Chronic atrial fibrillation (AF) increases the risk of stroke by a factor of five, and is responsible for 15% of all strokes. The current standard of care to prevent strokes in AF patients is a lifetime of oral anti-coagulation (OAC) therapy, which is associated with many side effects including major gastro-intestinal and intra-cranial bleeding.
Further, patients taking OAC therapy must eliminate activities that increase the risk of injury due to the risk of uncontrollable bleeding.
Further complicating the effectiveness of OAC therapy, many patients prescribed OAC therapy are found to not have therapeutic levels of the blood thinner to actually reduce risk of stroke. The primary source of thrombin, or clots, in patients with AF is in a heart “chamber” known as the left atrial appendage.
An alternative to lifelong OAC therapy is to occlude this appendage, preventing existing clots from entering the bloodstream and preventing future clots from forming. Existing alternatives to OAC therapy – known as ‘left atrial appendage closure’ (LAAC) devices and techniques – exist to occlude the appendage, allowing AF patients to terminate OAC therapy without increasing the risk of often devastating stroke.
Many studies have shown that placement of an LAAC device and terminating OAC therapy can be achieved without significantly increasing the risk of stroke relative to maintaining OAC therapy. However, improper sizing or placement of the LAAC implant results in incomplete occlusion of the appendage in 30-40% of cases. In these cases, despite having undergone the surgical procedure, the patients and treating physicians must decide if the appendage is sufficiently occluded to safely terminate OAC therapy. Exposed metal on existing LAAC technology has been shown to be pro-thrombotic (device-related thrombus, or clots that can cause stroke) in 2-3% of cases. There is also a risk – of up to 10% – of serious complications associated with the implant procedure, such as pericardial effusions and cardiac tamponade resulting from the stiff nitinol frame being pushed through the atrial wall. More consistent, complete occlusion of the appendage, reducing/eliminating device-related thrombus, and safer implant procedures remain key areas of improvement over existing LAAC technology.