Ablation vs drug use for atrial fibrillation

The relative merits of rate and rhythm control in the treatment of patients with atrial fibrillation (AF) have been compared in several major clinical trials, none of which demonstrated a significant difference in all-cause mortality. Yet, there is clear evidence that restoration and maintenance of sinus rhythm is associated with beneficial reverse atrial and ventricular remodelling. In addition, patients may feel better if AF is resolved, and data from some post hoc analyses suggest a possible mortality benefit. These apparently contradictory findings may reflect the high risk of serious adverse events associated with currently available antiarrhythmic drugs (AAD), counterbalancing their beneficial effect in restoring sinus rhythm. Catheter ablation offers an alternative means of restoring sinus rhythm in patients with AF and several clinical trials have indicated superior outcomes in certain subgroups after ablation with or without AAD vs. antiarrhythmic therapy alone. This study reviews the relative advantages and actual use of catheter ablation and other therapeutic options in the treatment of AF, with or without concomitant heart failure or structural heart disease. Catheter ablation is recognized in the latest ACC/AHA/ESC guidelines as a valid second-line option in patients who have failed or were intolerant of first-line antiarrhythmic therapy. In the absence of new antiarrhythmics with an improved benefit/risk profile, it could become a first-line strategy for certain patient populations. The ongoing CABANA trial should confirm its impact on overall survival relative to that of pharmacological rate or rhythm control

An Approach to Catheter Ablation of Cavotricuspid Isthmus Dependent Atrial Flutter

Much of our understanding of the mechanisms of macro re-entrant atrial tachycardia comes from study of cavotricuspid isthmus (CTI) dependent atrial flutter. In the majority of cases, the diagnosis can be made from simple analysis of the surface ECG. Endocardial mapping during tachycardia allows confirmation of the macro re-entrant circuit within the right atrium while, at the same time, permitting curative catheter ablation targeting the critical isthmus of tissue located between the tricuspid annulus and the inferior vena cava. The procedure is short, safe and by demonstration of an electrophysiological endpoint - bidirectional conduction block across the CTI - is associated with an excellent outcome following ablation. It is now fair to say that catheter ablation should be considered as a first line therapy for patients with documented CTI-dependent atrial flutter

Noninvasive Assessment of Atrial Fibrillation Complexity in Relation to Ablation Characteristics and Outcome

Background: The use of surface recordings to assess atrial fibrillation (AF) complexity is still limited in clinical practice. We propose a noninvasive tool to quantify AF complexity from body surface potential maps (BSPMs) that could be used to choose patients who are eligible for AF ablation and assess therapy impact.Methods: BSPMs (mean duration: 7 ± 4 s) were recorded with a 252-lead vest in 97 persistent AF patients (80 male, 64 ± 11 years, duration 9.6 ± 10.4 months) before undergoing catheter ablation. Baseline cycle length (CL) was measured in the left atrial appendage. The procedural endpoint was AF termination. The ablation strategy impact was defined in terms of number of regions ablated, radiofrequency delivery time to achieve AF termination, and acute outcome. The atrial fibrillatory wave signal extracted from BSPMs was divided in 0.5-s consecutive segments, each projected on a 3D subspace determined through principal component analysis (PCA) in the current frame. We introduced the nondipolar component index (NDI) that quantifies the fraction of energy retained after subtracting an equivalent PCA dipolar approximation of heart electrical activity. AF complexity was assessed by the NDI averaged over the entire recording and compared to ablation strategy.Results: AF terminated in 77 patients (79%), whose baseline AF CL was 177 ± 40 ms, whereas it was 157 ± 26 ms in patients with unsuccessful ablation outcome (p = 0.0586). Mean radiofrequency emission duration was 35 ± 21 min; 4 ± 2 regions were targeted. Long-lasting AF patients (≥12 months) exhibited higher complexity, with higher NDI values (≥12 months: 0.12 ± 0.04 vs. <12 months: 0.09 ± 0.03, p < 0.01) and short CLs (<160 ms: 0.12 ± 0.03 vs. between 160 and 180 ms: 0.10 ± 0.03 vs. >180 ms: 0.09 ± 0.03, p < 0.01). More organized AF as measured by lower NDI was associated with successful ablation outcome (termination: 0.10 ± 0.03 vs. no termination: 0.12 ± 0.04, p < 0.01), shorter procedures (<30 min: 0.09 ± 0.04 vs. ≥30 min: 0.11 ± 0.03, p < 0.001) and fewer ablation targets (<4: 0.09 ± 0.03 vs. ≥4: 0.11 ± 0.04, p < 0.01).Conclusions: AF complexity can be noninvasively quantified by PCA in BSPMs and correlates with ablation outcome and AF pathophysiology

Cardiac Interventional Guidance using Multimodal Data Processing and Visualisation: medInria as an Interoperability Platform

Midas JournalmedInria is a free medical imaging software developed at Inria, which aims at providing clinicians with state-of-the-art algorithms dedicated to medical image processing and visualization. Efforts have been made to simplify the user interface, while keeping high-level algorithms. In this particular article, we will concentrate on its use in preoperative preparation for cardiac interventions, and how we handle the difficulties arising from the lack of standard format for data types such as meshes or fibers, the absence of a common programming interface for data processing algorithms, notably registration, and the issues of visualisation where display conventions would be beneficial

A new ECG-based method to guide catheter ablation of ventricular tachycardia

International audienceINTRODUCTION Catheter ablation is used to treat ventricular tachycardia (VT). It uses radiofrequency energy to destroy a small part of heart tissue that is causing rapid and irregular heartbeats. Automated localization of VT exit sites can facilitate the long and often challenging ablation procedures but current methods are not accurate enough, cannot be used in some conditions, and often require detailed information about the patient's anatomy. The aim of this study was to optimize the accuracy of a previously proposed computer-based method for localization of arrhythmia exit sites. The effectiveness of the method was tested using simulated ECG data. We looked for optimal settings of the method allowing to apply it in clinical conditions.METHODS The proposed algorithm works on any set of 3 or more ECG leads. The QRS complex integral (QRSi) of an ectopic beat is reduced to principal components (PCs) treated as coordinates of the exit site in ECG space and then projected to real space by a linear transformation based on a small number of QRSis paced at known locations. The accuracy of the method was tested on 8 patient-tailored models of the human heart and torso. For each model ~500 simulations were run, each for a different stimulus location. A set of training points was randomly chosen and all other locations were then estimated from simulated surface ECGs. The absolute and relative (to a neighboring stimulation site) localization errors (in mm) were computed for a 252-lead ECG, and Frank VCG and using different numbers of training points and principal components.RESULTS The localization error depended on the size of the training set. By using patient’s mean transform matrix of stimulus position from ECG space to real space and Frank XYZ leads we found 15.5 ± 6.4 mm of mean absolute error. Starting from 9 pacing positions available and 3 PCs used we reached a similar level of mean error (15.22 ± 3.5 mm). With 20 stimulus points available and 7 PCs we got 10 ± 2 mm of error. Added noise had no significant influence on the results; even a 2 dB signal/noise ratio increased the error by only 1 mm.DISCUSSION This study suggests that the proposed method can predict exit sites with a precision in the order of a centimeter. By dynamically switching the settings of the algorithm it is possible to obtain better accuracy

Shortening of Fibrillatory Cycle Length in the Pulmonary Vein During Vagal Excitation

ObjectivesThe goal of the present prospective study is to evaluate the impact of vagal excitation on ongoing atrial fibrillation (AF) during pulmonary vein (PV) isolation.BackgroundThe role of vagal tone in maintenance of AF is controversial in humans.MethodsTwenty-five patients (18 with paroxysmal AF, 7 with chronic AF) were selected by occurrence of vagal excitation during AF (atrioventricular [AV] block: R-R interval >3 s) produced by PV isolation. Fibrillatory cycle length (CL) in the targeted PV and coronary sinus (CS) were determined before, during, and after vagal excitation. The CL was available at PV ostium during vagal excitation in 11 patients.ResultsForty-eight episodes of vagal excitation were observed. During vagal excitation, CL abruptly decreased both in CS and PV (CS, 164 ± 20 ms to 155 ± 23 ms, p < 0.0001; PV, 160 ± 22 ms to 143 ± 28 ms, p < 0.0001), and both returned to the baseline value with resumption of AV conduction. The decrease in PVCL occurred earlier (2.5 ± 1.5 s vs. 4.0 ± 2.6 s, p < 0.01) and was of greater magnitude than that in CSCL (16 ± 16 ms vs. 8 ± 9 ms, p < 0.01). A sequential gradient of CL was observed from PV to PV ostium and CS during vagal excitation (138 ± 29 ms, 149 ± 24 ms, and 159 ± 26 ms, respectively). The decrease in CL was significantly greater in paroxysmal than in chronic AF (CS, 11 ± 9 ms vs. 5 ± 7 ms, p < 0.05; PV, 23 ± 25 ms vs. 8 ± 14 ms, p < 0.05).ConclusionsVagal excitation is associated with shortening of fibrillatory CL. This occurs earlier in PV with a sequential gradient to PV ostium and CS, suggesting that vagal excitation enhances a driving role of PV

VT Scan: Towards an Efficient Pipeline from Computed Tomography Images to Ventricular Tachycardia Ablation

International audienceNon-invasive prediction of optimal targets for efficient radio-frequency ablation is a major challenge in the treatment of ventricular tachycardia.Most of the related modelling work relies on magnetic resonance imaging of the heart for patient-specific personalized electrophysiology simulations.In this study, we used high-resolution computed tomography images to personalize an Eikonal model of cardiac electrophysiology in seven patients, addressed to us for catheter ablation in the context of post-infarction arrhythmia.We took advantage of the detailed geometry offered by such images, which are also more easily available in clinical practice, to estimate a conduction speed parameter based on myocardial wall thickness.We used this model to simulate a propagation directly on voxel data, in similar conditions to the ones invasively observed during the ablation procedure.We then compared the results of our simulations to dense activation maps that recorded ventricular tachycardias during the procedures.We showed as a proof of concept that realistic re-entrant pathways responsible for ventricular tachycardia can be reproduced using our framework, directly from imaging data