Surgical Closure of the Left Atrial Appendage . Basal Considerations before attempting with Occluder Devices

Despite a lot of publications in favor of left atrial appendage occlusion, basal considerations regarding the closure of the left atrial appendage seem to be missed. Surgical closure of the left atrial appendage is the most direct method to analyze all the most common arising contingencies. The most effective method to achieve a successful left atrial appendage closure is surgical “cut-and-sew” with total removal of the left atrial appendage. Surgical suture exclusion and stapler exclusion show 23% and 0% of success rate, respectively. A high percentage of patients with suture exclusion have persistent flow into the appendage documented by color Doppler (60%), and a high percentage of those with stapler exclusion exhibit a persistent left atrial appendage stump >1 cm (58%). Incomplete closure of the left atrial appendage is an independent predictor of stroke or systemic embolism, and the stroke risk is 5-fold higher than expected. All these data may have important implications for cardiologists regarding left atrial appendages occluder devices.


Sci Forschen
O p e n H U B f o r S c i e n t i f i c R e s e a r c h

Journal of Surgery: Access Open Access
There is a large amount of material available in the literature regarding left atrial appendage (LAA) as the main emboli gen source of the heart in patients having any type of atrial fibrillation (AF).In fact, 91% of the thrombin patients with non-rheumatic AF and 57% with rheumatic AF arise from the left atrial appendage [1].It has been suggested the prophylactic LAA removal whenever the chest is open in order to prevent future strokes [2].Current 2016 guidelines for treatment of AF point out that surgical occlusion or exclusion of the LAA may be considered for stroke prevention in patients with AF undergoing cardiac surgery.In addition, the authors stated that residual LAA flow or incomplete LAA exclusion can increase stroke risk [3].
Prior to the issue of the LAA occluder devices, special attention must be paid in LAA surgical exclusion.The first question is what method is the best one to get success.Several surgical techniques have been used in order to exclude the LAA.There are two basic techniques: exclusion and removal, each one of them with some variations.Kanderian et al. [4] studied 137 patients underwent surgical LAA closure with transesophageal echocardiography after surgery.Thirty-eight percent underwent excision, either by scissors or an amputating stapling device; and 62% underwent exclusion (inner suture or external stapler leaving LAA in situ).The most effective method to achieve success was the excision showing 73% of success rate, followed by suture exclusion (23%), and stapler exclusion (0%).However, as a whole group, only 40% for successful LAA closure was obtained.What does it mean?The most effective method to achieve a successful LAA closure is surgical "cut-and-sew" with total removal of the LAA.Moreover, looking carefully for the error sources in the group of surgical excision, remnant LAA causes 27% for failure.Remnant LAA is defined as a residual stump or pouch remaining in the LAA >1 cm in maximum length after closure.Surrounding area of the LAA base is friable and thin with fat pad containing the circumflex coronary artery.Several extremely thin areas of atrial wall are located at the base of the ISSN 2470-0991 LAA [5].Fears of heart disruption, difficult exposure from outside of the heart are some of the most dreaded complications by a cardiac surgeon.A good surgical exposure is usually obtained by adequate selection of the approach.Garcia-Villarreal has described a hands-free approach for LAA in order to avoid all these complications [6].
On the other hand, exclusion of the LAA is performed by closing the orifice into the LA cavity while remaining attached to this one.This technique is performed by various methods of suturing (running suture, purse string or external ligation) or by stapling.Although these surgical techniques are simple to apply, there is uncertainty regarding their reproducibility and effectiveness.In the article by Kanderian et al. [1], 5.8% showed patent LAA (excision, 0%; suture exclusion, 8%; stapler exclusion, 17%), remnant LAA, 20% (excision, 27%; suture exclusion, 8%; stapler exclusion, 58%), excluded LAA with persistent flow, 34% (excision, 0%; suture exclusion, 61%; stapler exclusion, 25%), and a successful LAA closure, 40% (excision, 73%; suture exclusion 23%; stapler exclusion, 0%).Noteworthy, a high percentage of patients with suture exclusion of the LAA had persistent flow into the appendage documented by color Doppler from the LA and the LAA (60%), and a high percentage of those with stapler exclusion had a persistent LAA stump >1 cm (58%).LAA partially closed is more likely to thrombose because of higher blood stasis.In fact, the prevalence of LAA thrombus in appendages with the persistent flow was high in this study (46% in suture exclusion and 67% in stapler exclusion).Such a summary, therefore, has important implications for both cardiologists and surgeons.For the less-invasive procedures in which most surgeons are likely to use either suture or stapler for LAA exclusion, this study presents clear evidence of the inadequacy of these techniques.The only safe method to achieve a complete surgical closure of the LAA is excision (with scissors or stapler).The other ones need to be reviewed, improved and maybe avoided.Similar results have found by Schneider et al. [7].They studied 6 consecutive patients with paroxysmal (n=3) or permanent (n=3) atrial fibrillation who underwent surgical LAA closure at the time of valve surgery.At a large follow-up (mean 51 months), complete LAA closure was observed in only 1 patient.Five incomplete LAA closures were found due to disruption of the closure line.The spontaneous echocardiographic contrast in the LAA had newly developed (n=3) or was much more intense than preoperatively (n=2), resulting in blood stagnation and an increased likelihood of clot formation.Incomplete surgical LAA closure may promote rather than reduce the risk of stroke.Indeed, incomplete closure of the LAA is an independent predictor of stroke or systemic embolism in univariate analyses.Aryana et al. [8] have studied the association between incomplete surgical ligation of LAA and stroke/systemic embolization.In this study on 72 patients, those with stroke and systemic embolization and incomplete surgical ligation of the LAA exhibited a significantly smaller neck diameter (2.8 ± 1.0 vs 7.1 ± 2.1 mm; P=0.002).In this setting, the annualized stroke and systemic embolization risk were 6.5%, increasing up to 14.4% while not receiving oral anticoagulation, and 19.0% in those cases with neck diameter ≤5.0 mm, per 100 patient-years of follow-up.Stroke risk was 5-fold higher than expected.
Mild periprosthetic leakage after LAA closure with catheter-based techniques has been observed up to 16.2% in a 6-month follow-up by transesophageal echocardiography [9].Despite the fact that several studies have suggested the benign course of this complication [10][11][12], because of the short-term duration of these studies, there is a lack of evidence about the real long-term impact.Long-term follow-up is mandatory to properly validate the effect of peri-device leakage after LAA closure with occluder devices.
All these considerations play an important role in the field of LAA occlusion or exclusion.At the same time, it acts as a starting point for future studies and specifically to open debate on the conditions and requirements focused on LAA occluder devices.