Purpose of Review: Atrial fibrillation (AF), the most common sustained arrhythmia, is associated with high rates of morbidity and mortality. Maintenance of stable sinus rhythm (SR) is the intended treatment target in symptomatic patients, and catheter ablation aimed at isolating the pulmonary veins provides the most effective treatment option, supported by encouraging clinical outcome data. A variety of energy sources and devices have been developed and evaluated. In this review, we summarize the current state of the art of catheter ablation of AF and describe future perspectives. Recent Findings: Catheter ablation is a wellestablished treatment option for patients with Enhanced Digital Features To view enhanced digital features for this article go to https://doi.org/10.6084/ m9.figshare.11357912.

Application of 2 when compared to 1 freeze-thaw cycle(s) following cryoballoon PVI did not result in improved clinical success but was associated with a higher complication rate.

We thank Drs Yamada and Kay for their comments regarding our article "Ventricular arrhythmias arising from the left ventricular outflow tract below the aortic sinus cusps: mapping and catheter ablation via transseptal approach and electrocardiographic characteristics." 1 The main issues raised by Drs Yamada and Kay focused around the transseptal approach used in our study to obtain better access to the area termed the LV summit.We agree with the authors that using the retrograde aortic approach and with the catheter inversion technique, some of the regions beneath the aortic sinus cusps (ASC) can be reached. However, when this is performed with the 3D mapping system, one can see that in the majority of the time, there is a distance between the left ventricular and the aorta maps. Given that the aortic valves are only millimeters thin, this suggests that the left ventricular map beneath the ASCs is not complete. This is likely because mapping with a looped mapping catheter from the retrograde aortic approach is dependent on the diameter of the aorta, the aortic valves themselves, and the left ventricular dimensions. When the ventricular arrythmias (VA) originate from an area further away from the ASCs, this does not pose a problem and ablation may be successful. However, when the origin of the VA is just below and near to the ASCs, in our experience this becomes difficult to ablate and achieve success. We have found that this area is best reached via the transseptal approach, and the left ventricular map abuts the aorta map during 3D-mapping with this approach. Addtionally in our study, the VAs could only be ablated via the transseptal approach in 6 patients who had undergone previous failed ablation with catheter inversion techniques via transaortic approach.Furthermore, we agree with the comment that mapping within the ASCs should be initially performed via the retrograde aortic approach. Because of the close anatomic relationship of the structures in this area, the ECG characteristics of VAs originating from above or below the ASCs are similar with great overlap. In a recent study, we found that the absence of prepotentials at the earliest site in the aortic sinus of Valsalva during VAs and a bigger aVL:aVR ratio >1.45 strongly indicates a VA origin from below the ASC. Finally, although a transseptal puncture at the anteroinferior fosa ovalis is not always safe, all transseptal punctures in this study were performed by highly experienced operators and guided by an ablation catheter placed in the noncoronary ASC. This outlines the anatomic location of the posterior wall of the aorta and minimizes the complication risk. In addition, it is our institutional standard that during such cases, the transseptal puncture is performed with an ACT >250 ms. DisclosuresNone.

Ablation of this type of VA is still challenging. Epicardially, it is bound by the left anterior descending artery, left circumflex artery, and the distal part of the great cardiac vein (GCV). The anatomic region superior to the GCV has been previously described as an area inaccessible to catheter ablation and the area inferolateral to the GCV as more accessible via epicardial ablation. 9 We sought to determine mapping, ablation, and ECG characteristics of VA originating from the anterosuperior LVOT via an antegrade transseptal approach. Clinical Perspective on p 455 Methods Study PopulationIn 2012 to 2013, 27 consecutive patients with symptomatic VAs and with ECGs suggestive of VAs arising from the anterosuperior LVOT underwent radiofrequency ablation at 3 centers: 13 patients at © 2014 American Heart Association, Inc. Original ArticleBackground-Ventricular arrhythmias (VAs) originating from the anterosuperior left ventricular outflow tract (LVOT) represent a challenging location for catheter ablation. This study investigates mapping and ablation of VA from anterosuperior LVOT via a transseptal approach. Methods and Results-This study included 27 patients with symptomatic VA, of which 13 patients had previous failed ablations. LVOT endocardial 3-dimensional mapping via retrograde transaortic and antegrade transseptal approaches was performed. Previous ECG markers for procedure failure were analyzed. In all patients, earliest activation with lowamplitude potentials was identified at the anterosuperior LVOT 5.1±2.8 mm below the aortic cusp and preceded the QRS onset by 39.5±7.7 ms only via an antegrade transseptal approach using a reversed S curve. In all patients, pace mapping failed to demonstrate perfect QRS morphology match. The anatomic location was below the left coronary cusp in 16, below the left coronary cusp/right coronary cusp junction in 8, and below the right coronary cusp in 3 patients. Radiofrequency energy resulted in rapid disappearance of VAs in all patients. ECG analysis showed aVL/aVR Q-wave amplitude ratio >1.4 in 7, lead III/II R-wave amplitude ratio >1.1 in 10, and peak deflection index >0.6 in 11 patients. There were no complications or clinical VA recurrence during a mean follow-up of 8.4±2.5 months. Conclusions-The anterosuperior LVOT can be reached via a transseptal approach with a reversed S curve of the ablation catheter. The rapid effect from radiofrequency energy indicates that the VA is most likely located under the endocardium. Also, previous ECG markers for procedure failure need further investigation. Asklepios Klinik St. Georg, Hamburg, 10 at the 1st Affiliated Hospital of Nanjing Medical University, Nanjing, and 4 at the Guangdong Provincial People's Hospital, Guangzhou. All patients underwent physical examination, 12-lead ECG, 24-hour Holter monitor, and transthoracic echocardiogram to assess left ventricular (LV) function before ablation. Transesophageal echocardiography was only performed to exclude left atrial thrombus in older patients because of the potential risk of asy...