The Role of CT-scan
Over the years, several discussions about the use of CT-scan for LAA occluder device sizing have been raised by investigators, leading to non-homogeneous conclusions. 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. In several institutions, the pre-procedural device sizing is guaranteed by TEE carried out at the same time of thrombus evaluation in LAA. Therefore, even for the workflow’s sake, CT-scan is no strictly required and the procedure itself relies on sizing obtained by fluoroscopy and TEE in real time during the procedure.
One could raise the question whether pre-procedural CT-scan is critical for identifying the right device sizing and, thus if it should become the standard approach for LAA closure. Based on the preliminary data offered by Dallan and co-workers, it seems that the novel TruPlan software accurately provides the size of device and it might also improve the patient’s workflow in the lab. Moreover, they did not observe device embolization, nor strokes or any other major complications. The CT sizing strategy adopted by the authors was associated with only 1.04 devices used per patient. Furthermore, this approach yielded a 99% procedural success and 99% closure rate at 45-day follow up which compares with previous clinical outcome reported with TEE (7,8). In other words, the CT sizing through the TruPlan software does not negatively affect the outcome of Watchman Flex device. Actually, based on these results, very comparable to the current use of intraprocedural TEE and/or ICE, the operators have their own choices of how to perform LAAO intervention. Then, which is the real novelty for the physicians provided by the TruPlan software? First, the methodology of LAA measurements based on an area-derived diameter as opposed to the maximum diameter currently offered by CT technique provides a more adequate device sizing thus, reducing the likelihood of device over-compression. In fact, sizing and compression estimates are derived automatically, and device selection can be chosen based on area-derived diameter. Moreover, it seems even more crucial the role of the TruPlan software in selecting the most adequate device when two device sizes fit within the recommended 10-30% compression range. Under these circumstances, the algorithm would select a larger device at higher compression if accommodated by appendage depth. Once selected, TruPlanTM digitally superimposes the device onto the CT image of the appendage. The device overlay feature is certainly a key element in decision-making, to assess adequacy of fit. Then, the device can be virtually repositioned in the appendage to predict how appendage tissue might interact with the device upon implant. Interestingly, the program simulates device shape at any predicted compression, forecasting how the device will appear fluoroscopically in the appendage.