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Contact Force During Cavotricuspid Isthmus Ablation Introduction Recurrent atrial flutter following cavotricuspid isthmus (CTI) ablation remains a significant problem. The prevalence of low contact force (CF) during CTI ablation using standard tools is unknown. Our aim was to characterize the prevalence of low CF applications when experienced operators performed CTI ablation using “traditional” markers of contact blinded to CF measurements. Methods and Results Average CF (grams, g) and force-time integral (FTI) was analyzed in 458 lesions in 17 patients undergoing CTI ablation. The isthmus was divided into the annular, mid and caval segments for region-specific analysis. Despite “good” contact using traditional markers, there was significant variability in CF within each isthmus segment (e.g., annular CTI 1–57 g). A high proportion of lesions had a CF

Aims Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation of atrial fibrillation (AF). The intervenous ridge (IVR) may be incorporated into ablation strategies to achieve PVI; however, randomized trials are lacking. We performed a randomized multi-centre international study to compare the outcomes of (i) circumferential antral PVI (CPVI) alone ( minimal ) vs. (ii) CPVI with IVR ablation to achieve individual PVI ( maximal ). Methods and results Two hundred and thirty-four patients with paroxysmal AF underwent CPVI and were randomized to a minimal or maximal ablation strategy. The primary outcome of recurrent atrial arrhythmia was assessed with 7-day Holter monitoring at 6 and 12 months. PVI was achieved in all patients. Radiofrequency ablation time was longer in the maximal group (46.6 ± 14.6 vs. 41.5 ± 13.1 min; P < 0.01), with no significant differences in procedural or fluoroscopy times. At mean follow-up of 17 ± 8 months, there was no difference in freedom from AF after a single procedure between a minimal (70%) and maximal ablation strategy (62%; P = 0.25). In the minimal group, ablation was required on the IVR to achieve electrical isolation in 44%, and was associated with a significant reduction in freedom from AF (57%) compared with the minimal group without IVR ablation (80%; P < 0.01). Conclusion There was no statistically significant difference in freedom from AF between a minimal and maximal ablation strategy. Despite attempts to achieve PVI with antral ablation, IVR ablation is commonly required. Patients in whom antral isolation can be achieved without IVR ablation have higher long-term freedom from AF (the Minimax study; ACTRN12610000863033).

Patients with chronic kidney disease (CKD) undergoing hemodialysis experience a high annual mortality rate (7% per year) with 25% of all deaths due to sudden cardiac death (SCD) [(1)][1]. There has been conjecture as to the mechanism of SCD. This prospective study (Identification and

Catheter-Tissue Contact Force Determines Atrial Electrogram Characteristics Introduction Electrogram (EGM) characteristics are used to infer catheter-tissue contact. We examined if (a) atrial EGM characteristics predicted CF and (b) compared the value of CF versus other surrogates for predicting lesion efficacy. Methods and Results Twelve paroxysmal AF patients underwent pulmonary vein isolation using radiofrequency (RF) ablation facilitated by a novel CF-sensing catheter. Operators were blinded to CF. EGM amplitude, width, and morphology were measured pre- and post-RF. At each RF site, average CF, force–time integral (FTI), impedance fall, time to impedance plateau, maximum power, catheter tip temperature, and total energy delivered were recorded. An effective lesion was defined based on previously validated EGM criteria for transmural lesions. There was a moderate correlation between CF and EGM amplitude (r = 0.19) and EGM width (r = −0.22). Pre-RF, EGM amplitude, and width had modest to poor discriminative capacity for identifying preablation CF (e.g., EGM amplitude identified CF>20 g with sensitivity and specificity of 67% and 60%, respectively). Preablation CF, FTI, and total energy delivered during RF were the only independent predictors of effective lesion formation. Neither pre-RF EGM amplitude/width nor power, temperature, and impedance changes during RF predicted effective lesion formation. An average CF >16 g or FTI >404 g*s had excellent sensitivity and specificity (>80%) for identifying an effective lesion. Conclusions EGM characteristics do not reliably predict either CF before the onset of RF, nor do they predict the likelihood of an effective lesion. CF parameters were superior to power, temperature, and impedance changes during RF in predicting lesion efficacy.

Background— Catheter–tissue contact is critical for effective lesion creation. We characterized the contact force (CF) at different anatomic sites during antral pulmonary vein (PV) isolation for atrial fibrillation. Methods and Results— Two experienced operators performed PV isolation in 22 patients facilitated by a novel CF-sensing ablation catheter in a blinded fashion. Average CF and force-time integral data from 1602 lesions were analyzed. The left and right PV antra were divided into the following: carina, superior, inferior, anterior, and posterior quadrants for analysis. There was significant variability in CF within and between different PV quadrants ( P P P P P =0.19). There was no specific pattern of anatomic distribution of excess CF ( P =0.39). Conclusions— Monitoring of catheter–tissue CF during PV isolation demonstrates significant variability in CF within and between different PV antral sites. Sites of lowest CF were the carina and anterior left PVs and the carina of the right PVs. This information may be important for improving ablation efficacy and clinical outcomes during PV isolation.

Percutaneous coronary intervention (PCI) and catheter ablation are well-accepted therapeutic interventions for treatment of coronary artery disease and atrial fibrillation (AF), respectively. We sought to examine temporal trends in the provision of these services over the past decade in Australia.A retrospective review of the numbers of PCIs and AF ablations from 2000/01 to 2009/10 was performed on data from three sources: the Australian Institute of Health, Welfare and Aging (AIHW), Medicare Australia database (MA), and local records at a high volume tertiary referral centre (RMH) for AF ablation. Linear regression models were fitted comparing trends in population-adjusted procedural numbers over the 10-year period. There was a 5% per year population-adjusted increment in PCIs over 10 years from both the AIHW and MA sources, respectively (P0.001). This was similar to the growth rate of all cardiovascular procedures (AIHW: 5.1 vs. 3.8%/year, P = 0.27). Atrial fibrillation ablations showed a 30.9, 23.2, and 39.8% per year population-adjusted increment over 10 years from the AIHW, MA, and RMH sources respectively (P0.001 for all). Growth of AF ablations was significantly higher than PCIs (P0.001 for AIHW and MA sources) and all cardiovascular procedures (AIHW: 30.9 vs. 3.8%/year, P0.001).The provision of catheter-based AF ablation services in Australia has increased exponentially over the past decade. Its annual growth rate exceeded that of PCIs and all cardiovascular procedures. Given the increasing epidemic of AF, these data have critical implications for public health policy assessing the adequacy of infrastructure, training, and funding for AF ablation services.

Background— Esophageal hematoma recently has been reported as a form of esophageal injury after atrial fibrillation (AF) ablation, attributed to the use of transesophageal echocardiography (TEE). We sought to determine the incidence, clinical features, and sequelae of this form of esophageal injury. Methods and Results— This was a prospective series of 1110 AF ablation procedures performed under general anesthesia (GA) over 9 years. TEE was inserted after induction of GA to exclude left atrial appendage thrombus, define cardiac function, and guide transseptal puncture. The procedural incidence of esophageal hematoma was 0.27% (3/1110 procedures, mortality 0%). Odonyphagia, regurgitation, and hoarseness were the predominant symptoms, with an onset within 12 hours. There was absence of fever and neurological symptoms. Chest computed tomography excluded atrio-esophageal fistula and was diagnostic of esophageal hematoma localized to either the upper esophagus or extending the length of the mid and lower esophagus; endoscopy confirmed the diagnosis. Management was conservative in all cases comprising of ceasing oral intake and anticoagulation. Long term sequelae included esophageal stricture formation requiring dilatation, persistent esophageal dysmotility (mid esophageal hematoma), and vocal cord paralysis, resulting in hoarse voice (upper esophageal hematoma). Conclusions— Esophageal hematoma is a rare but important differential diagnosis for esophageal injury after TEE-guided AF ablation under GA, and can result in significant patient morbidity. Key clinical features differentiate presentation of esophageal hematoma from that of an atrio-esophageal fistula.

Aims Fluoroscopy remains a cornerstone imaging technique in contemporary electrophysiology practice. We evaluated the impact of collimation to the ‘minimal required field size’ on clinically significant parameters of radiation exposure. Methods and results Radiation dose measured by dose area product (DAP) and radiation dose rate measured by DAP per minute of fluoroscopy were determined for all 571 electrophysiology procedures performed in a single electrophysiology laboratory from January 2010 to December 2010. Data from 205 procedures performed by one interventional electrophysiologist, who instituted a practice of routinely collimating to the minimum required visual fluoroscopy field on a case-by-case basis, were compared with data from 366 procedures performed by the three other experienced interventional electrophysiologists using the laboratory who continued their existing practice of ad hoc collimation. Significant reductions in radiation exposure were seen with the practice of routine maximal collimation. The largest reductions were seen during ‘simple’ ablation procedures. Conclusion A practice of routinely collimating to the minimum required visual fluoroscopy field results in significant reductions in radiation exposure when compared with a usual approach to collimation. This may have important implications for risk of malignancy in patients and operators.

FactorsWhich Predict IndividualsWhose CoronaryArteries are “Old Before Their Time”: The Value of Computed Tomographic (Ct) Calcium Score Testing C. Ellis 1,∗, M. Legget 1, C. Edwards1, J. Ormiston1, N. Van Pelt 1, R. Gabriel 1, B. Lowe1, J. Christiansen2, H. Winch1, M. Osborne3, G. Gamble4 1 Auckland Heart Group, New Zealand 2 Waitemata Cardiology, New Zealand 3 Mercy Radiology, Mercy Hospital, Auckland, New Zealand 4 Dept of Medicine, University of Auckland, New Zealand

Objectives This study sought to determine whether post-operative neurocognitive dysfunction (POCD) occurs after ablation for atrial fibrillation (AF). Background Ablation for AF is a highly effective strategy; however, the risk of transient ischemic attack and stroke is approximately 0.5% to 1%. In addition, magnetic resonance imaging studies report a 7% to 14% prevalence of silent cerebral infarction. Whether cerebral ischemia results in POCD after ablation for AF is not well established. Methods The study included 150 patients; 60 patients undergoing ablation for paroxysmal atrial fibrillation (PAF), 30 patients undergoing ablation for persistent atrial fibrillation (PeAF), and 30 patients undergoing ablation for supraventricular tachycardia (SVT) were compared with a matched nonoperative control group of patients with AF awaiting radiofrequency ablation (n = 30). Eight neuropsychological tests were administered at baseline and at 2 days and 90 days post-operatively. The tests were administered at the same time points to the nonoperative control group. The reliable change index was used to calculate POCD. Results The prevalences of POCD at day 2 post-procedure were 28% in patients with PAF, 27% in patients with PeAF, 13% in patients with SVT, and 0% in control patients with AF (p = 0.007). At day 90, the prevalences of POCD were 13% in patients with PAF, 20% in patients with PeAF, 3% in patients with SVT, and 0% in control patients with AF (p = 0.03). When analyzing the 3 procedural groups together, 29 of 120 patients (24%) manifested POCD at day 2 and 15 of 120 patients (13%) at day 90 post-procedure (p = 0.029). On univariate analysis, increasing left atrial access time was associated with POCD at day 2 (p = 0.04) and day 90 (p = 0.03). Conclusions Ablation for AF is associated with a 13% to 20% prevalence of POCD in patients with AF at long-term follow-up. These results were seen in a patient population with predominant CHADS2 (Congestive heart failure, Hypertension, Age ≥75 years, Diabetes mellitus, previous Stroke/transient ischemic attack) scores of 0 to 1, representing the majority of patients undergoing ablation for AF. The long-term implications of these subtle changes require further study.