Atrial fibrillation (AF) which is the most common cardiac arrhythmia in advanced age is associated with the risk of intracardiac thrombus formation and the occurrence of stroke and systemic embolism. Oral anticoagulation (OAC) is nowadays the standard therapy for patients with AF who have an increased risk of stroke (1). However, a number of these patients develop bleeding complications that require discontinuation of OAC. In this situation, interventional closure of the left atrial appendage (LAA closure, LAAC) represents an established treatment alternative (2).
In the majority of cases, left atrial appendage closure (LAAC) is performed as a transvenous catheter-based procedure. To enable correct placement of the occluder, the procedure is usually guided by both angiography (x-ray fluoroscopy) and transesophageal echocardiography (TEE). However, the use of TEE requires either general anesthesia or at least conscious sedation, which both are associated with potential threats and inconveniences to the patient. In addition, TEE per se carries the risk of injury to the pharynx and esophagus. In a recent study it has been reported that in patients who underwent a TEE-guided cardiac intervention, lesions in the esophagus caused by TEE could be detected in 86% of all cases by endoscopy (3). Another study showed that prolonged use of TEE during structural interventions resulted in clinically relevant complications in 6.1% of cases (4).
Against this background, it seems desirable to be able to perform LAAC without TEE. This is possible, for example, by using intracardiac echocardiography (ICE) instead. The feasibility of ICE-guided LAAC has been shown previously (5), but this method requires a second or enlarged transseptal access and is associated with an increase of procedure-related costs thereby limiting its clinical use. Alternatively, it also has been described that LAAC might be performed without any ultrasound-based imaging modality by the implementation of 3D rotational angiography (6). However, this technique is depending on a temporary "cardiac arrest" through tachypacing and leads to a rise of exposure to X-ray contrast medium and radiation, respectively.
In principle, the use of TEE during LAAC is considered helpful or necessary especially at certain key steps during the procedure. First, TEE is used to guide transseptal puncture (TSP) to determine the ‘optimal’ puncture site within the interatrial septum thereby potentially achieving the most favorable access to the LAA which could facilitate the further course of the procedure. Nevertheless, so far there are no clinical studies which actually have shown an advantage of TEE-guided TSP on the final result of the LAAC procedure in respect to device positioning or completeness of LAA sealing etc.. Second, the use of TEE during TSP is considered to reduce the risk of pericardial tamponade. However, TSP is nowadays performed in daily routine without TEE in a large number of other cardiac interventions (e.g. pulmonary vein isolation etc.) without a relevant risk of cardiac tamponade so that TEE can be considered dispensable in this regard. Third, TEE is used to rule out intracardiac thrombi and to determine the size of the LAA in order to select the suitable size of the LAAC device although these tasks can be completed already before the implantation procedure either by diagnostic TEE or preferably by cardiac CT. Finally, the perhaps most important role of TEE in LAAC is to confirm the correct positioning of the occluder before the device is released definitely. For the WATCHMAN, so called “PASS criteria” are applied (position, anchor, size, seal) which according to IFU should be checked by TEE albeit in principle it is possible to perform this evaluation also based on fluoroscopy.
Against the background of these explanations, the assumption is justified that nowadays LAAC can be performed safely under sole fluoroscopic guidance without the need for intraprocedural ultrasound. This hypothesis is based on the existing clinical experience regarding the technique of left atrial appendage closure and the technical improvements that have been implemented into the development of new generation LAAC systems.