KCND3 potassium channel gene variant confers susceptibility to electrocardiographic early repolarization pattern.

BACKGROUNDThe presence of an early repolarization pattern (ERP) on the surface ECG is associated with risk of ventricular fibrillation and sudden cardiac death. Family studies have shown that ERP is a highly heritable trait, but molecular genetic determinants are unknown.METHODSTo identify genetic susceptibility loci for ERP, we performed a GWAS and meta-analysis in 2,181 cases and 23,641 controls of European ancestry.RESULTSWe identified a genome-wide significant (P < 5 × 10-8) locus in the potassium voltage-gated channel subfamily D member 3 (KCND3) gene that was successfully replicated in additional 1,124 cases and 12,510 controls. A subsequent joint meta-analysis of the discovery and replication cohorts identified rs1545300 as the lead SNP at the KCND3 locus (OR 0.82 per minor T allele, P = 7.7 × 10-12) but did not reveal additional loci. Colocalization analyses indicate causal effects of KCND3 gene expression levels on ERP in both cardiac left ventricle and tibial artery.CONCLUSIONSIn this study, we identified for the first time to our knowledge a genome-wide significant association of a genetic variant with ERP. Our findings of a locus in the KCND3 gene provide insights not only into the genetic determinants but also into the pathophysiological mechanism of ERP, discovering a promising candidate for functional studies.FUNDINGThis project was funded by the German Center for Cardiovascular Research (DZHK Shared Expertise SE081 - STATS). For detailed funding information per study, see the Supplemental Acknowledgments.

Two in one is better than one plus one: comparison of adverse events between combining electrophysiological examination and coronary angiography versus performing them consecutively.

PURPOSE: In some patients, both an electrophysiological examination (EPS) and a coronary angiography (CA) are necessary. It might be preferable to choose a combined approach of EPS and CA versus performing them consecutively. The purpose of this study is to evaluate the type and rate of adverse events between both approaches. METHODS: Patients were eligible if they underwent a CA and an EPS in a combined approach or in a time interval of at most 2 months. In all patients, clinical adverse events were recorded. RESULTS: A total of 1184 patients were included. CA and EPS were performed in a combined procedure (comb) in 492 patients, whereas they were performed consecutively in 692 patients (cons). The acute major complication rate was 0.67%, showing no differences between both groups. In the comb 6.9% and in the cons 6.6% of vascular complications were observed (p = 0.20). The rates of AV fistula and hematoma needing transfusion showed a significantly higher rate in the cons group (p = 0.018 and p = 0.045, respectively). In a multivariate logistic regression analysis, age was a significant predictor for groin complications. After propensity matching, AV fistula occurred significantly more often in the cons group (p = 0.002). CONCLUSION: Overall, serious adverse events were rare and there were no differences between the combined approach of EPS and CA and the consecutive approach; however, the occurrence of AV fistula and groin hematoma needing transfusion occurred significantly less in the combined procedure group. Therefore, a combined approach is preferable to a consecutive one.

Ablation of Complex Fractionated Electrograms With or Without ADditional LINEar Lesions for Persistent Atrial Fibrillation (The ADLINE Trial).

BACKGROUND: For persistent atrial fibrillation (AF) ablation, different strategies including complex fractionated atrial electrograms (CFAE) ablation and linear lesions (LL) have been used in addition to pulmonary vein isolation (PVI). However, it is still a matter of debate if extended substrate modification improves long-term outcome. The aim of this study was to determine the benefit of LL in addition to PVI and CFAE ablation regarding freedom from arrhythmia recurrence in patients with persistent AF. METHODS: The study was a prospective randomized trial including 90 patients with persistent and longstanding persistent AF. All patients underwent PVI and CFAE ablation. If AF did not terminate to atrial tachycardia (AT) or sinus rhythm, patients were randomized to direct current cardioversion (Group 1; n = 45) or LL (Group 2; n = 45). Primary endpoint was freedom from any atrial arrhythmia off antiarrhythmic drugs at 12 months. (NCT02059369) RESULTS: Baseline characteristics were similar between the two groups with more than half of the patients having structural heart disease. The primary endpoint was reached in 37% in Group 1 (G1) and 16% in Group 2 (G2; P = 0.03). After a total number of 1.4 ± 0.5 (G1) versus 1.7 ± 0.4 (G2; P = 0.01) procedures, freedom from any arrhythmia was reached in 54% in G1 and 65% in G2 (P = 0.35). CONCLUSION: In persistent AF ablation, LL in addition to PVI and CFAE show a significantly lower success rate after a single procedure compared to PVI and CFAE. Following LL, significantly more patients needed a reablation to reach a similar success rate during a 12-month follow-up.

Fiberoptic Contact-Force Sensing Electrophysiological Catheters: How Precise Is the Technology?

BACKGROUND: Contact-force (CF) sensing catheters are increasingly used in electrophysiological procedures due to their efficacy and safety profile. As data about the accuracy of fiberoptic CF technology are scarce, we sought to quantify it using in vitro experiments. METHODS AND RESULTS: A force sensor was built with a flexible membrane to allow exact reference force measurements for each set of experiments. A TactiCath Quartz (TCQ) ablation catheter was brought in contact with the force sensor membrane in order to compare the TCQ force measurements to sensor reference force measurements. Measurements were performed at different tip angles (0°/perpendicular contact, 45°, 90°/parallel contact), with fluid irrigation, different degrees of catheter deflection, and using a sheath. The accuracy of the TCQ force measurements was 0.9 ± 0.9 g (0°), 0.8 ± 0.8 g (45°) and 1.2 ± 1.3 g (90°), 0.8 ± 0.7 g (irrigation), 0.8 ± 0.8 g (deflection), and 0.8 ± 0.9 g (sheath); this was not significantly different among all experimental conditions. The precision was ≤3.8%. CONCLUSION: CF measurements using a fiberoptic sensing technology show a high level of accuracy and precision, without being significantly influenced by tip angle, fluid irrigation, catheter deflection or use of a sheath.

Impact of acute atrial fibrillation termination and prolongation of atrial fibrillation cycle length on the outcome of ablation of persistent atrial fibrillation: A substudy of the STAR AF II trial.

BACKGROUND: Controversy exists about the impact of acute atrial fibrillation (AF) termination and prolongation of atrial fibrillation cycle length (AFCL) during ablation on long-term procedural outcome. OBJECTIVE: The purpose of this study was to analyze the influence of AF termination and AFCL prolongation on freedom from AF in patients from the STAR AF II (Substrate and Trigger Ablation for Reduction of Atrial Fibrillation Trial-Part II) trial. METHODS: Acute changes in AFCL and AF termination were collected during the index procedure of the STAR AF II trial and compared to recurrence of AF at 18 months. Recurrence was assessed by ECG, Holter (3, 6, 9, 12, 18 months), and weekly transtelephonic ECG monitoring for 18 months. RESULTS: AF terminated in 8% of the pulmonary vein isolation (PVI) arm, 45% in the PVI+complex electrogram arm, and 22% of the PVI+linear ablation arm (P <.001), but freedom from AF did not differ among the 3 groups (P = .15). Freedom from AF was significantly higher in patients who presented to the laboratory in sinus rhythm (SR) compared to those without AF termination (63% vs 44%, P = .007). Patients with AF termination had an intermediate outcome (53%) that was not significantly different from those in SR (P = .84) or those who did not terminate (P = .08). AF termination was a univariable predictor of success (P = .007), but by multivariable analysis, presence of early SR was the strongest predictor of success (hazard ratio 0.67, P = .004). Prolongation of AFCL was not predictive of 18-month freedom from AF. CONCLUSION: Acute AF termination and prolongation in AFCL did not consistently predict 18-month freedom from AF. Presence of SR before or early during the ablation was the strongest predictor of better outcome.

Electromagnetic interference in implantable cardioverter defibrillators: present but rare.

PURPOSE: Electromagnetic interference (EMI) with implantable cardioverter defibrillators (ICDs) can cause oversensing and subsequently inappropriate ICD therapies. We retrospectively investigated the current incidence and clinical relevance of oversensing related EMI in a large cohort of ICD patients. METHODS: From January 2005 to April 2013, all ICD interrogations performed at our institution were analyzed for the occurrence of oversensing related EMI. EMI episodes were classified as clinically significant, potentially significant or of minor significance. To identify risk factors for EMI, we also analyzed different lead models in our cohort (integrated vs true bipolar leads). RESULTS: Data of 2940 ICD patients (mean age 63 ± 16 years, 2322 male patients, 7772 patient-years) were retrospectively analyzed for the occurrence of EMI. During the observation period, a total of 145 (hospital environment n = 97, non-hospital environment n = 48) episodes occurred and resulted in an overall EMI incidence, i.e. event rate, of 1.87 % per patient per year. Focusing on clinically significant or potentially significant episodes, the EMI incidence was 0.27 % per patient per year. Cox proportional hazards regression analysis did not reveal a statistically significant higher hazard of oversensing for patients with integrated bipolar leads compared to patients with true bipolar leads (HR = 2.21; 95 % CI 0.90-5.39; p = 0.083). CONCLUSIONS: Our data demonstrate that EMI continues to occur in everyday life. Patients should be well informed about the potential sources and risks of EMI but they need not be overly concerned since the risk of EMI-especially in a non-hospital environment-is low.

Evaluation of a new very low dose imaging protocol: feasibility and impact on X-ray dose levels in electrophysiology procedures.

AIMS: This study presents and evaluates the impact of a new lowest-dose fluoroscopy protocol (Siemens AG), especially designed for electrophysiology (EP) procedures, on X-ray dose levels. METHODS AND RESULTS: From October 2014 to March 2015, 140 patients underwent an EP study on an Artis zee angiography system. The standard low-dose protocol was operated at 23 nGy (fluoroscopy) and at 120 nGy (cine-loop), the new lowest-dose protocol was operated at 8 nGy (fluoroscopy) and at 36 nGy (cine-loop). Procedural data, X-ray times, and doses were analysed in 100 complex left atrial and in 40 standard EP procedures. The resulting dose-area products were 877.9 ± 624.7 µGym² (n = 50 complex procedures, standard low dose), 199 ± 159.6 µGym² (n = 50 complex procedures, lowest dose), 387.7 ± 36.0 µGym² (n = 20 standard procedures, standard low dose), and 90.7 ± 62.3 µGym² (n = 20 standard procedures, lowest dose), P < 0.01. In the low-dose and lowest-dose groups, procedure times were 132.6 ± 35.7 vs. 126.7 ± 34.7 min (P = 0.40, complex procedures) and 72.3 ± 20.9 vs. 85.2 ± 44.1 min (P = 0.24, standard procedures), radiofrequency (RF) times were 53.8 ± 26.1 vs. 50.4 ± 29.4 min (P = 0.54, complex procedures) and 10.1 ± 9.9 vs. 12.2 ± 14.7 min (P = 0.60, standard procedures). One complication occurred in the standard low-dose and lowest-dose groups (P = 1.0). CONCLUSION: The new lowest-dose imaging protocol reduces X-ray dose levels by 77% compared with the currently available standard low-dose protocol. From an operator standpoint, lowest X-ray dose levels create a different, reduced image quality. The new image quality did not significantly affect procedure or RF times and did not result in higher complication rates. Regarding radiological protection, operating at lowest-dose settings should become standard in EP procedures.

Dissociated pulmonary vein activity after pulmonary vein isolation for paroxysmal atrial fibrillation: a predictor for recurrence?

BACKGROUND: The role of dissociated pulmonary vein (DPV) activity after pulmonary vein isolation (PVI) is still poorly defined. We evaluated electrophysiological features and clinical impact on long-term outcome of DPV activity. METHODS: A total of 243 patients (mean age 63 ± 11 years; 63% males) undergoing PVI for paroxysmal atrial fibrillation (AF) were included. DPV activity was defined as a residual low frequency irregular PV rhythm. Patients were divided into Group 1 (presence of DPV activity; n = 65) or Group 2 (absence of DPV activity; n = 178). RESULTS: Of 936 isolated PVs, 112 PVs (12%) showed DPV activity. DPV activity was observed more frequently in PVs identified as AF triggers (P = 0.026). During follow-up (mean 12 ± 7 months), 15 of 65 patients of Group 1 (23%) and 57 of 178 patients of Group 2 (32%) had an arrhythmia recurrence (P = 0.23). At linear regression analysis, no independent predictor for clinical recurrence was identified. During the repeat ablation, 62 of 72 patients (86%) showed a recovered PV conduction without difference between the 2 groups. Clinically, all patients of Group 1 with PV reconnection (n = 13/15) had a recurrence of paroxysmal AF. In Group 2, 5 of 52 patients with reconnected PV developed non-PV related arrhythmias. CONCLUSION: DPV activity occurred in 12% of PVs after PVI and was observed more frequently in PVs identified as AF triggers. DPV activity was not predictive for AF recurrence during follow-up. PV-left atrium reconnection involving PVs with DPV activity leads to AF.

A prospective randomized study comparing isolation of the arrhythmogenic vein versus all veins in paroxysmal atrial fibrillation.

BACKGROUND: Ablation procedures in patients with paroxysmal atrial fibrillation (PAF) includes isolation of all pulmonary veins (PVs). We hypothesized that an approach using an algorithm to detect arrhythmogenic PVs (aPVs) might lead to shorter procedure duration (PD) and fewer proarrhythmic effects (PE). HYPOTHESIS: Isolation of the aPVs only leads to a reduced PD, reduced PEs, and fewer adverse events, with a success rate comparable to the standard all-PV approach. METHODS: In this prospective trial, 207 patients with PAF were randomized to undergo isolation of the aPV (AG group, n = 105) or isolation of all PVs (VG group, n = 102). The aPV was identified by atrial fibrillation (AF) induction, focal discharge, or short local PV decremental conduction during PV pacing. Patients were followed with repetitive 7-day Holter electrocardiograms (ECGs) after 3, 6, and 12 months in our arrhythmia clinic. RESULTS: In 97% of patients, at least 1 aPV was identified (mean, 2.1). PD did not differ significantly (152.3 ± 57.1 minutes vs 162 ± 68 minutes, P = 0.27) between the groups, but the number of radiofrequency (RF) applications and fluoroscopy time (FT) and dose were significantly lower in the AG group than in the VG group. The occurrence of PE (new-onset atrial tachycardia) and adverse events (AE) did not differ between the 2 groups (P = 0.1). Sinus rhythm off antiarrhythmic medication (documented on 7-day Holter ECGs) 12 months after a single procedure was achieved in 53% in the AG group and 59% in the VG group (P = 0.51). CONCLUSIONS: Isolation of the aPVs detected by a straightforward algorithm leads to similar success rates compared to a standard all-PV approach with regard to PD, AE, or PE and is associated with less RF and a shorter FT.

Importance of sinus rhythm as endpoint of persistent atrial fibrillation ablation.

BACKGROUND: The endpoint of persistent atrial fibrillation (AF) ablation is still a matter of debate. The purpose of this study was to evaluate if sinus rhythm (SR) as endpoint of persistent AF ablation has a better long-term outcome compared to atrial tachycardia (AT) or AF at the end of the procedure. METHODS AND RESULTS: Between 2008 and 2011, 191 consecutive patients undergoing de novo catheter ablation for symptomatic persistent and long-standing persistent AF using a sequential ablation approach (including pulmonary vein isolation, ablation of complex fractionated electrograms and linear lesions) were included in the study. According to the result at the end of ablation procedure, patients were classified into 3 groups: patients with termination of AF into SR (Group 1, n = 62), patients with AT undergoing cardioversion (CV) (Group 2, n = 47), or patients with AF undergoing CV (Group 3, n = 82). The primary endpoint was freedom from any atrial tachyarrhythmia off antiarrhythmic drugs at 12 months. At 12 months, estimated proportions of patients free from any arrhythmia recurrence were 42% for Group 1, 13% for Group 2, and 25% for Group 3 (P = 0.002). In a Cox regression analysis only termination into SR was associated with a lower risk of arrhythmia recurrence (HR: 0.62; P = 0.04). CONCLUSION: If SR is achieved as endpoint of persistent and long-standing persistent AF ablation using a sequential ablation approach it is associated with the highest long-term single procedure success rate compared to AT or AF at the end of the procedure.

Complex fractionated atrial electrogram or linear ablation in patients with persistent atrial fibrillation--a prospective randomized study.

BACKGROUND: Catheter ablation of complex fractionated atrial electrograms (CFAE) for persistent atrial fibrillation (AF) is a promising treatment strategy. We tested the hypothesis that CFAE ablation is superior to linear ablation in patients with persistent or long-standing persistent AF. METHODS: In this study, 116 patients with persistent AF were randomly assigned to undergo circumferential PVI plus additional lines (linear ablation group; 59 patients) or CFAE ablation plus ostial pulmonary vein isolation (PVI) (spot ablation group; 57 patients). Primary endpoint was freedom from atrial tachyarrhythmia after a single ablation procedure (clinical and repeat 7-day Holter), 12 months after ablation without antiarrhythmic medication. RESULTS: The primary endpoint was reached in 22 of 59 (37%) patients of the linear ablation group and in 22 of 57 (39%) patients of the spot ablation group (P = 0.9). Freedom from atrial tachyarrhythmias, including reablations, was achieved in 54% of patients (linear ablation group) versus 56% of patients (spot ablation group; P = 0.8). The incidence of recurrent persistent AF was higher after linear ablation than after spot ablation (21/37 vs 11/35 patients; P = 0.03); atrial tachycardia (AT) was seen more often after spot ablation (10/35 vs 4/37 patients; P = 0.03). CONCLUSION: In patients with persistent AF, CFAE ablation plus PVI reaches the same results as circumferential PVI plus lines, in terms of freedom from symptomatic atrial tachyarrhythmias within the first year after a single ablation procedure. Arrhythmia recurrences in patients after spot ablation were caused more often by AT, whereas recurrent persistent AF was more prevalent after the linear ablation approach.

Mapping of atrial tachycardia by remote magnetic navigation in postoperative patients with congenital heart disease.

OBJECTIVES: The purpose of this study was to investigate if remote magnetic navigation (RMN) offers a reduction of fluoroscopy time when used for atrial tachycardia (AT) mapping in a spectrum of patients with congenital heart disease (CHD) after "simple" or "complex" atrial surgery. BACKGROUND: Data about AT mapping using RMN in larger populations of patients with CHD are scarce. METHODS: RMN in combination with electroanatomic mapping was used for AT mapping in 22 patients. According to anatomic complexity, patients were classified into 3 groups: Group 1: patients after minor atrial surgery (n = 7); Group 2: patients after the Fontan operation (n = 9); and group 3: patients after the Senning/Mustard operation (n = 6). RESULTS: Atrial mapping with a nonirrigated tip RMN catheter was completed successfully in all patients. In Group 1 no significant reduction in fluoroscopy time was noticed over time (mean fluoroscopy time 7.9 minutes). In the 15 patients of group 2 and group 3 with complex CHD, the fluoroscopy time for mapping in the last 9 patients (6.4 +/- 2.8 minutes) was significantly shorter than in the first 6 patients (29.7 +/- 10.5 minutes, P < 0.0001). Acutely successful ablation was achieved in 21 of 22 patients (97%) using the RMN catheter (n = 3) or a conventional catheter (n = 18) without procedural complications. CONCLUSIONS: RMN for AT mapping in patients with complex atrial anatomy leads to a significant reduction of fluoroscopy time.

Systemic inflammatory changes after pulmonary vein radiofrequency ablation do not alter stem cell mobilization.

AIMS: Aim of this study was to investigate the number of circulating progenitor cells, systemic inflammatory mediators, and myocardial necrosis in patients with paroxysmal atrial fibrillation (AF) undergoing pulmonary vein (PV) isolation by radiofrequency (RF) ablation. Radiofrequency ablation generates a localized myocardial necrosis that might result in a release of inflammatory mediators enhancing progenitor cell mobilization and improving tissue repair. METHODS AND RESULTS: Blood samples were collected in patients with paroxysmal AF before and after PV isolation. Interleukin (IL)-6, IL-1beta, TNF-alpha, IL-8, IL-10, and IL-12, and stromal derived factor (SDF)-1 were measured by immunoassay. CD34+CD133+, CD117+, and endothelial progenitor cells (EPCs) were analysed by flow cytometry and culture assay. After ablation procedure, a rise in creatine kinase and troponin T levels indicated myocardial necrosis. Leukocyte counts and C-reactive protein and IL-6 levels increased significantly. Myocardial necrosis and inflammatory response correlated with an increase in IL-6 (P = 0.007). In contrast, SDF-1 levels decreased after RF ablation (P = 0.004). Yet, no significant changes were observed in IL-1beta, TNF-alpha, IL-8, IL 10, and IL-12 plasma levels or in the number of circulating CD34+CD133+ and CD117+ progenitor cells, whereas EPCs decreased by trend. CONCLUSION: Although PV isolation by RF ablation in patients with paroxysmal AF induces a systemic inflammatory response associated with myocardial necrosis, no alterations in circulating progenitor cells were observed. Thus, isolated myocardial necrosis may not be sufficient to account for progenitor cell mobilization.

Acute effects and long-term outcome of pulmonary vein isolation in combination with electrogram-guided substrate ablation for persistent atrial fibrillation.

Complex fractionated atrial electrographic (CFAE) catheter ablation is a new approach for the treatment of atrial fibrillation (AF). It is unclear if acute results of this approach correspond to long-term outcome. The purpose of this study was to prospectively assess acute and long-term successes of an ablation approach combining pulmonary vein isolation (PVI) and ablation of CFAE areas for treatment of persistent AF. PVI and ablation of CFAE areas were performed in 35 patients with persistent AF (30 men, 57+/-9 years of age). At the end of the ablation procedure AF had terminated in 23 of 35 patients (66%) by conversion to sinus rhythm (8 of 23 patients, 35%) or organization to atrial tachycardia (15 of 23 patients, 65%). AF persisted in 12 of 35 patients (34%). At the end of the follow-up period (19+/-12 months), sinus rhythm was present in 26 of 35 patients (74%), including 9 patients with a repeat procedure. This group of 26 patients consisted of 7 of 8 patients (88%) with acute sinus rhythm after the first ablation, 11 of 15 patients (73%) with organization, and 8 of 12 patients (66%) with ongoing AF (p=0.32). In conclusion, a combined approach of PVI and CFAE ablation in persistent AF leads to acute AF termination in 66% and long-term maintenance of sinus rhythm in 74% of cases. However, long-term outcome was not predictable by acute results of the ablation procedure.

Radiofrequency ablation of complex fractionated atrial electrograms (CFAE): preferential sites of acute termination and regularization in paroxysmal and persistent atrial fibrillation.

INTRODUCTION: Complex fractionated atrial electrograms (CFAE) have been described as a new target for ablation of atrial fibrillation (AF). This prospective study evaluates the acute effects of CFAE ablation in patients with paroxysmal or persistent AF and analyzes the preferential anatomic sites where these effects occur. METHODS AND RESULTS: Ablation of CFAE was performed in 66 symptomatic patients (mean age of 58 +/- 12 years) with paroxysmal (n = 36) or persistent AF (n = 30). Termination or regularization of AF during ablation of CFAE was achieved in 56 of 66 patients (84%), with termination in 28 of 66 patients (42%) and regularization of AF in 28 of 66 patients (42%). Ablation of CFAE showed no effect in 10 of 66 patients (16%). Termination of AF occurred at 53 sites and AF regularization at 81 sites. The preferential sites of AF termination or regularization were found around the pulmonary veins (termination n = 15; regularization n = 22), at the anterior wall (termination n = 14; regularization n = 19) and at the interatrial septum (termination n = 8; regularization n = 17). CONCLUSION: Termination or regularization of AF was achieved acutely in 84% of patients by ablation of CFAE. The preferential sites of AF termination or regularization were found around the pulmonary veins, at the anterior wall of the LA and at the interatrial septum. These findings may have implications for future ablation concepts.

Catheter ablation of left atrial focal tachycardia guided by electroanatomic mapping and new insights into interatrial electrical conduction.

BACKGROUND: Experience in catheter ablation of left atrial (LA) focal tachycardia and information about interatrial electrical connections during LA focal tachycardia are limited. OBJECTIVES: The purpose of this study was to describe our experience in electroanatomic mapping-guided catheter ablation of LA focal tachycardia and to investigate interatrial electrical connections during LA focal tachycardias. METHODS: Thirty-three patients undergoing catheter ablation for LA focal tachycardia guided by electroanatomic mapping were reported. Interatrial electrical connections were analyzed in LA focal tachycardias with biatrial electroanatomic maps. RESULTS: Of the 35 LA focal tachycardias (cycle length 309 +/- 100 ms) mapped, 19 (54%) originated from the pulmonary veins (PVs), 6 (17%) from the mitral annulus, 3 (8.6%) from LA roof, 3 (8.6%) from LA posterior wall, 2 (5.7%) from LA appendage, and 2 (5.7%) from LA septum. Fourteen of the 19 PV tachycardias (74%) were located in proximity to PV ostia. In 14 (7 PV, 7 non-PV) LA focal tachycardias with biatrial electroanatomic maps, posterior right atrium breakthrough sites at the intercaval area were identified in 7 PV tachycardias and 1 non-PV tachycardia. Five of the 7 PV tachycardias used only the posterior breakthrough for interatrial propagation. Procedural success was achieved in 33 of 35 LA focal tachycardias (94%) in 31 patients. During 23 +/- 19 months of follow-up, 2 patients (6%) had recurrence of ablated tachycardia, and 3 (10%) developed new LA focal tachycardias. CONCLUSIONS: The PVs and the mitral annulus were the main sources of LA focal tachycardias. The majority of PV tachycardias originated from PV ostia. A posterior interatrial connection appeared to play a major role in interatrial electrical propagation during PV tachycardias. Electroanatomic mapping facilitated precise localization of LA focal tachycardias and achievement of a high rate of ablation success.

Rescue ablation of electrical storm in patients with ischemic cardiomyopathy: a potential-guided ablation approach by modifying substrate of intractable, unmappable ventricular tachycardias.

OBJECTIVES: The purpose of this study was to evaluate a substrate-modifying, primarily potential-guided catheter ablation approach as a bailout therapy in patients with complex myocardial infarction and electrical storms due to ventricular tachycardias (VTs). BACKGROUND: Management of electrical storm is a domain of medical treatment. A definite trigger or delineated scar has been characterized as a requirement for substrate-orientated ablation of intractable unmappable ventricular tachyarrhythmias but can be absent, as shown in the presented cases. METHODS: Five patients who presented with ischemic cardiomyopathy and severe reduced left ventricular ejection fraction also suffered from multiple types of unstable VTs that deteriorated into drug-refractory electrical storm. Patients had 96 to 580 VT episodes requiring therapy with an implantable cardioverter-defibrillator (ICD) and received 3 to 310 shock deliveries prior to ablation. Treatment with beta-blockers, amiodarone, class IB antiarrhythmic drugs, deep sedation, and overdrive pacing and/or cardioversion of incessant VTs failed to stabilize the electrical storm but enabled left ventricular electroanatomic voltage mapping. A simplified substrate modification was performed by ablation of delayed fractionated potentials in areas identified by pace mapping, matching three to eight documented types of VTs per patient in complex scar areas. RESULTS: All patients could be stabilized after ablation. During 12 to 30 months of follow-up, three patients remained free of any VT episode requiring ICD treatment, and two patients had <1 VT episode per month. CONCLUSIONS: The cases presented demonstrate that rescue VT ablation of drug-refractory electrical storm is possible by a substrate-orientated ablation approach even in patients with complex chronic infarction and various VTs.