Left Atrial Appendage Management: No Better Time Than the Present

Abstract

Stroke remains the most devastating complication in patients with atrial fibrillation (AF). Indeed, the stroke rate for these patients is 5% per year, and 35% of patients with AF will experience a stroke over the course of their lifetime. The left atrial appendage (LAA) is known to be the source of over 90% of cardiac thromboemboli and stroke, and therefore, it has become the focus for primary stroke prevention in patients with AF.1–3 In the absence of persistently effective antiarrhythmic drugs, medical therapy has revolved around the use of oral anticoagulants, balancing the risk between catastrophic bleeding and thromboembolism to decrease stroke, not to mention the adverse effect on quality of life. Additionally, numerous methods have been described to mechanically exclude the LAA in patients with AF. However, it is important to understand what constitutes a successfully excluded appendage. Failure of complete exclusion is considered when there is residual flow in an appendage that has been closed by a percutaneous or surgical method or when there is a remnant endocardial pouch of 1 cm or greater in depth or there is exposed endocardial trabeculae. The advances in technology and technique have expanded the options to treat these patients who are at risk for thromboembolic events. Percutaneous devices such as the FDA approved Watchman (Boston Scientific, Marlborough, MA, United States) has demonstrated effectiveness in reducing stroke in AF. While this device is attractive because of its less invasiveness, it is not a panacea for stroke in AF and the results have to be understood with caution. PROTECTAF (Watchman Left Atrial Appendage System for Embolic Protection in Patients With Atrial Fibrillation), a prospective 2:1 randomized trial of 707 patients, demonstrated noninferiority of the device compared to warfarin; however, proceduralrelated complications were significant at 12%. The PREVAIL (Watchman LAA Closure Device in Patients With Atrial Fibrillation vs. LongTerm Warfarin Therapy) randomized trial of 407 patients failed to show noninferiority of the Watchman device but did show a low procedural complication rate of 2.2%. Ultimately, a metaanalysis including these 2 trials demonstrated that the Watchman device was noninferior for allcause stroke and embolization; however, there was a higher rate of ischemic stroke for patients who received a Watchman. Ischemic strokes were similar once the proceduralrelated strokes were excluded, and there was a lower incidence of hemorrhagic strokes compared to warfarin. Anticoagulation is required postprocedure with warfarin for 45 days and dual antiplatelet therapy for 6 months.4–6 Success is reported to be 93% to 99%; however, this accepts a residual orifice leak of 5 mm or less. Surprisingly, peridevice flow (Fig. 1) or incomplete endothelization frequently occurs and has been reported as high as 32% to 61% and the longterm significance of this is unknown.7,8 Furthermore, certain LAA morphologies as well as an absolute contraindication to anticoagulation such as a hemorrhagic stroke would preclude device implantation therefore leaving a group of patients unprotected. The surgical exclusion of the LAA has been shown to reduce both early perioperative as well as longterm stroke.9 In addition, several series have found a survival benefit due to LAA exclusion at the time of cardiac surgery. In a metaanalysis by Tsai, there was a significant survival advantage in patients who had a surgically eliminated LAA even without an ablation procedure when compared to patients with AF in which the LAA was left intact.10,11 Surgical societies are addressing the importance of LAA exclusion with this growing evidence. In fact, the most recent 2017 STS guidelines