92% of all flutter circuits with AF termination. CONCLUSIONS: Persistent AF termination during PVI may identify a subgroup of patients who experience a similar long-term clinical outcome with PVI ablation alone when compared with other more extensive persistent AF ablation strategies. Pulmonary vein isolation alone may be an appropriate tactic in this subgroup of persistent AF patients.

Impact of treatment crossovers on clinical outcomes in the rate and rhythm control strategies for atrial fibrillation: Insights from the AFFIRM (Atrial Fibrillation Follow-up Investigation of Rhythm Management) trial.

We investigated the rates and reasons for crossover to alternative treatment strategies and its impact on mortality in patients who were enrolled in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial. Over a mean follow-up period of 3.5 years, 842 patients underwent crossover to the alternative treatment arms in AFFIRM. The rate of crossover from rhythm to rate control (594/2,033, 29.2%) was more frequent than the rate of crossover from rate to rhythm control (248/2,027, 12.2%, P < 0.0001). The leading reasons for crossover from rhythm to rate control were failure to achieve or maintain sinus rhythm (272/594, 45.8%) and intolerable adverse effects (122/594, 20.5%). In comparison, the major reasons for crossover from rate to rhythm control were failure to control atrial fibrillation symptoms (159/248, 64.1%) and intolerable adverse effects (9/248, 3.6%). This difference in crossover pattern was statistically significant (P < 0.0001). There was a significantly decreased risk of all-cause mortality (adjusted HR: 0.61, 95% CI: 0.48-0.78, P < 0.0001) and cardiac mortality (adjusted hazard ratio [HR]: 0.61, 95% confidence interval [CI]: 0.43-0.88, P = 0.008) in the subgroup of patients who crossed over from rhythm to rate control as compared to those who continued in rhythm control. There was a nonsignificant trend toward decreased all-cause (adjusted HR: 0.76, 95% CI: 0.53-1.10, P = 0.14) and cardiac mortality (adjusted HR: 0.70, 95% CI: 0.42-1.18, P = 0.18) in patients who crossed over from rate to rhythm control as compared to those who continued rate control.

The modified stepwise ablation guided by low-dose ibutilide in chronic atrial fibrillation trial (The MAGIC-AF Study).

AIMS: Complex fractionated atrial electrograms (CFAE) are targeted during persistent atrial fibrillation (AF) ablation. However, many CFAE sites are non-specific resulting in extensive ablation. Ibutilide has been shown to reduce left atrial surface area exhibiting CFAE. We hypothesized that ibutilide administration prior to CFAE ablation would identify sites critical for persistent AF maintenance allowing for improved procedural efficacy and long-term freedom from atrial arrhythmias. METHODS AND RESULTS: Two hundred patients undergoing a first-ever persistent AF catheter ablation procedure were randomly assigned to receive either 0.25 mg of intravenous ibutilide or saline placebo upon completion of pulmonary vein isolation. Complex fractionated atrial electrogram sites were then targeted with ablation. The primary efficacy endpoint was the 1-year single procedure freedom from atrial arrhythmia off anti-arrhythmic drugs. Similar procedural characteristics (procedure, fluoroscopy, and ablation times) were observed with both strategies despite a greater reduction in left atrial surface area with CFAE sites (8 vs. 1%, P < 0.0001) and AF termination during CFAE ablation with ibutilide compared with placebo (75 vs. 57%, P = 0.007). The primary efficacy endpoint was achieved in 56% of patients receiving ibutilide and 49% receiving placebo (P = 0.35). No significant differences in peri-procedural complications were observed in both groups. CONCLUSION: Despite a reduction in CFAE area and greater AF termination during CFAE ablation, procedural characteristics and clinical outcomes were unchanged when CFAE ablation was guided by ibutilide administration. CLINICAL TRIAL REGISTRATION INFORMATION: ClinicalTrials.gov number: NCT01014741.

A Novel Annotation Technique During Mapping to Facilitate the Termination of Atrial Tachycardia Following Ablation for Atrial Fibrillation.

INTRODUCTION: The treatment of atrial tachycardia (AT) occurring after ablation for atrial fibrillation (AF) is challenging. The most common ablation strategy relies on entrainment, and electroanatomic activation mapping (EAM) using a conventional window of interest (WOI), centered on the easily detectable atrial signal on the coronary sinus catheter. We describe a novel EAM annotation technique that uses a WOI starting 40 milliseconds prior to the P wave in order to detect the reentrant AT exit site. This WOI timing is based on the similarity between scar-related reentrant AT and scar-related ventricular tachycardia. METHODS: Patients with AT after prior ablation for AF were included. The EAM of the AT was performed using the novel mapping annotation technique. The ablation was considered successful if the AT terminated during ablation at the site identified by this strategy. RESULTS: Twenty-eight patients with 36 ATs were included. The ATs were classified as follows: mitral annulus (13/36), roof (11/36), anterior/posterior/lateral left atrial wall (10/36), and RA (2/36). A complete EAM using the novel annotation technique was achieved in 34 of 36 AT's, encompassing 94 ± 6.5% of the cycle length. Low amplitude pre-P fractionated electrograms were found in 34 of 36 (94%) ATs and these occurred at a mean distance of 1.8 ± 1.2 mm from the "early-meets-late" line. Ablation at these areas resulted in termination of 34 of 36 ATs (94%). CONCLUSION: The novel EAM annotation allows the accurate detection of the critical isthmus of post-AF ablation AT. Ablation of these isthmuses results in termination of the AT in the vast majority of patients.

Persistent Atrial Fibrillation Ablation in Females: Insight from the MAGIC-AF Trial.

INTRODUCTION: Atrial fibrillation (AF) ablation is less frequently performed in women when compared to men. There are conflicting data on the safety and efficacy of AF ablation in women. The objective of this study was to compare the clinical characteristics and outcomes in a contemporary cohort of men and women undergoing persistent AF ablation procedures. METHODS AND RESULTS: A total of 182 men and 53 women undergoing a first-ever persistent AF catheter ablation procedure in The Modified Ablation Guided by Ibutilide Use in Chronic Atrial Fibrillation (MAGIC-AF) trial were evaluated. Clinical and procedural characteristics were compared between each gender. The primary efficacy endpoint was the 1-year single procedure freedom from atrial arrhythmia off anti-arrhythmic drugs. Women undergoing catheter ablation procedures were older than men (P < 0.001). The duration of AF and associated co-morbidities were similar between both genders. Single procedure drug-free atrial arrhythmia recurrence occurred in 53% of the cohort with no difference based on gender (men = 54%, women = 53%; P = 1.0). Procedural (P = 0.04), fluoroscopic (P = 0.02), and ablation times (P = 0.003) were shorter in women compared to men. Periprocedural complications and postablation improvement in quality of life were similar between men and women. CONCLUSION: Women undergoing a first-ever persistent AF ablation procedure were older but had similar clinical outcomes and complications when compared with men.

Association between Heat Shock Protein-60 and Development of Atrial Fibrillation: Results from the Multi-Ethnic Study of Atherosclerosis (MESA).

BACKGROUND: During atrial fibrillation (AF), a high rate of myocyte activation causes cellular stress and initiates the process of atrial remodeling, which further promotes persistence of AF. Although heat shock proteins (HSPs) have been shown to prevent atrial remodeling and suppress the occurrence of AF in cellular and animal experimental models, increased levels of HSP-60 have been observed in patients with postoperative AF, likely reflecting a response to cellular stress. To better understand the role of HSP-60 in relation to AF, we examined the association of HSP-60 levels in relation to the future development of AF in the Multi-Ethnic Study of Atherosclerosis (MESA). METHODS: MESA is a cohort study that recruited 6,814 participants aged 45-84 years and free of known cardiovascular disease at baseline (2000-2002) from six field centers. We investigated 983 participants, selected at random from the total cohort, who had HSP-60 measured and were free of AF at baseline. We tested the association of HSP-60 levels with the incidence of AF using multivariate Cox models after adjustment for demographics, clinical characteristics, and biomarkers. RESULTS: During an average of 10.6 years of follow-up, 77 participants developed AF. We did not observe a significant association between the log-transformed HSP-60 levels and development of AF on either unadjusted or multivariate analysis (adjusted hazard ratio: 1.02 per unit difference on natural log scale, 95% confidence interval: 0.77-1.34 ln (ng/mL). CONCLUSION: Contrary to the findings from the preclinical studies, which demonstrated an important role of HSP-60 in the pathogenesis of AF, we did not observe a significant association between HSP-60 and occurrence of AF.

Novel Technique to Prevent Phrenic Nerve Injury During Pulmonary Vein Isolation Using Preprocedural Imaging.

INTRODUCTION: Phrenic nerve (PN) injury is one of the major complications of pulmonary vein isolation (PVI). Pace mapping for PN capture is routinely used to identify areas with high risk for injury along the anterior border of the right pulmonary veins (PVs). Our aim was to evaluate the feasibility of using preprocedural imaging to identify areas where no PN capture is possible along the anterior border of the right PVs, thus avoiding the need for pace mapping during PVI. METHODS AND RESULTS: It was hypothesized that PN capture along the anterior border of the right PVs does not occur in the area where the right and left atria overlap. Three-dimensional segmentation of both atria was performed on preprocedural magnetic resonance and computed tomography angiograms in 40 patients before undergoing PVI. The area of overlap between the right and left atria was delineated. Image registration was performed during the procedure. Using pacing, regions with and without PN capture were marked along the anterior border of the right PVs. A total of 361 points were tested for PN stimulation (9 ± 4 points/patient). PN capture occurred in 97 out of the 189 points (51%) in the area with no overlap between the right and left atria. No PN capture occurred in the area of overlap (172 points, P< 0.001). CONCLUSION: Delineation of the area of overlap between the right and left atria derived from preprocedural imaging reliably identifies regions where PN pace capture does not occur. Testing for PN stimulation before ablation may not be necessary in these regions.

3D cardiovascular navigation system: accuracy and reduction in radiation exposure in left ventricular lead implant.

INTRODUCTION: Cardiac resynchronization therapy implants entail significant radiation exposure for patients and physicians. A novel 3D electromagnetic cardiovascular navigation system (MediGuide™) was designed to superimpose the real-time location of sensors embedded in delivery tools on prerecorded coronary sinus (CS) venograms while adjusting for patient movement and variations in heart rate under different C-arm angulations. We studied the accuracy and efficacy of MediGuide™ in reducing radiation exposure during LV lead implants. METHODS AND RESULTS: Fluoroscopy durations and radiation exposures were measured in 6 canines undergoing both conventional and MediGuide™-guided LV lead implants. The in vivo accuracy of MediGuide™ was evaluated by obtaining CS venograms at 3 different C-arm angulations at 3 different heart rates and measuring the separation between the projected sensor icon of a MediGuide™ sensor-enabled guidewire and the encompassing branch on prerecorded venograms. RESULTS: Mediguide™-guided implants resulted in significant reductions in fluoroscopy time (52 ± 120 [median 6] vs 129 ± 118 [median 90] sec, P < 0.001) and radiation exposure (13.8 ± 32.4 [median 1.7] vs 49.2 ± 45.3 [median 27.2] µGym(2) , P = 0.03) compared to conventional implants. LV lead delivery time was not significantly different between the 2 implant techniques (P = 0.27). The mean separation between the projected guidewire sensor icon and its encompassing branch was 0.48 ± 0.94 (median 0.00) mm. System accuracy was not affected by variations in heart rate or C-arm angulations. CONCLUSION: The novel 3D cardiovascular navigation system enabled accurate and reliable tracking of sensor-enabled tools at varying heart rates and C-arm angulations with minimal need for fluoroscopy guidance, significantly reducing fluoroscopy time and radiation exposure.

Impact of catheter ablation on P-wave parameters on 12-lead electrocardiogram in patients with atrial fibrillation.

BACKGROUND: Catheter ablation has emerged as a widely used treatment modality for atrial fibrillation (AF). P-wave abnormalities have been described in the patients with AF, and catheter ablation may potentially further impact P-wave parameters due to ablation of atrial tissue. METHODS: We reviewed data on P-wave parameters (P-wave duration, amplitude and P-wave duration and amplitude product) in leads V1 and aVF and changes in the P-terminal force (Ptf; product of duration and amplitude of terminal part of P-wave) in lead V1 from 12-lead electrocardiograms obtained prior to and after CA of a total of 46 (28 paroxysmal and 18 persistent) AF patients. RESULTS: The median age of patients in our study was 63 (range: 30-77) years. We noticed a significant reduction in the P-wave duration (from 87.39±28.62ms at baseline to 72.09±24.59ms; p=0.0072) and the product of P-wave duration and amplitude in lead V1 (12.16±5.54mVms at baseline to 8.30±5.78mVms, p=0.0015) after CA. There was also a significant decrease in P-wave duration (from 92.57±19.67ms at baseline to 76.48±16.32ms after CA, p=0.0001) and P-wave duration and amplitude product in lead aVF (12.61±4.05mVms at baseline to 9.77±3.86mVms after CA, p=0.0001). CA also led to a significant decrease in Ptf (from 4.56±1.88 at baseline to 2.85±1.42mVms, p<0.0001). CONCLUSION: Radiofrequency catheter ablation of AF leads to modification of P-wave parameters with substantial diminution in both the amplitude and duration of the P-wave in leads V1 and aVF. This likely represents reduction in electrically active atrial tissue after ablation, and may serve as a marker for the extent of ablated atrial tissue.