Atrial fibrillation is associated with an increase in the risk for stroke.1,2 The left atrial appendage (LAA) has been implicated in the formation of clots in patients with atrial fibrillation, with numbers as high as 90% of all clots in the heart found in the LAA.2 There have been several retrospective and prospective trials that have assessed the efficacy of removal of the LAA for decreasing the risk of postoperative stroke.3–7 In one retrospective article of 205 patients undergoing mitral valve replacement, there were significantly fewer strokes in patients who had LAA removal.6 In addition, the Left Atrial Appendage Occlusion Study is underway, which is a randomized control trial looking at whether LAA ligation will decrease the incidence of cerebral-vascular accident in high-risk coronary artery bypass graft. Pilot data from the Left Atrial Appendage Occlusion Study showed fewer strokes with ligation but did not reach statistical significance.7
It is important to ascertain whether LAA occlusion is not only effective at preventing strokes but also safe. There has been conflicting evidence regarding the safety of performing this procedure. A retrospective study done by Katz et al8 showed that in 50 patients undergoing mitral valve replacement and LAA ligation, 32 had successful closure as seen by echocardiography. Of those who did not have successful closure, four patients developed clinically significant embolic strokes.8 A case series done by Schneider et al9 showed that in patients with incorrectly ligated LAAs, there was a 17% incidence of stroke, which is significantly higher than in the general population. In their best evidence article on LAA exclusion for patients undergoing cardiac surgery with atrial fibrillation, Dawson et al10 discussed that the results of previous studies do not show a clear benefit for LAA occlusion. Using Medline for their search, they reviewed articles from 1950 to 2009. They found 12 of 310 papers written on the topic could be used to address their question about whether occlusion of the LAA during cardiac surgery for patients with atrial afibrillation is beneficial. They found that the success rate regardless of method of closure (stapling, ligation, or amputation) ranged between 55% and 93%. One study actually found that there was increased risk for a thromboembolic event. Based on these findings, they concluded there was insufficient evidence to support LAA occlusion in patients with atrial fibrillation undergoing cardiac surgery.10
In their retrospective study, Kanderian et al11 found that only 23% of the patients with suture exclusion had a successful LAA closure. Furthermore, with the advent of a new atrial appendage clip, the necessity of suturing or surgical excision of the atrial appendage may no longer be relevant in the near future. In 2010, Salzberg and colleagues12 reported the successful closure of the LAA in a series of 34 patients who were elective cardiac surgery patients who presented for atrial fibrillation ablation. At 3 months (n = 30), they found no strokes or transient ischemic attacks. And all LAAs were successfully excluded.12 Ailawadi et al5 recently reported their findings when using the AtriClip device to exclude the LAA in patients undergoing elective cardiac surgery through a median sternotomy with atrial fibrillation or had a CHADS score greater than 2. For the CHADS score one point is given for each of the following conditions: congestive heart failure (C), hypertension (H), age 75 years old or greater (A), diabetes mellitus (D), and stroke (S), which receives 2 points. A CHADS score of 2 or greater is an indication for a patient to be placed on anticoagulation. The results of this multicenter study (n = 70) showed that 95% of the LAAs were successfully excluded as shown by either computed tomography angiography or transesphogeal echocardiography at 3 months.5
We recently undertook a study to determine which method of LAA occlusion was considered safe. Patients referred for nonemergent CABG and/or cardiac valve replacement surgery who also presented with one or more of the following risk factors for postoperative atrial fibrillation and/or stroke were recruited: age older than 65 years and with either additive Euroscore higher than 6, hypertension, history of myocardial infarction, or previous CVA. One patient who had his/her LAA excluded by suture was found to have a small jet flow through his/her LAA area. No patient who underwent exclusion with excision or suture of the LAA had a stroke during hospitalization or at the 6-week checkup. We stopped this study early because we felt we had established our end point of safety and could no longer justify enrolling more patients into the study.
Therefore, at this point, we do not advocate for suture exclusion of the LAA as a method to decrease the incidence of stroke in patients at high risk for the development of atrial fibrillation and, consequently, a stroke after cardiac surgery. We will look forward to the results of the LAAOS trial as well as the continual reporting of the new LAA clip.
1. Go A, Hylek E, Phillips K, et al.. Prevalence of diagnosed atrial fibrillation in adults: national implications for rhythm management and stroke prevention: the Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) study. JAMA. 2001; 285: 2370–2375.
2. Chugh S, Blackshear J, Shen WK, et al.. Epidemiology and natural history of atrial fibrillation: clinical implications. J Am Coll Cardiol. 2001; 37: 371–378.
3. Garcia-Fernandez MA, Pérez-David E, Quiles J, et al.. Role of left atrial appendage obliteration in stroke reduction in patients with mitral valve prosthesis: a transesophageal echocardiographic study. J Am Coll Cardiol. 2003; 42: 1253–1258.
4. Blackshear JL, Odell JA. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. Ann Thoracic Surg. 1996; 61: 755–759.
5. Ailawadi G, Gerdish M, Harvey R, et al.. Exclusion of the left atrial appendage with a novel device: early results of a multicenter trial. J Thorac Cardiovasc Surg. 2011; 142: 1002–1009.
6. Killip T, Passamani E, Davis K. Coronary Artery Surgery Study (CASS): a randomized controlled trial of coronary surgery. Eight years follow-up in patients with reduced ejection fraction. Circulation. 1985; 72: 102–109.
7. Healey JS, Crystal E, Lamy A, et al.. Left Atrial Appendage Occlusion Study (LAAOS): results of a randomized controlled pilot study of left atrial appendage occlusion during coronary bypass surgery in patients at risk for stroke. Am Heart J. 2005; 150: 288–293.
8. Katz ES, Tsiamtsiouris T, Applebaum RM, et al.. Surgical left atrial appendage ligation is frequently incomplete: a transesophageal study. J Am Coll Cardiol. 2000; 36: 468–471.
9. Schneider B, Stollberger C, Sievers HH. Surgical closure of the left atrial appendage—a beneficial procedure? Cardiology. 2005; 104: 127–132.
10. Dawson AG, Asopa S, Dunning J. Should patients undergoing cardiac surgery with atrial fibrillation have a left atrial appendage exclusion? Interact Cardiovasc Thorac Surg. 2010; 10: 306–311.
11. Kanderian AS, Gillinov AM, Pettersson GB, et al.. Success of surgical left atrial appendage closure—assessment by transesophageal echocardiography. J Am Coll Cardiol. 2008; 52: 924–929.
12. Salzberg S, Plass A, Emmert M, et al.. Left atrial appendage clip occlusion: early clinical results. J Thorac Cardiovasc Surg. 2010; 139: 1269–1274.