In the last few years novel ablative technologies featuring several devices incorporating different energy sources and catheter design for ensuring an effective PVI have been proposed. In particular, two prominent technologies, such as the non-thermal ablation modality based on pulsed field ablation (also defined as “electroporation”) and radio frequency balloon-based catheter has been introduced in the clinical practice. The adoption of such technologies aims at simplifying PVI procedures, improving efficacy, and increasing safety. Furthermore, the evaluation of the extension of area of lesion promoted by the two technologies might affect the clinical outcome

Reply by Casella et al to Letter Regarding Article,

The chance for the development of right AFL is strictly related to changes in functional conduction properties of the atrial myocardium which are greatly influenced by fibrotic/scar tissue and increased atrial volume. If these circumstances take place, reduction in conduction velocity can favor a macro-reentry circuit with the wavefront that does not meet its refractory tail and perpetuate the arrhythmia. Therefore, the time required to traverse the entire circuit is related to the circuit’s functional properties. With pacing from the coronary sinus os the right atrial collision time (RACT) of the two wavefronts traveling the circuit in counterclockwise and clockwise direction is calculated. in this prospective study, a cut-off of 115.5 ms of RACT showed a sensitivity and specificity of 92.7% and 93.0% respectively for diagnosis of AFL and an ROC curve indicated an AUC of 0.96 (95% CI: 0.93-1.0, p<0.01). Based on these premises, RACT could be utilized as new marker for the propensity of developing typical AFL.

Laser- based PVI has been around for many years and this modality of ablation is to provide a continuous circular overlapping lesions around the PVs' ostia. In order to ensure the continuity of the lesion, a camera is embedded in the system as to guide the placement of sequential applications with the target to make an adequate overlapping of two contiguous lesions as to reduce the likelihood of gaps. The first version of the system required the operator to manually rotate the catheter as to create a continuous arc of lesion around the PV's ostium. This approach is time-consuming, with a substantial overall time for each PV. The evolvement of the technique has been recently offered, with a novel semi-automated VGLA as to improve ablation efficiency by using a motorized system which moves the laser arc continuously in order to reduce the application time and, hopefully, minimize the creation of gaps.

Myocardial wall thickness is one of the crucial parameters affecting the lesion formation produced by radiofrequency current (RF) delivering. Knowing the tissue characterization is critical for improving the durability of the RF lesion. A novel dielectric based method (KODEX-EPD) has been developed for measuring the tissue thickness at the catheter-tissue interface. The authors of this study report for the first time the tissue characterization (i.e. atrial wall thickness) of the cavo-tricuspid isthmus in a series of patients undergoing common atrial flutter ablation, showing a higher thickness close to the tricuspid valve as compared to the inferior vena cava. This can affect the outcome of ablation

There is still uncertainity about the use of CT-scan for LAAO device sizing. The main reason for this disappointing position is likely to relate to the scarcity of robust data, since there is still difference among institutions with regards how to perform measurement of the devices. Dallan et al. (1) report their own experience on the use of a novel computed tomography angiography-based (CTA) for sizing the Watchman Flex device for left atrial appendage occlusion (LAAO) . The authors through the TruPlan software package that a pre-procedural CTA sizing protocol can be applied successfully with ICE guidance and provide excellent procedural outcomes.The applied CTA protocol is safe and can provide high success rates with the WatchmanTM FLX device reducing the number of deployment attempts and reducing the risk of complications.

The role of isolation of left posterior wall in patients with persistent atrial fibrillation on top of pulmonary vein isolation is still debatable. There are still technical issues for achieving complete left posterior wall isolation and durability of the lesions is probably the main limiting factor for promoting a successful clinical outcome