Append Medical, with their novel left atrial appendage (LAA) closure device (Appligator), were a finalist in the 2019 ICI Innovation Award Competition (Innovation in Cardiovascular Interventions 2019; 8–10 December, Tel Aviv, Israel). In this commentary, Leonid Sternik who came up with the concept for the device, outlines the need for LAA closure in the context of atrial fibrillation and how the Appligator could address current challenges with existing devices.
The LAA is a place of blood clot formation and source of emboli in patients with atrial fibrillation. It is the most frequent arrhythmia, occurring in 2% of population overall and in 5–10% of those aged older than 70 years. The rate of embolic stroke in atrial fibrillation patients is four to 17 times higher than in people of the same age without atrial fibrillation. Embolic stroke is a devastating complication with a very high morbidity, mortality and cost of treatment. To prevent blood clot formation in the LAA and embolic stroke, many patients need to take anticoagulation. Of note, warfarin is associated with significant complications in 1–2% per patient per year.
Given the high incidence of LAA clot formation and the lack of any efficient technique for preventing clot formation, there are several devices and methods for LAA obliteration. Surgical methods include amputation of the appendage, “over sewing” from the atrial side, and ligation of the appendage from the epicardial side. The appendage can also be closed by clip from the epicardial side. However, these methods are associated with serious disadvantages—both amputation of the appendage (and sewing the stump) and sewing from the atrial side are time consuming and are associated with a risk of bleeding; amputation, ligation, and clipping the LAA all leave a residual pocket (with a resultant remaining risk for clot formation), sewing from the atrial side is associated with a higher percentage of recanalisation, and clipping the LAA from the outside is expensive.
Transcatheter occluders, including Watchman (Boston Scientific) and Amplatzer (Abbott), have been shown to reduce the risk of stroke. However, they also have some serious disadvantages: they are foreign bodies of a relatively big size, and dislocation and embolisation of the devices have been reported; “sharp hooks” are employed to hold them in place, which is associated with a risk of perforation of atrial wall with subsequent hemopericardium and tamponade; and anticoagulation may be needed until endothelisation of the occluder surface. Also, the size and the shape of the LAA differs amongst patients, so occluders must be of different size to fit the appendage—this means that transcatheter LAA closure is operator dependent, which make it prone to a learning curve and misjudgement.
We have designed a transcatheter device to safely obliterate LAA that does not use sharp hooks to place the device and that, after the procedure, only leaves a minimal amount of foreign material behind. Our goal with the device is that it will reduce the risk of complications and reduce procedure times. The idea of this invention is that the invaginated LAA will remain in its position after LAA Intra-atrial suturless cosure and will not cause damage to the heart because:
- The use of silk thread will avoid damage to the LAA.
- Tying LAA outside the heart has been safely done for more than 50 years.
- The invaginated LAA is relatively small (in comparison to heart myxomas) and will not affect blood flow in the heart (blood flow is affected only by large myxomas >70gr).
- The LAA tissue is covered with endocardial cells that avoid thrombolytic effect.
Leonid Sternik is at the Department of Cardiac Surgery, Sheba Medical Center, Ramat Gan, Israel.