Reproducibility of Cardiac Computed Tomography Classifications of Hypoattenuated Thickening and Peridevice Leak Following Left Atrial Appendage Closure.

Aims: To assess the reproducibility of interpreting hypoattenuated thickening (HAT) and peridevice leak (PDL) using cardiac computed tomography (CT) imaging following Watchman FLX left atrial appendage closure (LAAC).
Methods and Results: In this multicenter retrospective reproducibility study, 100 anonymized post-LAAC cardiac CT scans were evaluated within the same cardiac phase by an experienced and a novice rater blinded to prior evaluations. All scans were evaluated twice by each rater, assessing overall HAT and PDL categories as well as specific associated findings based on suggested algorithms for post-LAAC interpretation. Inter- and intra-rater agreement and reliability were evaluated using absolute agreement, Cohen's kappa and Kendall's tau for categorical variables, and mean difference, Bland-Altman plots, limits of agreement and intraclass correlation coefficients (ICC) for continuous variables.Within overall categories of both HAT and PDL, substantial agreement (kappa >0.61) and reliability (Kendall's tau-b  > 0.75) were observed. Specifically, identifying high-grade HAT (kappa >0.78) and distal patency (kappa >0.85) displayed the highest agreement within HAT and PDL interpretation. Meanwhile, measuring the height of the proximal screw hub cove represented the least reliable HAT assessment among both inter- and intra-rater comparisons (ICC<0.75), while suspected leak mechanism represented the least reproducible PDL measure.
Conclusion: Despite only minimal training of one rater, overall high levels of inter- and intra-rater agreement and reliability were observed across the chosen algorithms for interpretation of HAT and PDL following Watchman FLX LAAC. Prognostic implications of the included variables are to be explored in future trials and registries.
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