# False-Positive PET Uptake in Left Atrial Appendage Closure Devices Due to Postoperative Inflammatory Response

## TL;DR

This study shows that increased PET uptake in heart closure devices is likely due to inflammation, not infection, reducing false positives in cardiovascular infection diagnosis.

## Contribution

The study identifies postoperative inflammatory response as the cause of PET uptake in LAACDs, offering a new insight into diagnostic interpretation.

## Key findings

- 93% of PET scans showed homogeneous uptake in LAACDs, unrelated to infection.
- Clinical follow-up confirmed no device-related infections despite PET findings.
- SUV ratios were similar across different clinical indications and infection statuses.

## Abstract

Background: Positron emission tomography (PET) is a valuable tool in the diagnosis of cardiovascular infections. However, increased radiotracer uptake can also be observed in non-infectious inflammatory processes, leading to potential false positives. This study analyzed the uptake related to left atrial appendage closure devices (LAACD—AtriClip®) to determine its association with infectious or inflammatory processes. Methods: We retrospectively analyzed 28 PET/CT scans from 20 patients with implanted LAACDs: 24 using 18F-fluorodeoxyglucose (FDG) and 4 using 18F-Choline (CHO). Clinical, laboratory, and imaging data were reviewed, and PET uptake was measured semi-quantitatively. All patients had at least 12 months of follow-up after PET imaging to assess for evidence of device-related infection. Results: Homogeneous PET uptake in the LAACD was observed in 93% (26/28) of the PET studies, regardless of the radiotracer used, clinical indication, or time since implantation. Clinical follow-up and laboratory findings revealed no signs of infection related to the LAACD in any case. SUV ratios did not differ significantly between the three PET indication groups (infection, neoplasia, or other; p = 0.46), nor between scans performed in patients with and without other confirmed infections unrelated to the LAACD (p = 0.37). Conclusions: FDG and CHO uptake in LAACDs appears to be a consistent and reproducible finding, most likely reflecting a sterile inflammatory response postoperative inflammatory uptake rather than true infection. Clear recognition of this uptake pattern is important to prevent misinterpretation and reduce the risk of false-positive PET/CT results in patients evaluated for suspected cardiovascular infections.