Page 14 - Journal of Structural Heart Disease Volume 2, Issue 1

Review Article
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on a mean CHADS2 score of 2.8 was 7.3% per year. This demonstrated an association with significant event rate reduction. Of note, laminar thrombus formation has been reported with the WATCHMAN device. The ASAP trial had six cases of thrombus formation (4%) on the device with only one resul- tant clinical event (ischemic stroke). This was sim- ilar to PROTECT AF, which had a 4.2% (20 of 473) thrombus formation rate with three having isch- emic strokes. The thrombus-associated annualized stroke rate was 0.3%. While ASAP was a prospective, observational trial, the totality of data involving the WATCHMAN device remains critical to estab- lishing the LAA as focal source of thromboembolus and that closure of the LAA decreases stroke rate. Data from various studies support WATCHMAN as an alternative to anticoagulation in both warfarin eligible and warfarin ineligible patients.
Lariat
The Lariat device (SentreHeart, Redwood City, Cal- ifornia, USA) is a transcatheter LAA ligation system that utilizes both endocardial and epicardial ap- proach to place a preformed surgical knot around the ostium of the LAA and approximate all walls thus excluding the LAA [49]. Epicardial access (“dry tap”) is performed through a subxyphoid approach with a micropuncture needle or 17-gauge epidural needle. Access is obtained in the anterior aspect of the peri- cardial sac with angulation toward the LAA. Dilation up to a 14 French sheath is required. The 14 French epicardial sheath is placed over a sti guidewire. Femoral venous access is obtained and a transsep- tal puncture is performed to gain left atrial access. A magnet tip wire is then placed in the LAA endocardi- ally. An epicardial magnet wire is advanced into the pericardial space toward the LAA until a connection is made between the endo- and epi-magnet wires. The Lariat loop snare is then carefully advanced over the epicardial wire while holding the wires in place until the device is placed over the LAA and closed (Figure 5). TEE guidance is utilized to visualize LAA closure and assess adequacy of closure. A preformed surgical knot is deployed. A tensioner is used to tight- en the knot before cutting the suture. The procedure
is limited to patients with LAA less than 40 mm due to loop snare size. Unfavorable orientation of the ap- pendage determined on the required preoperative CT may exclude the patient from this procedure. It is also limited to patients who have not had previous cardiac surgery. The device currently has FDA 510k approval for tissue approximation. While initial data has demonstrated a high rate of success in terms of closure and leaks, most studies have been small, ob- servational studies. Bartus et al. [49] prospectively enrolled 92 patients who were not warfarin eligible or were poor candidates for warfarin. Presence of pericardial adhesions excluded three patients. The remaining 89 patients underwent attempted Lariat closure of the LAA. Successful closure (< 1 mm resid- ual leak) was performed in 96% of the patients. Of patients undergoing TEE at one year, 98% (64 of 65) had complete closure. Complications occurred in ve patients with three having pericardial e usions and two having pericarditis. An additional patient devel- oped a late e usion, 2 weeks after LAA closure. More recently, Price et al. [50] retrospectively evaluated the results of Lariat procedures in 154 patients at eight di erent centers. While procedural success was high (86%), major complications occurred in 15 patients (9.7%). Signi cant pericardial e usion occurred in 16 patients (10.4%). There were 14 (9.1%) major bleeds with 4.5% of all patients needing transfusion. Death, myocardial infarction, or stroke occurred in 4 patients (2.9%). Thrombus formation at the endocardial site of LAA closure has also been reported [51, 52]. Given the limited data, a large, randomized, controlled trial is needed not only to con rm the apparent high pro- cedural success but also better understand the clini- cal e cacy of the procedure as well as the procedural risks involved with this technique.
Wavecrest
The Wavecrest LAA occluder device (Coherex Med- ical, Salt Lake City, Utah, USA) is an umbrella shaped device designed to cover the LAA at the ostium. It is constructed with a nitinol frame and covering mate- rial with anchoring barbs which are deployed after the covering face is rst positioned into place at the osmium (Figure 6). The covering material consists of nonpermeable, Te on material at the face and a foam
Journal of Structural Heart Disease, February 2016
Volume 2, Issue 1:1-14