Cardiac computed tomography following Watchman FLX implantation: device-related thrombus or device healing?

Anders Dahl Kramer, Kasper Korsholm, Jesper Møller Jensen, Bjarne Linde Nørgaard, Srikara Peelukhana, Thomas Herbst, Rodney Horton, Saibal Kar, Jacqueline Saw, Mohamad Alkhouli, Jens Erik Nielsen-Kudsk*

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review


AIMS: Cardiac computed tomography (CT) is increasingly utilized during follow-up after left atrial appendage closure (LAAC). Hypoattenuated thickening (HAT) is a common finding and might represent either benign device healing or device-related thrombosis (DRT). The appearance and characteristics of HAT associated with the Watchman FLX have not been previously described. Therefore, we sought to investigate cardiac CT findings during follow-up after Watchman FLX implantation with a focus on HAT and DRT.

METHODS AND RESULTS: Retrospective single-centre, observational study including all patients with successful Watchman FLX implantation and follow-up cardiac CT between March 2019 and September 2021 (n = 244). Blinded analysis of CT images was performed describing the localization, extent, and morphology of HAT and correlated to imaging and histology findings in a canine model. Relevant clinical and preclinical ethical approvals were obtained.Overall, HAT was present in 156 cases (64%) and could be classified as either subfabric hypoattenuation (n = 59), flat sessile HAT (n = 78), protruding sessile HAT (n = 16), or pedunculated HAT (n = 3). All cases of pedunculated HAT and five cases of protruding sessile HAT were considered as high-grade HAT (n = 7). Subfabric hypoattenuation and flat sessile HAT correlated with device healing and endothelialization in histological analysis of explanted devices.

CONCLUSION: Subfabric hypoattenuation and flat sessile HAT are frequent CT findings for Watchman FLX, likely representing benign device healing and endothelialization. Pedunculated HAT and protruding HAT are infrequent CT findings that might represent DRT.

Original languageEnglish
JournalEuropean Heart Journal Cardiovascular Imaging
Pages (from-to)250-259
Number of pages10
Publication statusPublished - Feb 2023


  • Animals
  • Atrial Fibrillation
  • Dogs
  • Echocardiography, Transesophageal
  • Retrospective Studies
  • Thrombosis/diagnostic imaging
  • Tomography
  • Treatment Outcome


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