Brief Introduction

Atrial fibrillation is the most common and most treated cardiac arrhythmia in clinical practice. It is associated with 5-fold increase in the incidence of stroke and increasing risk with ages [1]. The consequences are very serious. Compared with non-AF-related stroke, the recurrence rate is increased by 61% [2], the disability is increased by 74% [3] and the mortality is increased by 119% [4]. As reported, about 91%of thrombi were originated in the left atrial appendage in patients with non-valvular heart disease; about 57% of thrombi were present in the left atrial appendage in patients with valvular heart disease【5】.

Even after restoration of sinus rhythm, if the LAA contraction is compromised, there is still the possibility of thrombosis. Current clinical prevention methods of ischemic stroke for AF patients include as follows: one method is to take anticoagulant drugs, such as warfarin, but the patient would take a certain risk of bleeding. The INR should be frequently monitored. It has more contraindications, so the clinical application is difficult. In addition, warfarin may cause osteoporosis and soft tissue necrosis. The second method is excising the LAA simultaneously with cardiac surgery. The main issue is the low exclusion rate of the LAA. Although previous studies have shown that the successful exclusion rate is as high as 80% during surgery [4], postoperative research has demonstrated very low exclusion rate at 50%, under TEE evaluation [5]. The third method is utilizing a medical device to close the LAA. It has 2 approaches: one is endocardial occlusion, while the other is epicardial exclusion. Endocardial occlusion through percutaneous intervention needs atrial septal puncture, which is very complicated. And, it is easy to lead to device-related complications. Postoperative residual leakage is up to 32% [6], device-related thrombosis is up to 7% [7], and continued anticoagulation after surgery is necessary.

Med-Zenith provides a new approach for LAA exclusion. The LAA Clip could be implanted through either thoracoscopic or thoracic surgery. It is to be placed on the root of the LAA and mechanically close the LAA through an epicardial approach.  This approach is simple, safe and effective. Postoperative follow-up has shown 100% exclusion rate [8], without residual leakage, thrombosis, and any other complications.

Figure 1: LAA exclusion

Figure 2: Layered Thrombus Formation on the Device

References:

【1】Wolf PA, et al. Atrial fibrillation as an independent risk factor for stroke: the Framingham Study. Stroke. 1991; 22: 983-8.

【2】Mohan KM, et al. Frequency and Predictors for the Risk of Stroke Recurrence up to 10 years after stroke: The South London Stroke Register. J Neurol Neurosurg Psychiatry. 2009; 80 (9): 1012-8.

【3】McGrath ER, et al. Association of atrial fibrillation with mortality and disability after ischemic stroke. Neurology. 2013;81(9):825-32.

【4】Saposnik G, et al. Atrial Fibrillation in Ischemic Stroke Predicting Response to Thrombolysis and Clinical Outcomes. Stroke. 2013; 44(1): 99-104.

【5】Blackshear JL, et al. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. Ann Thorac Surg. 1996; 61(2): 755-9.

【6】Onalan O, et al. Left atrial appendage exclusion for stroke prevention in patients with nonrheumatic atrial fibrillation. Stroke. 2007; 38: 624-30.

【7】Kanderian AS, et al. Success of surgical left atrial appendage closure: assessment by transesophageal echocardiography. J Am Coll Cardiol. 2008; 52(11): 924-9.

【8】Viles-Gonzalez JF, et al. The clinical impact of incomplete left atrial appendage closure with the Watchman Device in patients with atrial fibrillation: a PROTECT AF (Percutaneous Closure of the Left Atrial Appendage Versus Warfarin Therapy for Prevention of Stroke in Patients With Atrial Fibrillation) substudy. J Am Coll Cardiol. 2012; 59 (10): 923-9. 

【9】Sick PB, et al. Initial worldwide experience with the WATCHMAN left atrial appendage system for stroke prevention in atrial fibrillation. J Am Coll Cardiol. 2007; 49(13): 1490-5.

【10】Data on file.