Author + information
- Dongming Hou1,2,
- Elena Ladich2,
- Brian Tischler1,
- Alex Pflugfelder1,
- Barbara Huibregtse1 and
- Renu Virmani2
The WATCHMAN FLX (WM FLX) is the next generation WATCHMAN (WM) device with improved deliverability and conformability resulting in a better seal. Two phases of comparative studies of WM FLX versus WM were conducted to evaluate device performance and biologic healing response in a canine model at 45 and 90 days.
Under TEE and x-ray guidance, the device was sized at the LAA ostium. Device implant success was evaluated. 100% of WM FLX canines (6/6) and 75% of WM canines (6/8, one each was excluded from the study due to pericardial effusion or unfavorable anatomy) were successfully deployed. All devices were positioned within the LAA appropriately with conformation to variable left atrial anatomy (Table). For healing response evaluation, half of each group survived to 45d and half to 90d, respectively, before termination.
Histologically, there was no gross or microscopic evidence of myocardial infarction, and no compression of the underlying LCx artery. The WM FLX showed a similar biologic healing response when compared to WM at 45d and 90d. Endocardial tissue growth was complete to near complete in all devices with the exception of single animal from the WM group at 90d in which there was minimal thrombus associated with slight protrusion of the device into the left atrium. Inflammation was minimal in all devices and consisted of chronic inflammation with rare multinucleated giant cells localized near the polyester cover.
The next generation of WM FLX showed an improvement in deliverability with fewer device partial and full recaptures, and a better seal with lower incidence of observed peri-device jets, though neither device showed residual peri-device jets in excess of 2 mm (peri-device jet <5mm is deemed acceptable per Directions for Use). Both devices were evaluated as safe, and healing by endothelialized endocardial tissue growth was essentially complete by 90d in both WM FLX and WM with histologic features similar to those previously reported for WM and other larger cardiac devices.