Intra-His bundle block with Wenckebach phenomenon.

A 66-year-old lady presented with shortness of breath and a Wenckebach atrioventricular (AV) conduction pattern on the ECG. The electrophysiologic study showed split-His potentials and intra-Hisian Wenckebach. The case highlights the interesting finding of Wenckebach conduction in the His bundle.

Age-Related Changes in the Anatomy of the Triangle of Koch: Implications for Catheter Ablation of Atrioventricular Nodal Re-entry Tachycardia.

BACKGROUND: Atrioventricular nodal re-entrant tachycardia is the most common type of paroxysmal supraventricular tachycardia. We sought to assess whether important anatomic factors, such as the location of the slow pathway, proximity to the bundle of His, and coronary sinus ostium dimensions, varied with patient age, and whether these factors had an impact on procedural duration, acute success, and complications. METHODS: Baseline demographic and procedural data were collected, and the maps were analyzed. Linear regression models were performed to evaluate the associations between age and these anatomic variations. Associations were also assessed, with age categorized as being ≥ 60 years or < 60 years. RESULTS: The slow pathway was more commonly located in a superior location relative to the coronary sinus ostium in older patients. The location of the slow pathway moved in a superior direction by 1 mm for every increase in 2 years from the mean estimate of age. Additionally the slow pathway tended to be closer to the coronary sinus ostium in older patients, and the diameter of the ostium was larger in older patients. This resulted in longer procedure time, longer ablation times, and a greater need for long sheaths for stability. CONCLUSIONS: The location of the slow pathway becomes more superior and closer to the coronary sinus ostium with increasing age. Additionally, the coronary sinus diameter increases with age. These factors result in longer ablation and procedural times in older patients.

CONTEXTE: La tachycardie par réentrée nodale auriculoventriculaire est le type le plus fréquent de tachycardie supraventriculaire paroxystique. Nous avons voulu évaluer si des facteurs anatomiques importants, tels que l'emplacement de la voie lente, la proximité du faisceau de His et les dimensions de l'orifice du sinus coronaire (ostium), variaient avec l'âge, et si ces facteurs avaient un effet sur la durée de l'intervention, le succès à court terme et les complications. MÉTHODOLOGIE: Des données sur les caractéristiques démographiques initiales et l'intervention ont été recueillies, et les cartes obtenues ont été analysées. Des modèles de régression linéaire ont servi à déterminer les corrélations entre l'âge et ces variations anatomiques. Les corrélations ont aussi été évaluées selon des catégories d'âge, soit ≥ 60 ans et < 60 ans. RÉSULTATS: La voie lente a été repérée plus souvent dans un emplacement supérieur par rapport à l'orifice du sinus coronaire chez les patients plus âgés. L'emplacement de la voie lente s'était déplacé de 1 mm vers le haut pour chaque augmentation de 2 ans de l'estimation moyenne de l'âge. Par ailleurs, chez les patients plus âgés, la voie lente était généralement plus proche de l'orifice du sinus coronaire et le diamètre de l'orifice était élargi. Ces variations se sont traduites par une augmentation du temps d'intervention et d'ablation et par un besoin accru de longues gaines pour la stabilité. CONCLUSIONS: L'emplacement de la voie lente devient plus éloigné vers le haut et plus proche de l'orifice du sinus coronaire avec le vieillissement. De plus, le diamètre du sinus coronaire augmente avec l'âge. Ces facteurs entraînent des temps d'ablation et d'intervention plus longs chez les patients plus âgés.

Challenge and Impact of Quinidine Access in Sudden Death Syndromes: A National Experience.

OBJECTIVES: This study sought to determine the nature of quinidine use and accessibility in a national network of inherited arrhythmia clinics. BACKGROUND: Quinidine is an antiarrhythmic medication that has been shown to be beneficial in select patients with Brugada syndrome, early repolarization syndrome, and idiopathic ventricular fibrillation. Because of the low prevalence of these conditions and restricted access to quinidine through a single regulatory process, quinidine use is rare in Canada. METHODS: Subjects prescribed quinidine were identified through the Hearts in Rhythm Organization that connects the network of inherited arrhythmia clinics across Canada. Cases were retrospectively reviewed for patient characteristics, indications for quinidine use, rate of recurrent ventricular arrhythmia, and issues with quinidine accessibility. RESULTS: In a population of 36 million, 46 patients are currently prescribed quinidine (0.0000013%, age 48.1 ± 16.1 years, 25 are male). Brugada syndrome, early repolarization syndrome, and idiopathic ventricular fibrillation constituted a diagnosis in 13 subjects (28%), 6 (13%), and 21 (46%), respectively. Overall, 37 subjects (81%) had cardiac arrest as an index event. After initial presentation, subjects experienced 7.47 ± 12.3 implantable cardioverter-defibrillator shocks prior to quinidine use over 34.3 ± 45.9 months, versus 0.86 ± 1.69 implantable cardioverter-defibrillator shocks in 43.8 ± 41.8 months while on quinidine (risk ratio: 8.7, p < 0.001). Twenty-two patients access quinidine through routes external to Health Canada's Special Access Program. CONCLUSIONS: Quinidine use is rare in Canada, but it is associated with a reduction in recurrent ventricular arrhythmias in patients with Brugada syndrome, early repolarization syndrome, and idiopathic ventricular fibrillation, with minimal toxicity necessitating discontinuation. Drug interruption is associated with frequent breakthrough events. Access to quinidine is important to deliver this potentially lifesaving therapy.

Clinical research: remote magnetic navigation vs. manually controlled catheter ablation of right ventricular outflow tract arrhythmias: a retrospective study.

Aims: Remote magnetic navigation (RMN) is an alternative to manual catheter control (MCC) radiofrequency ablation of right ventricular outflow tract (RVOT) arrhythmias. The data to support RMN approach is limited. We aimed to investigate the clinical and procedural outcomes in a cohort of patients undergoing RVOT premature ventricular complex/ventricular tachycardia (PVCs/VT) ablation procedures using RMN vs. MCC. Methods and results: Data was collected from two centres. Eighty-nine consecutive RVOT PVCs/VT ablation procedures were performed in 75 patients; RMN: 42 procedures and MCC: 47 procedures. CARTOXPTM or CARTO3 (Biosense Webster) was used for endocardial mapping in 19/42 (45%) in RMN group and 28/47 (60%) in MCC group; EnSiteTM NavXTM (St. Jude Medical) was used in the rest of the cohort. Stereotaxis platform (Stereotaxis Inc., St. Louis, MO, USA) was used for RMN approach. Procedural time was 113 ± 53 min in the RMN group and 115 ± 69 min in MCC (P = 0.90). Total fluoroscopic time was 10.9 ± 5.8 vs. 20.5 ± 13.8 (P < 0.05) and total ablation energy application time 7.0 ± 4.7 vs 11.9 ± 16 (P = 0.67) accordingly. There were two complications in RMN group and five in MCC (P = 0.43). Acute procedural success rate was 80% in RMN vs. 74% in MCC group (P = 0.46). After a median follow-up of 25 months (interquartile range 13-34), the success rate remained 55% in the RMN group and 53% in MCC (P = 0.96). Conclusion: Right ventricular outflow tract arrhythmia ablations were performed using half of fluoroscopic times with Stereotaxis platform RMN compared to manual approach. Acute and chronic success rates as well as complication rates were not significantly different.

Pacing Spikes All Over.

Ventricular safety pacing (VSP) is used to avoid cross talk by delivering ventricular stimulus shortly after an atrial-paced event if ventricular-sensed event occurs. Although VSP is a protective feature that exists for decades in different pacing devices, there are some reports of unfavorable outcomes of this algorithm. More so, health care providers sometimes face difficulties in interpreting and dealing with VSP strips. This case report discusses an important pacemaker algorithm and encourages further attention to possible pitfalls and hence avoids unnecessary interventions.

The gap between indicated and prescribed stroke prevention therapies in a high-risk geriatric population.

PURPOSE: The use of oral anticoagulation (OAC) in the elderly population with atrial fibrillation (AF) treated in long-term care (LTC) facilities is inconsistent. We examined the magnitude and sources of the gap between indicated and prescribed OAC in the elderly population with AF. METHODS: We retrospectively scanned the electronic medical record (EMR) and pharmacy data of 25 LTC facilities in Ontario, Canada. The diagnosis of AF was drawn from EMR. Different attributable risk factors for possible failure to prescribe OAC were examined. RESULTS: In total, 3378 active resident data were examined in the 25 LTC facilities. All the residents were ≥65 years old with mean age of 85 ± 8 years and 2449 (72%) were female. We identified 433 (13%) residents with AF with mean age 87 ± 7 years and mean CHADS2 score of 3 ± 1. Out of all residents with AF, 273 (63%) were on OAC therapy. Residents were mostly treated with warfarin (N = 114 (42%)), rivaroxaban (N = 71 (26%)) or apixaban (N = 62 (23%)) followed by dabigatran (N = 26 (10%)). Antiplatelet drugs as the only stroke prevention therapy were used in 88 (20%) residents, and 28 (6%) residents were on anticoagulation and antiplatelet drugs. Seventy-two (17%) residents were not on any antiplatelet or antithrombotic therapy. None of the potential attributable risks identified consistently correlated with the failure to prescribe indicated therapy. CONCLUSIONS: This data set suggests that 37% of eligible elderly LTC residents failed to receive recommended stroke prevention therapies.

Validation of a Novel Digital Tool in Automatic Scoring of an Online ECG Examination at an International Cardiology Meeting.

BACKGROUND: We have previously developed a novel digital tool capable of automatically recognizing correct electrocardiography (ECG) diagnoses in an online exam and demonstrated a significant improvement in diagnostic accuracy when utilizing an inductive-deductive reasoning strategy over a pattern recognition strategy. In this study, we sought to validate these findings from participants at the International Winter Arrhythmia School meeting, one of the foremost electrophysiology events in Canada. METHODS: Preregistration to the event was sent by e-mail. The exam was administered on day 1 of the conference. Results and analysis were presented the following morning to participants. RESULTS: Twenty-five attendees completed the exam, providing a total of 500 responses to be marked. The online tool accurately identified 195 of a total of 395 (49%) correct responses (49%). In total, 305 responses required secondary manual review, of which 200 were added to the correct responses pool. The overall accuracy of correct ECG diagnosis for all participants was 69% and 84% when using pattern recognition or inductive-deductive strategies, respectively. CONCLUSION: Utilization of a novel digital tool to evaluate ECG competency can be set up as a workshop at international meetings or educational events. Results can be presented during the sessions to ensure immediate feedback.

Is lower base rate detrimental to transcatheter aortic valve implantation patients requiring pacemakers?

Sudden cardiac death related to polymorphic ventricular tachycardia/ventricular fibrillation has been well reported post atrioventricular junction ablation. The practice of faster pacing rate immediately after atrioventricular junction ablation is well recognized to decrease the risk of sudden cardiac death. We propose that this practice (faster pacing rate) be implemented in patients who need permanent pacemakers secondary to transcatheter aortic valve implantation (or even surgical aortic valve interventions).

Impact of Contact Force Technology on Atrial Fibrillation Ablation: A Meta-Analysis.

BACKGROUND: Catheter-tissue contact is essential for effective lesion formation, thus there is growing usage of contact force (CF) technology in atrial fibrillation ablation. We conducted a meta-analysis to assess the impact of CF on clinical outcomes and procedural parameters in comparison to conventional catheter for atrial fibrillation ablation. METHODS AND RESULTS: An electronic search was performed using major databases. Outcomes of interest were recurrence rate, major complications, total procedure, and fluoroscopic times. Continuous variables were reported as standardized mean difference; odds ratios were reported for dichotomous variables. Eleven studies (2 randomized controlled studies and 9 cohorts) involving 1428 adult patients were identified. CF was deployed in 552 patients. The range of CF used was between 2 to 60 gram-force. The follow-up period ranged between 10 and 53 weeks. In comparing CF and conventional catheter groups, the recurrence rate was lower with CF (35.1% versus 45.5%, odds ratio 0.62 [95% CI 0.45-0.86], P=0.004). Shorter procedure and fluoroscopic times were achieved with CF (procedure time: 156 versus 173 minutes, standardized mean difference -0.85 [95% CI -1.48 to -0.21], P=0.009; fluoroscopic time: 28 versus 36 minutes, standardized mean difference -0.94 [95% CI -1.66; -0.21], P=0.01). Major complication rate was lower numerically in the CF group but not statistically significant (1.3% versus 1.9%, odds ratio 0.71 [95% CI 0.29-1.73], P=0.45). CONCLUSIONS: The use of CF technology results in significant reduction of the atrial fibrillation recurrence rate after atrial fibrillation ablation in comparison to the conventional catheter group. CF technology is able to significantly reduce procedure and fluoroscopic times without compromising complication rate.

Atrial fibrillation ablation using remote magnetic navigation and the risk of atrial-esophageal fistula: international multicenter experience.

PURPOSE: Remote magnetic navigation (RMN) has been used in various electrophysiological procedures, including atrial fibrillation (AF) ablation. Atrial-esophageal fistula (AEF) is one of most disastrous complications of AF ablation. We aimed to evaluate the incidence of AEF during AF ablation using RMN in comparison to manual ablation. METHODS: We conducted the first international survey among RMN operators for assessment of the prevalence of AEF and procedural parameters affecting the risk. Data from parallel survey of AEF among Canadian interventional electrophysiologists (CIE) using only manual catheters served as control. RESULTS: Fifteen RMN operators (who performed 3637 procedures) and 25 manual CIE operators (7016 procedures) responded to the survey. RMN operators were more experienced than CIE operators (16.3 ± 8.3 vs. 9.2 ± 5.4 practice years in electrophysiology, p = 0.007). The maximal energy output in the posterior wall was higher in the operator using RMN (33 ± 5 vs. 28.6 ± 4.9 W; p = 0.02). Other parameters including use of preprocedural images, irrigated catheter, pump flow rate, esophageal temperature monitoring, intracardiac echocardiography (ICE), and general anesthesia were similar. CIE operators administered proton-pump inhibitors postoperatively significantly more than RMN operators (76 vs. 35%, p = 0.01). AEF was reported in 5 of the 7016 patients in the control group (0.07%) but in none of the RMN group (p = 0.11). CONCLUSIONS: AEF is a rare complication and its evaluation necessitates large-scale studies. Although no AEF case with RMN was reported in this large study or previously on the literature, the rarity of this complication prevents firm conclusion about the risk.

Magnetic resonance estimates of the extent and heterogeneity of scar tissue in ICD patients with ischemic cardiomyopathy predict ventricular arrhythmia.

BACKGROUND: The majority of patients receiving implantable cardioverter-defibrillator (ICD) implantation under current guidelines never develop sustained ventricular arrhythmia; therefore, better markers of risk for sustained ventricular tachycardia and/or ventricular fibrillation are needed. OBJECTIVE: The purpose of this study was to identify cardiac magnetic resonance arrhythmic risk predictors of ischemic cardiomyopathy before ICD implantation. METHODS: Forty-three subjects (mean age, 64.5 ± 11.9 years) with previous myocardial infarction who were referred for ICD implantation were evaluated by cardiac magnetic resonance imaging (MRI). The MRI protocol included left ventricular functional parameter assessment using steady-state free precession and late gadolinium enhancement MRI using inversion recovery fast gradient echo. Left ventricular functional parameters were measured using cardiac magnetic resonance software. Subjects were followed up for 6-46 months, and the events of appropriate ICD treatments (shocks and antitachycardia pacing) were recorded. RESULTS: Twenty-eight patients experienced 46 spontaneous episodes during a median follow-up duration of 30 months. The total myocardial infarct (MI) size (18.05 ± 11.44 g vs 38.83 ± 19.87 g; P = .0006), MI core (11.63 ± 7.14 g vs 24.12 ± 12.73 g; P = .0002), and infarct gray zone (6.43 ± 4.64 g vs 14.71 ± 7.65 g; P = .0004) were significantly larger in subjects who received appropriate ICD therapy than in those who did not experience an episode of ventricular tachycardia and/or ventricular fibrillation. Multivariate regression analyses for the infarct gray zone and MI core adjusted for New York Heart Association class, diabetes, and etiology (primary or secondary prevention) revealed that the gray zone and MI core were predictors of appropriate ICD therapies (P = .0018 and P = .007, respectively). CONCLUSION: The extent of MI scar may predict which patients would benefit most from ICD implantation.

Empiric slow pathway ablation in non-inducible supraventricular tachycardia.

BACKGROUND: The data supporting the practice of empiric slow pathway ablation (ESPA) in patients with documented supraventricular tachycardia (SVT) who are non-inducible at electrophysiology study (EPS) is limited. The aim of this study is to assess the efficacy of ESPA in adults. METHODS: A multi-center cohort study of patients who had ESPA between January 2008 and October 2013 was performed. Patients were identified by screening sequential SVT ablation procedures. RESULTS: Forty-three (5%) out of 859 SVT ablation procedures were identified as ESPA. The median age was 53 (IQR: 24) years; 63% were female. All patients had pre-EPS documentation of SVT (either strip or ECG). In 23 (53.5%) cases, pre-EPS ECG showed short RP tachycardia. Thirty-two (74.4%) patients had dual atrioventricular nodal physiology (DAVNP) plus echo beats. Junctional rhythm (JR) as procedural endpoint was noted in 39 (90.7%) patients. In 18 (41.9%) patients, the abolishment of DAVNP was achieved. No complications were encountered. A median follow-up of 17 months (range: 6 to 31 months) revealed 83.7% (36 of 43) success rate, defined as the absence of pre-procedural symptoms and any documented sustained arrhythmia. As compared to patients with recurrence (n=7), patients with no recurrence (n=36) had significantly higher prevalence of clinical short RP tachycardia (61.1% vs. 14.3%, p=0.038), and EPS finding of DAVNP plus echo beats (80.6% vs. 42.9%, p=0.034). CONCLUSIONS: ESPA is a reasonable approach in patients with documented SVT, in particular in short RP tachycardia, who are not inducible at EPS. Larger studies are required to assess this practice.

The prevalence and risk factors for atrioesophageal fistula after percutaneous radiofrequency catheter ablation for atrial fibrillation: the Canadian experience.

PURPOSE: Atrioesophageal fistula (AEF) is an infrequent complication of radiofrequency (RF) ablation for atrial fibrillation (AF). The aim of this study was to determine the prevalence and operator-dependent factors associated with AEF using a nationwide survey of electrophysiologists (EP). METHODS: Thirty-eight EPs performing AF ablation between 2008 and 2012 were invited to complete a web-based questionnaire assessing the prevalence and factors associated with AEF. RESULTS: Responses were obtained from 25 EPs (68 %) accounting for 7,016 AF ablations. Five cases of proven AEF (0.07 %) were reported. Operators who reported AEF [AEF (+)] more often used general anesthesia (GA) [90 % AEF (+) vs. 44 % AEF (-), p = 0.046]. AEF (+) operators were also more likely to be users of the non-brushing technique in the posterior wall of the LA [5 (100 %) AEF (+) vs. 5 (25 %) AEF (-), p = 0.005]. The combined usage of GA and non-brushing technique during LA posterior wall ablation had a strong association with AEF (+) operators [4 (80 %) AEF (+) vs. 2 (10 %) AEF (-), p = 0.002]. There was a trend towards higher maximal RF energy setting in the posterior wall [47.4 + 7.6 AEF (+) vs. 40.2 + 8 AEF (-), p = 0.09]. Other procedure parameters were similar. CONCLUSIONS: The reported prevalence of AEF among Canadian AF ablators is 0.07 %. AEF was associated with high mortality. The use of GA and non-brushing movements during posterior wall ablation were two factors associated with AEF.

Robotically assisted ablation of atrial fibrillation: a systematic review and meta-analysis.

BACKGROUND: Robotic systems are becoming increasingly common in complex ablation procedures. We conducted systematic review and meta-analysis on the procedural outcomes of Magnetic Navigation System (MNS) in comparison to conventional catheter navigation for atrial fibrillation (AF) ablation. METHODS: An electronic search was performed using multiple databases between 2002 & 2012. Outcomes were: acute and long-term success, complications, total procedure, ablation and fluoroscopic times. RESULTS: Fifteen studies (11 nonrandomized controlled studies & 4 case series) involving 1647 adult patients were identified. In comparison between MNS and conventional groups, a tendency towards higher acute success was noted with conventional group but with similar long-term freedom from AF (95% vs. 97%, odds ratio (OR) 0.25 (95% confidence interval [CI] 0.06; 1.04, p=0.057); 73% vs. 75%, OR 0.92 (95% CI 0.69; 1.24, p=0.59), respectively). A significantly shorter fluoroscopic time was achieved with MNS (57 vs. 86 min, standardized difference in means (SDM) -0.90 (95% CI -1.68; -0.12, p=0.024)). Longer total procedure and ablation times were noted with MNS (286 vs. 228 min, SDM 0.7 (95% CI 0.28; 1.12, p=0.001); 67 vs. 47 min, SDM 0.79 (95% CI 0.18; 1.4, p=0.012), respectively). Overall complication rate was similar (2% vs. 5%, OR 0.48 (95% CI 0.18; 1.26, p=0.135)), however rate of significant pericardial complication defined either as tamponade or effusion requiring intervention/hospitalization was significantly lower in MNS (0.3% vs. 2.5%, p=0.005). CONCLUSIONS: Our results suggest that MNS has similar rates of success and possibly superior safety outcomes when compared to conventional manual catheter ablation for AF.

Safety and efficacy of dabigatran compared with warfarin for patients undergoing radiofrequency catheter ablation of atrial fibrillation: a meta-analysis.

BACKGROUND: The safety and efficacy of dabigatran in the periprocedural period for patients undergoing atrial fibrillation ablation is not well established. We conducted a meta-analysis of the periprocedural use of dabigatran vs warfarin (with or without heparin bridging). METHODS: A literature search was performed using multiple databases. Outcomes were (1) major bleeding; (2) minor bleeding; and (3) thromboembolic events. Odds ratios (ORs) were reported for dichotomous variables. RESULTS: Eleven controlled studies (9 cohorts, 1 randomized controlled trial and 1 case-control study; 3841 patients) were identified. Dabigatran was used in 1463 patients, uninterrupted in 223 and held up to 36 hours in the remainder. No significant differences were noted in major bleeding rates between dabigatran and warfarin groups (1.9% vs. 1.6%; OR, 1.04 [95% confidence interval (CI), 0.51-2.13]; P = 0.92). Cardiac tamponade was observed in 1.4% in dabigatran vs 1.1% in warfarin groups (OR, 1.1; 95% CI, 0.55-2.11; P = 0.82). Similar rates for dabigatran vs. warfarin were reported for minor bleeding (3.8% vs. 4.5%; OR, 0.85; 95% CI, 0.58-1.25; P = 0.40), hematoma (2% vs. 2.7%; OR, 0.67; 95% CI, 0.41-1.08; P = 0.1), and thromboembolic events (0.6% vs. 0.1%; OR, 2.51; 95% CI, 0.78-8.11; P = 0.12). CONCLUSIONS: This meta-analysis suggests that dabigatran and warfarin have similar safety and efficacy overall for periprocedural anticoagulation in patients undergoing radiofrequency atrial fibrillation ablation. Signals were seen favouring dabigatran (for hematomas) and warfarin (for thromboembolic events), but neither was statistically significant because of low event rates. More high-quality data are required to definitively compare the 2 strategies.

Remote magnetic navigation for catheter ablation of atrioventricular nodal reentrant tachycardia: a systematic review and meta-analysis.

Catheter ablation has become a well-established, first-line therapy for atrioventricular nodal reentrant tachycardia (AVNRT), the most common reentry supraventricular tachycardia in humans. Robotic systems are becoming increasingly common in both complex and simple ablation procedures with presumed potential improvements in procedural efficacy and safety. The authors of this article conducted a systematic review and meta-analysis on the effectiveness and safety of the magnetic navigation system (MNS) in comparison with conventional catheter navigation for AVNRT ablation. An electronic search was performed using Cochrane Central database, Medline, Embase and Web of Knowledge between 2002 and 2012. References were searched manually. Outcomes of interest were: acute and long-term success, complications, total procedure, ablation and fluoroscopic times. Continuous variables were reported as standardized difference in means (SDM); odds ratios (OR) were reported for dichotomous variables. Thirteen studies (seven of which were nonrandomized controlled, four were case series and two were randomized controlled studies) involving 679 adult patients were identified. Twelve studies were based on a single center and one study was multicentral. MNS was deployed in 339 patients. The follow-up period ranged between 75 and 180 days. Acute success and long-term freedom from arrhythmia were not significantly different between MNS and control groups (98 vs 98%, OR: 0.94 [95% CI: 0.21-4.1] and 97 vs 96%, OR: 1.18 [95% CI: 0.35-4.0], respectively). A shorter fluoroscopic time was achieved with MNS; however, this did not reach statistical significance (15 vs 19 min, SDM: -0.26 [95% CI: -0.64-0.12]). Longer total procedure but similar ablation times were noted with MNS (160 vs 148 min, SDM: 3.48 [95% CI: 0.75-6.21] and 4 vs 6 min, SDM: -0.83 [95% CI: -2.19-0.53], respectively). The overall complication rate was similar between both groups (2.7 vs 1.0%, OR: 1.28 [95% CI: 0.33-4.96]). Our data suggest that the usage of MNS results in similar rates of success and complications when compared with conventional manual catheter ablation for AVNRT. MNS had a trend for reduced fluoroscopic time. Longer total procedure time was observed with MNS while the actual ablation time remained similar. Prospective randomized trials will be needed to better evaluate the relative role of MNS for catheter ablation of AVNRT.

Three-dimensional localization versus fluoroscopically only guided ablations: a meta-analysis.

OBJECTIVES: Data regarding efficacy and safety of three-dimensional localization systems (3D) are limited. We performed a meta-analysis of randomized trials comparing combined fluoroscopy- and 3D guided to fluoroscopically-only guided procedures. DESIGN: A systematic search was performed using multiple databases between 1990 and 2010. Outcomes were acute and long-term success, ablation, procedure and fluoroscopic times, radiation dose (RD), and complications. RESULTS: Thirteen studies involving 1292 patients were identified. 3D were tested against fluoroscopic guidance in 666 patients for supraventricular tachycardia (SVT), atrial flutter (AFL), atrial fibrillation (AF), and ventricular tachycardia (VT). Acute and long-term freedom from arrhythmia was not significantly different between 3D and control for AFL (acute success, 97% vs. 93%, p = 0.57; chronic success, 93% vs. 96%, p = 0.90) or for SVT (acute success, 94% vs. 100%, p = 0.36; chronic success, 88% vs. 88%, p = 0.80). A shorter fluoroscopic time was achieved with 3D in AFL (p < 0.001) and in SVT (p = 0.002). RD was significantly less for both AFL (p = 0.002) and SVT (p = 0.01). Ablation and procedure time and complications were not statistically different. CONCLUSIONS: Success, procedure time, and complications were similar between fluoroscopy- and 3D-guided ablations. Fluoroscopic time and RD were significantly reduced for ablation of AFL and SVT with 3D.

Approaches to empiric ablation of slow pathway: results from the Canadian EP web survey.

AIM: Dual atrioventricular nodal physiology (DAVNP) is a frequent finding in patients with suspected or documented supraventricular tachycardia (SVT). Empiric slow pathway ablation (ESPA) is sometimes performed in patients with DAVNP without inducible SVT at the time of electrophysiological study. Evidence to guide this practice in the adult population is limited. This study was aimed to assess the practice of ESPA by adult electrophysiologists in Canada. METHODS: All Canadian interventional electrophysiologists (n = 81) were invited to complete a web-based questionnaire assessing their practice of ESPA in patients with suspected and documented SVT. Operator experience, reimbursement models, diagnostic, and treatment decisions regarding ESPA were assessed with case scenarios. RESULTS: Forty-one responses (50 %) were obtained. Ninety-five percent of the responders stated that the evidence for ESPA is lacking or limited. Responders were more likely to perform ESPA in the setting of non-inducible SVT when there was documentation of the clinical arrhythmia (64 vs. 31 % (p = 0.017)). The threshold to perform ESPA was highly variable. Longer time in practice (r = 0.38, p = 0.017) and less perceived complications with ESPA (r = 0.31, p = 0.05) were correlated with the practice of ESPA, whereas length of ablation waiting lists (r = -0.15, p = 0.38), number of procedures performed per day (r = 0.11, p = 0.51) and type of reimbursement (p = 0.24) were not associated with the practice of ESPA. The perceived complication rate with ESPA was <1 %. CONCLUSION: Variability in the practice of ESPA in cases of non-inducible SVT exists. Documentation of the clinical arrhythmia, operator experience, and perceived low complication rates positively influence this practice.

Correspondence between simple 3-D MRI-based computer models and in-vivo EP measurements in swine with chronic infarctions.

The aim of this paper was to compare several in-vivo electrophysiological (EP) characteristics measured in a swine model of chronic infarct, with those predicted by simple 3-D MRI-based computer models built from ex-vivo scans (voxel size <1 mm(3)). Specifically, we recorded electroanatomical voltage maps (EAVM) in six animals, and ECG waves during induction of arrhythmia in two of these cases. The infarct heterogeneities (dense scar and border zone) as well as fiber directions were estimated using diffusion weighted DW-MRI. We found a good correspondence (r = 0.9) between scar areas delineated on the EAVM and MRI maps. For theoretical predictions, we used a simple two-variable macroscopic model and computed the propagation of action potential after application of a train of stimuli, with location and timing replicating the stimulation protocol used in the in-vivo EP study. Simulation results are exemplified for two hearts: one with noninducible ventricular tachycardia (VT), and another with a macroreentrant VT (for the latter, the average predicted VT cycle length was 273 ms, compared to a recorded VT of 250 ms).