Future Directions
Percutaneous cardiac procedure volumes have exploded in recent years as technical capabilities grow and more devices come to market. The primary goals of any procedure should be safety and efficacy. Efficiency and low cost must also be the aims as healthcare expenditures continue to grow ever higher. As procedures have expanded, so have correlating imaging techniques to enhance planning and meet those essential objectives. In LAAO procedures in particular, the critical information imaging modalities provide is the relevant anatomy of the LAA and how that impacts device selection. Given the excellent structural resolution of CMR and the data demonstrated by Dallan et al., CMR should be a safe and effective option in the future. We would suspect that with more experience, sizing accuracy would approach that of CT, improving the average number of devices needed per case and thereby lowering associated costs.
The cost of CMR may come down over time, and availability should improve. CMR certainly has the advantage of availability for patients with renal disease unable to receive significant contrast loads and can be obtained without general anesthesia. It may be of particular use when a patient with renal disease desires same-day discharge or has an aversion to TEE. The authors highlight CMR’s added information over CT, such as myocardial fibrosis and structural remodeling. It may be that CMR has enhanced utility in combined procedures, for instance, where an LAAO is performed with an ablation [9].
Beyond strictly procedural planning, CMR may have a use in the overall assessment of the LAA. There have been efforts to define better stroke risk based on imaging of the LAA [10], and CMR would seem to be an unexplored modality in this regard. CMR may also be helpful in post-LAAO follow-up, explicitly looking for device leaks, device thrombus, or evidence of endothelialization [11].
For the immediate future, CT is likely to remain the most utilized modality for LAAO planning. However, with more investigation, CMR should become a viable alternative and another tool for LAAO procedural planning.
References
1. Reddy, V.Y., et al., 5-Year Outcomes After Left Atrial Appendage Closure. Journal of the American College of Cardiology, 2017.70 (24): p. 2964-2975.
2. Khalil, F., et al., Utilization and procedural adverse outcomes associated with Watchman device implantation. Europace, 2021.23 (2): p. 247-253.
3. Beigel, R., et al., The Left Atrial Appendage: Anatomy, Function, and Noninvasive Evaluation. JACC: Cardiovascular Imaging, 2014. 7 (12): p. 1251-1265.
4. Möbius-Winkler, S., et al., Percutaneous left atrial appendage closure: Technical aspects and prevention of periprocedural complications with the watchman device. World J Cardiol, 2015.7 (2): p. 65-75.
5. Rajwani, A., et al., CT sizing for left atrial appendage closure is associated with favourable outcomes for procedural safety.European Heart Journal - Cardiovascular Imaging, 2016. 18 (12): p. 1361-1368.
6. Korsholm, K., et al., Expert Recommendations on Cardiac Computed Tomography for Planning Transcatheter Left Atrial Appendage Occlusion. JACC: Cardiovascular Interventions, 2020. 13 (3): p. 277-292.
7. Nadeem, F., et al., A New WATCHMAN Sizing Algorithm Utilizing Cardiac CTA. Cardiovascular Revascularization Medicine, 2021.33 : p. 13-19.
8. Dallan, L.A.P., et al., Novel Cardiac Magnetic Resonance Imaging-Based Sizing for Left Atrial Appendage Closure. Journal of Cardiovascular Electrophysiology, 2022.
9. Kuchynka, P., et al., The Role of Magnetic Resonance Imaging and Cardiac Computed Tomography in the Assessment of Left Atrial Anatomy, Size, and Function. Biomed Res Int, 2015. 2015 : p. 247865.
10. Yaghi, S., et al., Left Atrial Appendage Morphology Improves Prediction of Stagnant Flow and Stroke Risk in Atrial Fibrillation.Circ Arrhythm Electrophysiol, 2020. 13 (2): p. e008074.
11. Hong, S.N., et al., Cardiac Magnetic Resonance Imaging and the WATCHMAN Device. Journal of the American College of Cardiology, 2010.55 (24): p. 2785-2785.