Left Atrial Appendage Exclusion Device for Protection From Thromboemboli

Abstract & Commentary

By John P. DiMarco, MD, PhD, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville.

Source: Bartus K, et al. Percutaneous left atrial appendage suture ligation using the LARIAT device in patients with atrial fibrillation: Initial clinical experience. J Am Coll Cardiol 2012; Sept. 28. [Epub ahead of print.]

The left atrial appendage is thought to be the source of a large proportion of emboli in patients with nonvalvular atrial fibrillation. In this paper, Bartus and his colleagues describe an innovative new device that uses a combined transseptal-epicardial approach to ligate the left atrial appendage. The LARIAT system requires both epicardial and transseptal access. First, an epicardial puncture is made and an introducing sheath is inserted into the pericardium. A transseptal puncture is then made and a delivery catheter placed in the left atrial appendage. A wire with a magnet on the tip is placed in the left atrial appendage and used to attract and establish contact with a second magnet introduced into the epicardial space. A balloon is inflated in the left atrial appendage to define the ostium and then a suture is advanced via the pericardium over the wires that are joined by the magnets and over the balloon. Once satisfactorily positioned, the suture can be closed and the transseptal catheter removed. Finally, the suture is cut and the epicardial introducer system is removed. A pericardial drain is typically left in place for a short time. The entire procedure is guided by combined transesophageal echocardiograpy and fluoroscopy.

In this initial human report, the authors report on results in 89 patients enrolled between December 2009 and December 2010. All patients had nonvalvular atrial fibrillation and a CHADS2 score ≥ 1. Patients with a history of pericarditis, cardiac surgery, recent embolic events or myocardial infarctions, and unfavorable chest anatomy were excluded. Prior to randomization, patients underwent a screening contrast CT scan, and patients with markedly enlarged or unusually oriented left atrial appendages were also excluded. After the procedure, patients underwent transesophageal echocardiography at 1 day, 30 days, 90 days, and 1 year post procedure to assess for complete closure. Warfarin was continued at the discretion of the patient’s physician.

A total of 119 patients were screened for the procedure and 103 were thought to be eligible. On the day of the procedure, three patients were found to have adhesions and 11 patients were found to have mobile thrombi in the left atrial appendage and were excluded. Therefore, the final study group included 89 patients. Successful left atrial appendage closure was accomplished using the LARIAT system in 85 of these 89 patients (95.5%). Complete closure of the left atrial appendage was documented in all but two of these patients at follow-up. During the procedure, a single pericardial access was required in 68 of 85 patients, and in an additional 17 patients, a second pericardial access was required to obtain proper sheath orientation for delivery of the LARIAT snare. The mean time to connect the transseptal and the epicardial magnets was 1.4 ± 0.64 minutes. Transesophageal echo guidance resulted in proper position of the LARIAT snare and the ostium of the appendage in all patients. Mild chest pain was reported postoperatively by 20 of 85 patients. Only two of these, however, required treatment for pericarditis after removal of the pigtail drain in the pericardium. One other patient developed a late pericardial effusion 2 weeks after the procedure. This was treated with pericardiocentesis and the patient recovered without further complications. During long-term follow-up, there was one sudden cardiac death and one hemorrhagic stroke. The latter patient was not on warfarin. At the 1-year follow-up, there were two additional adverse events. One patient with severe bradycardia who had refused pacemaker implantation died suddenly. One patient had a lacunar stroke.

The authors conclude that left atrial appendage occlusion with the LARIAT system provides a rapid and effective way for complete closure of the left atrial appendage. Further trials are required to see if this reliably prevents thromboembolic events in patients with atrial fibrillation.

Commentary

Most studies have estimated that 85-90% of emboli in patients with nonvalvular atrial fibrillation arise in the left atrial appendage. Long-term oral anticoagulation has a high rate of minor and major bleeding, even with the newer oral anticoagulants. For this reason, a number of novel approaches for completely occluding the left atrial appendage are now being developed. Some recently designed surgical clips appear to be much more effective than older stapling or suture techniques, but require at least thoracoscopic access to the left chest. Several devices for occluding the left atrial appendage from a transseptal approach are undergoing trials and the Watchman device is fully released in some European countries. Endocardial devices, however, have barbs that are used to fix the device in position, but then can come loose and cause bleeding. The LARIAT system ligates the appendage from an epicardial approach and may prove safer. The preliminary data shown in this paper are quite impressive. However, we must note that one shouldn’t conclude that this technique is superior or even non-inferior to oral anticoagulation until appropriate trials in which safety and stroke are the primary endpoints have been completed. The preliminary data presented here are very impressive and we can hope that the appropriate trials will soon be underway.