Automatic identification of ablation targets in persistent atrial fibrillation: Initial experience with a new mapping tool.

INTRODUCTION: Strategies beyond pulmonary vein isolation (PVI) in persistent atrial fibrillation (persAF) are debated. A novel mapping tool provides algorithmic detection of ablation targets based on electrogram (EGM) properties specific to stable localized rotational activations. METHODS: The mapping tool was used on 31 patients (20 de novo). The algorithm was used to optimize PVI line placement and guide additional ablations. Targets were detected by calculating local cycle length (L-CL) and local spread of activation within that L-CL (Duty Cycle; DC) for EGMs with consistent morphology and activation. At least two left atrial (LA) maps (pre-PVI and post-PVI) were acquired in atrial fibrillation (AF) in all patients (except those with AF termination during PVI). Extra-pulmonary vein (PV) targets were compared between the two LA maps in each patient. Follow-up included Holter monitoring every 3 months. RESULTS: Patients had a median of 3 extra-PV drivers/targets. The majority (81%) were localized in the same areas between the two LA maps. All patients had progressive AF organization demonstrated by global activation slowing: histogram peak L-CL increased from 162 to 171 ms (post-PVI; p = .0003) than to 175 ms (posttarget ablation; p = .04). Moreover, L-CL dispersion was reduced by ablation; in 50% their values tended to cluster around two dominant cycles. In de novo patients AF terminated to sinus rhythm or atrial tachycardia (AT) within 48 h postprocedure in 88% of cases, and at 18 months mean follow-up recurrence occurred in only five (25%) patients (three persAF, two AT). There were no complications. CONCLUSION: The algorithmic detection of EGMs consistent with localized reentry during sequential mapping of persAF provided reproducible targets for ablation. This allowed personalized PVI and limited, highly-selective, extra-PV ablation. Results of this initial experience included progressive organization of AF with ablation and a low recurrence rate after a single procedure.

Sequential ultrahigh-density contact mapping of persistent atrial fibrillation: An efficient technique for driver identification.

INTRODUCTION: Literature supports the existence of drivers as maintainers of atrial fibrillation (AF). Whether ultrahigh density (UHD) contact mapping may detect them is unknown. METHODS: We sequentially mapped the left atrial (LA) activation during spontaneous persistent AF and performed circumferential pulmonary vein isolation (CPVI), followed by remapping and ablation of potential drivers (rotational and focal propagation sites) with Rhythmia™ in 90 patients. The time reference was an LA appendage (LAA) electrogram (EGM). Regions with uniform color were defined as "organized." Only patients (51) with no previous ablation were considered for acute results and follow-up reporting. RESULTS: LA maps (175 ± 28 ml, 43578 ± 18013 EGM) were acquired in 23 ± 7 min. In all post-CPVI maps potential drivers (7.3 ± 3.2/patient) were visualized: 85% with rotational propagation and continuous low voltage in the center; the remaining with focal propagation and an organized EGM at the site of earliest activation. The RF delivery time for extra-PV driver ablation was 12.2 ± 7.9 min. There was a progressive increase of AF organization: the LAA cycle length prolonged, the number of potential drivers decreased, and the organized LA surface in AF increased from 14 ± 6% to 28 ± 16% (p = .0007). Termination of AF without cardioversion was obtained in 67%. AF recurrence rate at 15 ± 7.3 months was 17.6% after the first procedure. CONCLUSIONS: Sequential UHD contact activation mapping of persistent AF allows visualization of potential drivers. A sequential strategy of CPVI followed by ablation of potential drivers with limited RF time resulted in an increasing organization of AF and good acute and long-term results.

Electrophysiologic evidence of epicardial connections between low right atrium and remote right atrial region or coronary sinus musculature: Relevance for catheter ablation of typical atrial flutter.

BACKGROUND: The coronary sinus (CS) is surrounded by a myocardial coat with extensive connections to the left and right atria that contributes to the interatrial electrical connection. Whereas epicardial connections between CS musculature and the left atrium have largely been demonstrated, clinically relevant epicardial connections from the CS musculature toward the low right atrium (LRA) and epicardial connections between two regions of the right atrium remain questionable. METHODS: Five patients underwent electrophysiology (EP) study for typical atrial flutter (AFl) using either conventional multipolar catheters (four patients) or three-dimensional high-density mapping system (one patient). RESULTS: All five patients had a similar sequence of events during the EP studies. After several cavotricuspid isthmus (CTI) radiofrequency (RF) applications, double potentials were recorded along the ablation line while tachycardia persisted. The right atrial activation pattern strongly suggested the presence of a complete endocardial CTI line of the block. Based on the detailed conventional atrial mapping, RF applications at the middle cardiac vein/CS ostium allowed sinus rhythm restoration in four patients. High-density mapping showed an early breakthrough site at the septal side of the ablation line, close to the CS ostium during counterclockwise AFl, in the fifth patient. RF applications at this site resulted in tachycardia termination. CONCLUSION: Our observations suggested the existence of epicardial fibers connecting the LRA with either the CS musculature or a remote right atrial region. When AFl ablation fails whereas evidence for the local endocardial block is observed, the operators should integrate this finding in the diagnosis and ablation strategy.

Cavotricuspid isthmus is constantly a zone of slow conduction: Data from ultra-high-resolution mapping.

BACKGROUND: Whether cavotricuspid isthmus (CTI) is a region of conduction slowing during typical flutter has been discussed with conflicting results in the literature. We aimed to evaluate conduction velocity (CV) along the different portions of the typical flutter circuit with a recently proposed method by means of ultra-high-resolution (UHR) mapping. METHODS: Consecutive patients referred for typical atrial flutter (AFL) ablation underwent UHR mapping (Rhythmia, Boston Scientific). CVs were measured in the CTI as well as laterally and septally, respectively, from its lateral and septal borders. RESULTS: A total of 33 patients (mean age: 65 ± 13 years; right atrial volume: 134 ± 57 mL) were mapped either during ongoing counterclockwise (n = 25), or clockwise (n = 3) AFL (mean cycle length: 264 ± 38 ms), or during coronary sinus pacing at 400 ms (n = 1), 500 ms (n = 1), or 600 ms (n = 3). A total of 13 671 ± 7264 electrograms were acquired in 14 ± 9 min. CTI CV was significantly lower (0.56  ± 0.18 m/s) in comparison with the lateral CV (1.31 ± 0.29 m/s; P < .0001) and the septal border CV of the CTI (1.29 ± 0.31 m/s; P < .0001). CONCLUSION: UHR mapping confirmed that CTI CV was systematically twice lower than atrial conduction velocities outside the CTI.

Ultrasound-guided axillary vein puncture for cardiac devices implantation in patients under antithrombotic therapy.

BACKGROUND: Ultrasound-guided axillary venous puncture (UGAVP) for cardiac devices implantation has been developed because of its rapidity, safety and potential long-term lead protection. Early work excluded defibrillators (ICD), cardiac resynchronization therapy (CRT) and upgrade procedures. Compared to the cephalic approach, in previous studies, there was a greater use of pressure dressings with this technique, suggesting a higher risk of bleeding. AIMS: To assess UGAVP in patients under antithrombotic therapy (ATT) undergoing cardiac devices implantation including CRT/ICD. METHODS: Prospectively, consecutive patients eligible for a pacemaker or ICD implantation were included. All procedures were performed by a single operator, experienced with UGAVP for femoral access, and fluoroscopy-guided axillary vein access. Guidewires insertion time (from lidocaïne administration), and complications were systematically studied. RESULTS: From 457 cardiac device implantations, 200 patients (77.8 ± 10 y, male 58%) 360 leads were implanted by UGAVP including 36 ICD, 54 CRT and 14 upgrade procedures. A majority (90%) was under ATT: Vitamin K Antagonist or Heparin (n = 58, 29%), direct oral anticoagulant (n = 46, 23%), dual antithrombotic therapy (n = 18, 9%) and single antiplatelet drug (n = 82, 41%). UGAVP was successful in 95.78%. Mean insertion time for 1.8 guidewires per patient was 4.68 ± 3.6 min. No complication (no hematoma) was observed during the follow-up (mean of 45 ± 10 months). Guidewires insertion time reached its plateau after 15 patients. CONCLUSION: UGAVP is fast, feasible and safe for patients under ATT undergoing device implantation including CRT/ICD and upgrade procedures, with a short learning curve.

High-resolution/Density Mapping in Patients with Atrial and Ventricular Arrhythmias.

High-definition/ultra-high-definition mapping, owing to an impressive increase of the point density of electroanatomic maps, provides improved substrate characterization, better understanding of the arrhythmia mechanism, and a better selection of the ablation target in patients with atrial and ventricular arrhythmias. Despite the scarce comparative data on ablation results versus standard mapping, ultra-high-definition mapping is increasingly used by the electrophysiology community.

How is Contact Force implemented in routine clinical practice? Results from a French National and Monaco Survey.

BACKGROUND: Combination of elementary parameters (force, time, power, impedance drop) has been proposed to optimize radiofrequency (RF) delivery. They have been partially validated in clinical studies. AIMS: The aim of this study was to assess contact-force (CF) implementation into clinical practice. METHODS: A 36-question electronic form was sent to 105 electrophysiologists (EP) including some general questions concerning the practice of catheter atrial fibrillation ablation and items concerning the parameters used for CF-guided ablation. RESULTS: Answers from 98 EP were collected (93% response rate). The CF-catheters used were Smart Touch, Biosense (52%), Tacticath, Saint-Jude Medical (12%), or both (27%) and no CF (9%). The power applied on the left atrial (LA) anterior (LAAW) and posterior (LAPW) wall was, respectively, 26-34 W (for 73% of the EP) and below 25 W (88% of the EP). Forty percent of the Visitag® users mostly used the nominal parameters. Seventy-five percent of the users did not use automatic display of the impedance drop. For the Tacticath users, 57% used a target value of 400 gs on the LAAW and 300 to 400 gs on the LAPW. Lesion Size Index was exceptionally used. CONCLUSIONS: The parameters used for CF-guided ablation are widely variable among the different operators. Further prospective studies are needed to validate the targets for automatic annotation of the RF applications.

Electrocardiographic modifications induced by breast implants.

BACKGROUND: Echocardiography realization can be challenging in the presence of breasts implants (BI). It is less known if electrocardiograms (ECG) may be modified in the presence of BI. METHODS: ECG from women with BI (and without any known cardiac structural disease) were sent and analyzed by two experienced electrophysiologists (EP1 and EP2) who were blinded and completely unaware of the context of the patients (Group 1). ECG from a control matched-group of female women without BI (Group 2) were also blindly sent for analysis. RESULTS: ECG were collected from 28 women with BI (42 ± 8 years) without any acute medical condition. A proportion of 42% of the ECG were considered abnormal by EP1 and 46% by EP2. The abnormalities were for EP1: negative T waves (5), ST depression in inferolateral leads (2), absence of R wave progression from V1 to V4 (4), left ventricular (LV) hypertrophy (1), long QT(1), early repolarization (1), short PR (1); For EP2: negative T waves (6), ST depression in inferolateral leads (2), absence of R wave progression from V1 to V4 (4), LV hypertrophy(3), long QT (1), early repolarization (1). ECG from group 2 were considered abnormal in only 1 patient (5%) for EP1, and normal in all for EP2 (P = 0.0002 between the groups). CONCLUSIONS: ECG from women with BI were considered abnormal in 42% to 46% of the cases by expert readers. ECG interpretation can thus be misleading in these women.

Scar identification, quantification, and characterization in complex atrial tachycardia: a path to targeted ablation?

Successful catheter ablation of scar-related atrial tachycardia depends on correct identification of the critical isthmus. Often, this is a represented by a small bundle of viable conducting tissue within a low-voltage area. It's identification depends on the magnitude of the signal/noise ratio. Ultra-high density mapping, multipolar catheters with small (eventually unidirectional) and closely-spaced electrodes improves low-voltage electrogram detection. Background noise limitation is also of major importance for improving the signal/noise ratio. Electrophysiological properties of the critical isthmus and the characteristics of the local bipolar electrograms have been recently demonstrated as hallmarks of successful ablation sites in the setting of scar-related atrial tachycardia.

Corrigendum.

[This corrects the article DOI: 10.1016/j.hrcr.2018.07.002.].

Coronary Sinus Activation and ECG Characteristics of Roof-Dependent Left Atrial Flutter After Pulmonary Vein Isolation.

BACKGROUND: The electrocardiographic and intracardiac activation features of left atrial roof-dependent macroreentrant flutter have been incompletely characterized. METHODS: Patients post-pulmonary vein (PV) isolation with roof-dependent atrial flutter based on activation and entrainment mapping were included. ECG and coronary sinus activation were compared with mitral annular (MA) flutter. RESULTS: The roof-dependent left atrial flutter circled the right PVs in 32 of 33 cases. Two forms of roof flutters were identified, posteroanterior, ascendant on posterior wall and descendant on anterior wall (n=24); and anteroposterior, ascendant on the anterior wall and descendent on the posterior wall (n=9). Both forms had positive large amplitude P waves in V1 through V2 with decreasing amplitude in V3 through V6. Posteroanterior roof flutters had positive P wave in the inferior and negative P wave in leads I and aVL similar to counterclockwise MA flutter, but coronary sinus activation was simultaneous for roof and proximal to distal for counterclockwise. Anteroposterior roof flutters were similar to clockwise MA flutter with negative P in inferior leads and transition to flat or negative P in V3 through V6. Coronary sinus activation time ≤39 ms identified roof versus MA flutter (sensitivity: 100% and specificity: 97%). CONCLUSIONS: Roof-dependent flutter around right PVs is more common than around left PVs. The ECG pattern for roof-dependent flutter around right PVs is similar to MA flutter with frontal plane axis dictated by septal activation. Roof-dependent flutter can be distinguished from MA flutter by more simultaneous rather than sequential coronary sinus activation.

A comparison between multipolar mapping and conventional mapping of atrial tachycardias in the context of atrial fibrillation ablation.

BACKGROUND: Activation mapping can be challenging and time-consuming in patients with multiple atrial tachycardias (ATs). AIMS: To compare multielectrode mapping using a dedicated mapping catheter - PentaRay (Biosense Webster Inc.) - and the conventional technique for mapping ATs in the context of atrial fibrillation (AF) ablation. METHODS: All procedures where PentaRay mapping of AT were used - after or during persistent AF ablation - were analysed. These were compared to a historical group - using conventional mapping. RESULTS: A mean of 449±520 points within 14±6min were acquired per AT in the PentaRay group (n=17) versus 42±18 points (P<0.0001) within 33±25min (P=0.04) in the conventional group (n=17). All 25 AT isthmuses were easily identified and ablated in the PentaRay group (100%) versus 20/23 (87%) in the conventional group (P=0.056). The ablation time was shorter in the PentaRay group (760±540 vs 1347±962 s; P=0.037). However, procedure and fluoroscopy times were not significantly different between the PentaRay and conventional groups: 253±77 vs 267±73min (P=0.80) and 13.1±8.0min vs 15.1±10.0min (P=0.98), respectively. Recurrence occurred in less patients in the PentaRay group (0 vs 23.5%; P=0.033) during a mean follow-up of nearly 1 year. CONCLUSION: In patients with multiple ATs, multielectrode PentaRay mapping was faster than the conventional technique, with less radiofrequency delivery and a better mid-term outcome.

Spectral and spatiotemporal variability ECG parameters linked to catheter ablation outcome in persistent atrial fibrillation.

With the increasing prevalence of atrial fibrillation (AF), there is a strong clinical interest in determining whether a patient suffering from persistent AF will benefit from catheter ablation (CA) therapy at long term. This work presents several regression models based on noninvasive measures automatically computed from the standard 12-lead electrocardiogram (ECG) such as AF dominant frequency (DF), spectral concentration and spatiotemporal variability (STV). Sixty-two AF patients referred to CA were enrolled in this study. Forty-seven of them had no recurrence after CA during an average follow-up of 14 ± 8 months. The ECG features were extracted from an ECG recorded before the CA intervention and they were combined by means of logistic regression. The combination of DF and STV values from different precordial leads reached AUC = 0.939, outperforming the best results by using only one kind of features, such as DF (AUC = 0.801), and yielding a global accuracy of 93.5% for discriminating the best long-term responders to CA. These results point out the need to take into consideration the spatial variation of spectral ECG parameters to build predictive models dealing with AF.

Radiofrequency catheter ablation of atrial fibrillation: Electrical modification suggesting transmurality is faster achieved with remote magnetic catheter in comparison with contact force use.

BACKGROUND: Remote magnetic navigation (RMN) and contact force (CF) sensing catheters are available technologies for radiofrequency (RF) catheter ablation of atrial fibrillation (AF). Our purpose was to compare time to electrogram (EGM) modification suggesting transmural lesions between RMN and CF-guided AF ablation. METHODS AND RESULTS: A total of 1,008 RF applications were analyzed in 21 patients undergoing RMN (n = 11) or CF-guided ablation (n = 10) for paroxysmal AF. All procedures were performed in sinus rhythm during general anesthesia. Time to EGM modification was measured until transmurality criteria were fulfilled: (1) complete disappearance of R if initial QR morphology; (2) diminution > 75% of R if initial QRS morphology; (3) complete disappearance of R' of initial RSR' morphology. Impedance drop as well as force time integral (FTI) were also assessed for each application. Mean CF at the beginning of each RF application in the CF group was 11 ± 2 g and mean FTI per application was 488 ± 163 gs. Time to EGM modification was significantly shorter in the RMN group (4.52 ± 0.1 seconds vs. 5.6 ± 0.09 seconds; P < 0.00001). There was no significant difference between other procedural parameters. CONCLUSION: Remote magnetic AF ablation is associated with faster EGM modification suggesting transmurality than optimized CF and FTI-guided catheter ablation.

Selection of Critical Isthmus in Scar-Related Atrial Tachycardia Using a New Automated Ultrahigh Resolution Mapping System.

BACKGROUND: Accurate activation mapping of reentrant scar-related atrial tachycardias (AT) allows efficient radiofrequency ablation by targeting the critical isthmus (CI). We aimed to assess the electrophysiological properties of CI channels during mapping with the IntellaMap Orion basket and the Rhythmia system. METHODS AND RESULTS: We prospectively studied 33 AT (post- atrial fibrillation ablation or surgical mitral valve repair). The noise of bipolar electrogram (EGM) was systematically measured at 10 prespecified sites, as well as on a standard catheter and on the surface ECG. Bipolar EGM of CI regions were analyzed for amplitude, duration, and conduction velocity. The isthmus region to be targeted was chosen based solely on propagation. For each AT, 25 684±14 276 EGMs were automatically annotated. Noise of the Orion EGM was 0.011±0.004 mV, lower than that of a standard catheter (0.016±0.019) and surface ECG (0.02±0.01; P<0.05). For reentrant AT, within the CI, bipolar EGM amplitude (0.08±0.11 mV) and conduction velocity (0.27±0.19 m/s) were lower than those orthodromically before (0.62±0.93 mV; 1±0.49 m/s) and after (0.80±1.59 mV; 1±0.73 m/s) the isthmus (P<0.001 for all). In 97% of AT, ablation at the CI resulted in AT termination. No complications occurred. CONCLUSIONS: This new automated ultrahigh resolution mapping system produces low noise and allows accurate diagnosis of AT circuits. CI on reentrant scar-related AT showed much lower EGM amplitude with a significantly slower conduction velocity than the surrounding parts of the circuit. Ablation of the areas of slow conduction resulted in a high acute success.