Page 26 - Journal of Structural Heart Disease Volume 5, Issue 5

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Original Scientific Article
to sinus rhythm patients. Interestingly, the authors addressed a further challenging aspect of LAA assess- ment which is the definition of the LAA ostial plane. In their analysis, three planes were proposed for assess- ment of the LAA orifice. Due to the lack of anatomi- cal boundaries between the left atrial cavity and the LAA, it still remains challenging to uniformly define the plane of the ostium. So far, the most common- ly used plane for defining the LAA ostium is a plane joining the pulmonary vein ridge superiorly and the junction between the LA and the LAA inferiorly at the plane the left circumflex coronary artery. Of Interest, using a similarly defined plane in their cohort and ours, Hozawa et al. could only demonstrate a trend towards larger LAA ostial dimensions in AF patients compared to sinus rhythm, however these differenc- es did not reach statistical significance. These differ- ences could be probably explained by the difference in cohort size on one side, and more importantly due to the mere ventricular diastolic phase assessment in their cohort on the other side.
In light of our findings, it appears of relevant im- portance to plan the time of CT acquisition to the time point of maximal LAA dimensions for optimal device sizing and consequently optimal sealing of the LAA. However, we examined a cohort of patients re- ferred for CT imaging in the context of transcatheter aortic valve replacement, as these patients were – per institutional protocol - examined using retrospective acquisition and hence multiphase assessment of LAA dimensions at different time points of the cardiac cy- cle was possible. In so far, whether implementing CT maximal LAA dimensions for device sizing outside this selected cohort would affect intra-procedural success as well as complications remains unclear and need to be further assessed in a prospective cohort referred for percutaneous LAA occlusion.
Several limitations in this study need to be ac- knowledged. First, our patient cohort included a rel- atively small cohort referred for CT imaging prior to transcatheter aortic valve replacement. Furthermore CT measurements were performed by a single ob- server once so intra- and inter-observer differences could not be reported. However, our data shed light on the importance of careful timing of CT acquisi- tions in the context of LAA imaging prior to inter- ventional closure. The currently available literature is somehow heterogeneous as far as CT acquisition protocols prior to LAA occlusion are concerned. Espe- cially with the expected increase in CT imaging in this context, standardized acquisition protocols as well as reporting algorithms need to be developed to allow for standardized reporting. According to our data, to identify maximal LAA dimensions, CT imaging for the purpose of LAA occlusion should be targeted in atrial diastole (40-50% of the peak R-wave to R-wave).
Acknowledgment
We would like to express our sincere thanks to Mr. Tsuyoshi Nagata from Ziosoft for his help and assis- tance in the processing of the CT data sets as well as his continuous support with data analysis. The pres- ent work was carried out by Amina Vaillant to meet the requirements for obtaining the degree “Dr. med.” at Friedrich-Alexander-University Erlangen-Nürnberg (FAU).
Conflict of Interest
Mohamed Marwan has received speaker honoraria from Siemens Healthcare and Edwards Lifesciences.
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CT Sizing for LAA