Targeting the left atrial appendage for AF-related stroke prevention: Why the heart team is necessary

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Sasha Salzberg

Sacha Salzberg cardiovascular surgeon (Heart Clinic Hirslanden, Cardiac Surgery Unit, Zurich, Switzerland) comments on catheter-based and surgical approaches for left atrial appendage occlusion as treatment strategies for stroke prevention in atrial fibrillation (AF) patients. He calls for a heart team approach to best manage these patients.     

 

By Sacha Salzberg

It is in the setting of atrial fibrillation that the left atrial appendage (LAA) plays its crucial negative role as origin for stroke, and it is known that 90% of strokes originate inside the LAA. 

Currently, the gold standard treatment for stroke prevention in AF patients with a CHA2DS2-VASC score >1 is oral anticoagulation. However, this type of treatment comes with serious side effects due to its relative unpredictability and unattractiveness in this patient population. New pharmacologic agents are currently available and have already been integrated into the newest guidelines, but have yet to become the perfect solution. Therefore, the most recent guidelines by the European Society of Cardiology (ESC) recommend occlusion of the LAA as a strategy in patients in whom anticoagulation cannot be performed, albeit with a modest weight, as it is a Class IIb with a level of evidence C. LAA closure can be achieved by many different means; however, success and durability are crucial to increase clinical adoption of this novel therapy and to break the anticoagulation paradigm in AF.


Catheter-based approaches for LAA closure

Currently two devices are available and approved for LAA closure Amplatzer (St Jude Medical) and Watchman (Boston Scientific). Initially, a significant morbidity due to procedural-related events was seen in major trials, such as PROTECT AF for the Watchman device. However, with increased experience and further device developments, clinical results are excellent and overall acceptance is steadily growing. PROTECT AF was the first prospective randomised trial comparing LAA catheter occlusion to warfarin. In this trial, not only a significant decrease in haemorrhagic strokes was seen but also an increased survival over time in the device arm was demonstrated when compared to oral anticoagulation in selected patients. The same clinical results are to be expected from its main contender, the Amplatzer device in Europe. Recently, the Lariat Suture Delivery Device (SentreHeart) has become available and been used in a limited number of cases. This device combines a pericardial and transeptal approach to deliver a suture-based solution to the base of the LAA.

None of the above mentioned devices achieve 100% closure in all comers. This is due to the high anatomical variability of the LAA. As the catheter-based approach only deals with occluding the ostium of the LAA, it becomes clear that an epicardial approach addressing the neck of the LAA may provide the solution. This is why other approaches must be considered to achieve perfect results and offer the best clinical outcomes. 

Surgical LAA closure

Surgical management of the LAA should be a standard in any patient with AF undergoing open heart surgery. In addition, in patients with risk factors for AF and/or prior cardiac stroke we recommend LAA occlusion. Strategies for managing the LAA are influenced by the surgical approach and several techniques are available. Generally, sutures can be used, a clip can be applied or a stapler may be used to resect the LAA. In the setting of stand-alone minimally invasive surgery for AF the experience with staplers is vast. Excising the LAA by video assisted thoracoscopic procedure is a straightforward procedure, which can be performed in patients with any form and shape of LAA. Only the safety issues with staplers remain an Achilles heel of this procedure, this is where the new AtriClip LAA Occlusion System (AtriCure) offers the safest results. In this manner, when patients require LAA closure who may not be amenable to a catheter solution due to, for instance, anatomical considerations, a video assisted thoracoscopic procedure can be used to apply the AtriClip to the LAA. Hence, offering a very effective therapy with minimal morbidity and risk.

Whatever option for LAA closure is chosen, it is essential to obtain complete occlusion, ie. close sealing at the base of the LAA as close as possible to the roof of the left atrium. Any “cul de sac” of more than 1.5cm is considered a failed closure and puts patients at increased risk of stroke. In the past, too little attention has been applied by cardiac surgeons when addressing the LAA leading to terrible clinical results and misperception of cardiac surgery potential in this regard.


Summary

When addressing LAA, safe and durable occlusion must be achieved. To get there, either endocardial or epicardial devices are available. It is crucial to use an outcome-based approach. In our experience, this makes the true heart team mandatory. Only in this setting, patients can objectively be discussed and stratified for one treatment or the other. Not only patient specific factors play a role, but also morphological considerations. We should consider that when 100% occlusion cannot be expected by a catheter approach, referral for minimally invasive surgical LAA therapy must be undertaken before attempting an intervention which poses a one way street and past the point of no return. Only a collaborative effort, as seen in the true heart team, will lead to broad clinical adoption by primary care physicians and drive referral. Obviously more clinical data are necessary to substantiate the personal opinion presented herein.


References

Price MJ et al. Circulation 2014;130:202‒212

Reddy VY et al. JAMA 2014 Nov 19;312(19):1988‒98.

Ailawadi G et al. The Journal of thoracic and cardiovascular surgery 2011;142:1002‒1009, 1009 e1001

Emmert MY et al. European Journal of Cardio-Thoracic Surgery  2014;45:126‒131

Ohtsuka T et al. JACC 2013;62:103‒107


Sacha Salzberg is a cardiovascular surgeon at Heart Clinic Hirslanden, Zurich, Switzerland. He receives grants and speak
ing fees from AtriCure

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