Faculty Bibliography

Background: Biophysical markers of effective lesion formation during radiofrequency (RF) ablation include impedance decline, stable catheter-tissue contact and local unipolar electrogram change suggesting lesion transmurality The interactions between these factors as well as the implications of lesion sequence are not well understood. Objective: To analyze the impact of catheter stability and lesion sequence on markers of lesion formation during atrial fbrillation (AF) ablation. Methods: Sequential or time-spaced paired RF lesions with goal force-time integral (FTI) 400 gs were placed in prespecifed locations in 20 patients undergoing frst time RF ablation for paroxysmal AF. Custom developed software (MATLAB, Mathworks, USA) was used to extract and analyze lesion data, and 3D catheter position sampled at 60Hz from the CARTO3 mapping system (Biosense Webster, Inc.). All cases were performed using jet ventilation and irrigated force-sensing catheters. Results: 282 ablation lesions were studied, with mean FTI 410.8+/-18.2 gs. Mean impedance decline was greater for the frst lesion in a given pair, 13.6+/-7.9OMEGA vs. 10.7+/-4.6OMEGA, (p < 0.01). Compared to time-spaced lesions, sequential lesions resulted in signifcantly smaller impedance decline (9.8+/-3.8OMEGA vs. 11.8+/-5.2OMEGA, p<0.01), but increased probability of achieving transmurality, as evident by unipolar signal change (68% vs 42% p=0.01). Mean catheter excursion for a single lesion was 0.67+/-0.54mm and maximal catheter excursion was 1.64+/-1.3mm. Ablation catheter spatial stability was found to be inversely related to both amplitude (rho=0.51, p<0.0001) and maximal rate (dI/dT) of impedance decline (rho=0.32, p<0.0001). Conclusion: Lesion sequence and catheter spatial stability were major modifers of impedance change and unipolar electrographic evidence of lesion transmurality during RF ablation. Sequential ablation resulted in transmural lesions more frequently, despite lesser impedance decline. In contrast to previously reported positive association between contact-force and impedance decline, increased ablation catheter spatial stability was associated with lesser impedance decline

Atrial fibrillation is the most common arrhythmia worldwide and is a major risk factor for embolic stroke. In this article, the authors describe the crucial role of two- and three-dimensional transesophageal echocardiography in the pre- and postprocedural assessment and intraprocedural guidance of percutaneous left atrial appendage (LAA) occlusion procedures. Although recent advances have been made in the field of systemic anticoagulation with the novel oral anticoagulants, these medications come with a significant risk for bleeding and are contraindicated in many patients. Because thromboembolism in atrial fibrillation typically arises from thrombi originating in the LAA, surgical and percutaneous LAA exclusion/occlusion techniques have been devised as alternatives to systemic anticoagulation. Currently, surgical LAA exclusion is typically performed as an adjunct to other cardiac surgical procedures, which limits the number of eligible patients. Recently, several percutaneously delivered devices for LAA exclusion from the systemic circulation have been developed, some of which have been shown in clinical trials to reduce the risk for thromboembolism. These devices use an either purely endocardial LAA occlusion approach, such as the Watchman and Amulet procedures, or both an endocardial and a pericardial (epicardial) approach, such as the Lariat procedure. In the Watchman and Amulet procedures, a transseptally delivered structure composed of nitinol is placed in the LAA orifice, thereby excluding the LAA from the systemic circulation. In the Lariat procedure, a magnet link is created between a transseptally delivered endocardial wire and epicardially delivered pericardial wire, followed by epicardial suture ligation of the LAA.

OBJECTIVES/OBJECTIVE:This study sought to investigate the effect of pacing mediated heart rate modulation on catheter-tissue contact and impedance reduction during radiofrequency ablation in human atria during atrial fibrillation (AF) ablation. BACKGROUND:In AF ablation, improved catheter-tissue contact enhances lesion quality and acute pulmonary vein isolation rates. Previous studies demonstrate that catheter-tissue contact varies with ventricular contraction. The authors investigated the impact of modulating heart rate on the consistency of catheter-tissue contact and its effect on lesion quality. METHODS:Twenty patients undergoing paroxysmal AF ablation received ablation lesions at 15 pre-specified locations (12 left atria, 3 right atria). Patients were assigned randomly to undergo rapid atrial pacing for either the first half or the second half of each lesion. Contact force and ablation data with and without pacing were compared for each of the 300 ablation lesions. RESULTS:Compared with lesion delivery without pacing, pacing resulted in reduced contact force variability, as measured by contact force SD, range, maximum, minimum, and time within the pre-specified goal contact force range (p < 0.05). There was no difference in the mean contact force or force-time integral. Reduced contact force variability was associated with a 30% greater decrease in tissue impedance during ablation (p < 0.001). CONCLUSIONS:Pacing induced heart rate acceleration reduces catheter-tissue contact variability, increases the probability of achieving pre-specified catheter-tissue contact endpoints, and enhances impedance reduction during ablation. Modulating heart rate to improve catheter-tissue contact offers a new approach to optimize lesion quality in AF ablation. (The Physiological Effects of Pacing on Catheter Ablation Procedures to Treat Atrial Fibrillation [PEP AF]; NCT02766712).

BACKGROUND: Sarcoidosis is thought to represent a genetically-primed, abnormal immune response to an antigen exposure or inflammatory trigger, with both genetic and environmental factors playing a role in disease onset and phenotypic expression. In a population of firefighters with post-WTC-9/11/2001 (9/11) sarcoidosis, we have a unique opportunity to describe the clinical course of incident sarcoidosis during the 15-years post-exposure and, on average, 8-years after diagnosis. METHODS: Among the WTC-exposed cohort, 74 firefighters with post-9/11 sarcoidosis were identified through medical records review. 59 were enrolled in follow-up studies. For each participant, the World Association of Sarcoidosis and Other Granulomatous Diseases organ assessment tool was used to categorize sarcoidosis involvement of each organ system at time of diagnosis and at follow-up. RESULTS: The incidence of sarcoidosis post-9/11 was 25/100,000. Radiographic resolution of intrathoracic involvement occurred in 24 (45%). Lung function for nearly all was within normal limits. Extrathoracic involvement increased, most prominently joints (15%) and cardiac (16%). There was no evidence for calcium dysmetabolism. Few had ocular (5%) or skin (2%) involvement. None had beryllium sensitization. Most (76%) did not receive any treatment. CONCLUSIONS: Extrathoracic disease was more prevalent in WTC-related sarcoidosis than reported for sarcoidosis patients without WTC-exposure or for other exposure-related granulomatous diseases (beryllium disease and hypersensitivity pneumonitis). Cardiac involvement would have been missed if evaluation stopped after electrocardiogram, 48-hour recordings and echocardiogram. Our results also support the need for advanced cardiac screening in asymptomatic patients with strenuous, stressful, public safety occupations, given the potential fatality of a missed diagnosis.

Background: Pre-procedure time outs are integral to medicine to improve quality and safety. We hypothesized that a radiation safety time out for EP procedures would reduce radiation exposure levels for patients and staff. Objective: To design, implement and assess the effect of a radiation safety time out on radiation exposure in the EP lab. Methods: Baseline data on all adult EP procedures were collected for 6 months prior to implementation of the radiation safety time out. Upon implementation of the time out, data were collected prospectively with analyses to be performed every 3 months for up to 12 months. The primary endpoint was mean dose area product (DAP). Secondary endpoints were reference dose, fluoroscopy time, use of additional shielding, and use of alternative imaging. Results: The study was halted after three months. In total, 592 cases prior to the time out and 448 cases during implementation of the time out were included. Use of the time out resulted in a 22% reduction in the DAP (p = 0.013). The mean reference dose was also reduced by 26%. The use of additional radiation shields and ultrasound imaging for venous access increased significantly during the time out period. These differences remained significant when adjusted for BMI, proceduralist, and procedure type. There was no increase in procedure time or complications with the time out (Table). Conclusion: Implementation of a radiation safety time out significantly reduces radiation exposure during EP procedures. EP laboratories, as well as other areas of medicine that use fluoroscopy, should strongly consider the use of radiation safety time outs to reduce radiation exposures and improve safety. (Table presented)

Background: Analysis of the local unipolar electrogram aids premature ventricular contraction (PVC) localization in catheter ablation of idiopathic, outflow tract PVCs. A unipolar electrogram QS complex may be seen in the region of PVC origin, but the specificity of this finding is low. The unipolar anodal electrode utilized for PVC mapping is typically Wilson central terminal (WCT) or an indifferent electrode placed within the inferior vena cava (IVC). The optimal unipolar electrode selection for unipolar PVC mapping is unknown. Objective: To compare unipolar mapping of idiopathic outflow tract PVCs using WCT to unipolar mapping using an IVC electrode. Methods: PVC mapping and ablation was performed in 20 consecutive patients presenting for first-time ablation of idiopathic, outflow tract PVCs. The unipolar electrode utilized for initial mapping was randomly assigned and blinded to the operator. Mapping was performed using the CARTO 3 mapping system and SmartTouch RF ablation catheter (Biosense Webster, Inc.). Activation mapping and pace-mapping was performed at the discretion of the operator. Locations with a QS complex were annotated on the electroanatomic map. After a complete map was created blinded mapping was repeated with the alternate unipolar electrode prior to RF application. Results: PVCs were localized to the right ventricular outflow tract in 18 patients (90%) and to the left ventricular outflow tract in 2 patients (10%). Complete unipolar mapping could not be completed in 4 of 20 (20%) of cases due to infrequency of PVCs. In the 16 remaining patients, QS complex surface area was significantly larger with WCT than with the IVC electrode (3.11 +/- 1.8 cm² vs. 1.3 +/- 0.8 cm², p < 0.001). The IVC electrode QS area was completely within the WCT QS area in all cases, and the ratio of WCT QS area to IVC electrode QS area was 2.6 +/- 0.8 (range 1.8 to 4.4). The area of RF application at which PVCs were durably suppressed was within the IVC electrode QS area in all patients. Conclusion: Utilization of an indifferent IVC electrode may improve precision and specificity of unipolar mapping in catheter ablation of idiopathic, outflow tract PVCs

Background: Unfavorable outcomes observed with stepwise linear ablation of non-paroxysmal AF (NPAF) in large clinical trials utilizing ablation catheters without contact-force sensing (CFS) may be attributable to pro-arrhythmic effects of incomplete ablation lines. The optimal ablation strategy for catheter ablation of NPAF using a contact force sensing radiofrequency (RF) ablation catheter remains unclear. Objective: To compare catheter ablation outcomes of stepwise linear ablation to left atrial (LA) posterior wall isolation in patients undergoing NPAF ablation using a CFS RF ablation catheter. Methods: We performed pulmonary vein antral isolation (PVAI) followed by isolation of the LA posterior wall in 80 consecutive patients undergoing first-time NPAF ablation between November 2015 and March 2016 (Group 1) and compared clinical outcomes to those of 112 consecutive patients who underwent PVAI followed by step-wise linear ablation for NPAF between May 2014 and November 2015 (Group 2). All ablation procedures were performed using the Carto 3 mapping system and SmartTouch RF ablation catheter (Biosense Webster, Inc.). Arrhythmia recurrence was assessed using 2-week event monitors at 3-month intervals. Arrhythmia-free survival at 12 months was estimated using the Kaplan-Meier method. Results: Baseline characteristics of Group 1 and Group 2 were similar. At 12 months follow-up, arrhythmia-free survival was significantly greater in Group 1 patients compared with Group 2 (81.9% vs. 67.5%, respectively; p=0.0318). There was no significant difference in survival free from AF between group 1 and group 2 (89% vs. 84.1%, respectively; p=0.3431), however group 1 patients developed significantly fewer post-ablation atrial tachycardias (AT) than group 2 patients (8.1% vs 30.1%, respectively; p<0.001). Conclusion: Among patients undergoing NPAF ablation using a contact force sensing RF ablation catheter, LA posterior wall isolation resulted in fewer recurrent atrial arrhythmias than a stepwise linear approach. The reduction in recurrent atrial arrhythmias is driven primarily by a reduction in recurrent AT

Introduction: Large clinical trials have recently demonstrated stepwise linear ablation for non-paroxysmal atrial fibrillation (NPAF) to be inferior to pulmonary vein isolation alone. It is unknown whether the unfavorable outcomes observed in these trials can be attributed to the pro-arrhythmic effects of incomplete ablation lines. We hypothesized that improved lesion quality related to use of contact-force sensing (CFS) ablation catheters would improve procedural outcomes. Methods: We prospectively analyzed procedural outcomes of 74 consecutive patients with NPAF undergoing first-time radiofrequency catheter ablation with a CFS catheter (Smart Touch, Biosense Webster) using a step-wise approach (Group 1). The clinical outcomes of these patients were compared with 74 consecutive patients with NPAF who underwent catheter ablation between September 2013 and June 2014 with a non-contact force sense radiofrequency ablation catheter (Group 2) at a single tertiary care medical center. Arrhythmia recurrence was assessed using 2-week event monitors at 3-month intervals following index ablation. Results: Baseline characteristics of Group 1 and Group 2 were similar, although in Group 1 there was a greater prevalence of patients with persistent NPAF lasting for 6-months or longer prior to initial ablation (43% vs 21%, p=0.071). The recurrence rate at 1 year as estimated by the Kaplan-Meier method was not significantly different between Group 1 and Group 2 (25.7% vs 29.7%, p=0.582). The presenting recurrent arrhythmia was most frequently atrial tachycardia (AT) in both groups (Group 1: n=19, AT 68.4% and AF 31.6% vs Group 2: n=22, AT 59.1% and AF 40.9%). A similar proportion of patients in both groups underwent repeat ablation (Group 1: 17.6% vs Group 2: 13.5%, p=0.496). Conclusions: Utilization of a CFS ablation catheter was not associated with improved clinical outcomes for stepwise catheter ablation for NPAF. The optimal strategy for NPAF ablation using a contact-force sensing catheter remains undefined

Introduction: LA ablation for persistent AF that achieves organization to atrial tachycardia (AT) or sinus rhythm (SR) predicts greater long term ablation success. However, extensive LA ablation increases the risks of recurrent AT, adverse atrial remodeling and procedural complications. Preclinical and observational studies suggest that right atrial ablation may reduce AF risk. We hypothesized that CTI ablation may reduce the extent of LA ablation required to achieve organization of persistent AF. Methods: Persistent AF patients (n=107) were randomized to two arms (CTI-first or CTI-last) in a single center, prospective, single blind study. Excluding the CTI ablation, stepwise linear LA ablation was performed in a prespecified order. The primary endpoint was the percentage of patients who organized to AT or SR. The secondary endpoint was number of steps to organization. Results: CTI ablation first versus last during AF ablation did not significantly alter the percentage of patients who organized (Table). Among those who organized, the number of steps to organization did not differ between the two arms. No significant differences were found when patients were stratified by LA size or AF duration. Conclusions: CTI ablation does not alter the extent of LA ablation needed to achieve organization of AF. The utility of right atrial ablation for persistent AF ablation remains unclear. (Table presented)