Latest Watchman Design Appears Safer, More User-Friendly


The latest iteration of the Watchman left atrial appendage (LAA) closure device seems safe and feasible to use in patients with nonvalvular A-fib, according to a study published online September 10, 2015, ahead of print in Catheterization and Cardiovascular Interventions.

Take Home: Latest Watchman Design Appears Safer, More User-Friendly

The fourth-generation Watchman closure device (Boston Scientific) retains a self-expanding nitinol frame but features increased compression, so only 3 sizes are required to cover the spectrum of LAA orifice diameters. With its smoother circumference, the new design is more user-friendly and less traumatic, the authors say. In addition, this model can be fully recaptured and redeployed without complete removal, limiting damage to the frame.

Researchers led by Horst Sievert, MD, of CardioVascular Center Frankfurt (Frankfurt, Germany), prospectively studied 36 patients (mean age 73 years; 67% men) with nonvalvular A-fib who were implanted with the new Watchman device  between February 2010 and June 2011. Mean CHADS2 and CHA2DS2-VASc scores were 2.5 and 4.5, respectively.

Technical success was achieved in 94% of the cohort. In 2 patients, implantation was aborted due to unfavorable anatomy. The 26-mm size was most frequently used (44%), followed by the 31-mm (33%) and the 22-mm (17%) sizes.

Low Adverse Event Rates

Procedural success also was 94%, as there were no procedure- or device-related serious adverse events. Four minor in-hospital complications occurred, including groin hematoma in 3 patients and 1 small pericardial effusion that did not need intervention.

No patients presented with peridevice leak > 5 mm within 1 year after the procedure. Residual flow > 3 mm was seen in 1 patient after 6 months and in 2 patients after 12 months. Device-associated thrombus was observed in 1 patient at 6 months, but it resolved within 4 weeks after treatment with low-molecular-weight heparin and had no clinical consequences..

By 45 days, all patients had discontinued the vitamin K antagonist phenprocoumon, although 3 patients subsequently restarted the drug due to a stroke or TIA.

Three patients died over 12 months—1 of a hemorrhagic stroke followed by multiorgan failure, 1 of a thromboembolic stroke likely due to mitral valve endocarditis, and 1 of a traumatic brain injury. Strokes were reported in 11% of patients at 12 months (1 hemorrhagic and 3 ischemic). In 2 patients with ischemic stroke, symptoms resolved entirely in the hospital, although the etiologies of these strokes remain unknown. In addition, 1 patient experienced a TIA.

Stroke rates in this population were slightly higher than those seen in the PROTECT AF and PREVAIL trials, but there were no instances of serious pericardial effusion or device embolization (table 1).

Table 1. Stroke and Death Rates in Comparison to the PROTECT AF and PREVAIL Trials

The high technical and procedural success rates prove the feasibility and acute safety of the new device,” Dr. Sievert and colleagues say.

Its technical innovations seem to improve safety, they say. “Serious in-hospital adverse events were completely avoided and no relevant pericardial effusion could be detected,” even though 22 patients required partial or full recapture, which implies that there was significant manipulation of the device. The authors also note that in the initial European experience of the Amplatzer Cardiac Plug (St. Jude Medical), the incidence of cardiac tamponade or pericardial effusion requiring intervention or surgery was 3.5%.

Additionally, they write, the updated distal end of the device is “less traumatic,” potentially reducing the risk of pericardial effusion. Moreover,  the design’s enhanced compression “allows for a wider range of LAA dimensions to fit one occluder size. This [allows] larger deviations with regard to proper LAA sizing.”

This is important because 2-dimensional TEE tends to underestimate the LAA orifice and improper sizing “may lead to incomplete LAA sealing and peridevice flow as well as device embolization,” the authors explain. Also, if full recapture of the occluder is necessary, this new device can be reused, saving cost and procedural time compared to older iterations.

Robert J. Sommer, MD, of Columbia University Medical Center (New York, NY), told TCTMD in an email that the modifications made for the fourth-generation device should improve safety and expand the pool of patients eligible for LAA closure, noting that the first-generation device is still being used in the United States.

“The rounded leading edge [of the newest iteration] should definitely reduce perforations and effusions,” he said. “The current device is shallower than the one we use in the United States, which makes more LAAs candidates to receive the device (the smaller depths in some precluded implant of the first-generation device). Finally, the ability to redeploy will make it easier to reposition the device safely if necessary.”

Dr. Sommer said it is unclear why the stroke rate is higher, adding that it “could simply be a sampling error in a small population.”


Source: 
Ledwoch J, Franke J, Gonzaga M, et al. Left atrial appendage closure: first in man with the 4th generation Watchman device. Catheter Cardiovasc Interv. 2015;Epub ahead of print.

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Disclosures
  • Dr. Sievert reports receiving institutional grant support and stock options from numerous pharmaceutical and device companies.
  • Dr. Sommer reports serving as a principal investigator for the PREVAIL trial.

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