Cardiac surgery
Left atrial appendage stapling during totally thoracoscopic ablation of long-standing lone persistent atrial fibrillation – lessons learnt

Introduction

Atrial fibrillation (AFib) is the most prevalent cardiac arrhythmia and its occurrence increases with aging of the general population [1, 2]. Morbidity and economic costs make AFib one of the most important challenges in recent medicine. As pharmacological treatment has poor results, different ablation techniques are developed. In many publications surgical ablation was proved to have superior results in sinus rhythm restoration compared to catheter ablation [2-4]. According to the global trend in minimizing surgical access recently many minimally invasive surgical techniques have been under evaluation [4-6]. Along with the disabling symptoms of AFib, the risk of thromboembolic events dramatically rises. According to the literature in over 90% the source of embolic material in non-valvular atrial fibrillation is the left atrial appendage (LAA) [2, 7, 8]. This makes LAA exclusion one of the main goals in the treatment of patients with non-valvular AFib.

Aim of the study

Here we describe the totally thoracoscopic technique of LAA exclusion during bilateral ablation for lone persistent and long-standing persistent AFib.

Material and methods

Nineteen patients (12 men, 7 women) admitted to our department between November 2011 and February 2013 with persistent and long-standing persistent atrial fibrillation underwent totally thoracoscopic ablation of arrhythmia with left atrial appendage stapling. Mean age, AFib duration, EuroSCORE II, CHA2DS2-VASc score, left atrial dimension and LVEF were 57.8 ±11 years, 52.6 ±50 months, 0.67 ±0.2%, 1.5 ±1.3, 41 ±63 mm and 63.7 ±6.5%, respectively. One patient (5.8%) experienced prior stroke. All patients underwent transesophageal echocardiography before the operation to rule out thrombus or blood sludge in LAA. Ablation was performed with the ORLab system (AtriCure, Ohio, USA). LAA exclusion was performed as the last step of the procedure using the new Tri-Staple stapler (Covidien, Mansfield, USA).

Results

No mortality was observed. All but one patient (95%) were eligible for LAA stapling. The stapler placement and LAA separation take a few minutes. We did not observe early (intraoperative) or late bleeding from the stapler line. There was one case of bleeding from the left atrial wall connected with a tear during LAA stapling successfully treated surgically. In transthoracic echocardiography we obtained confirmation of complete LAA exclusion with smooth endocardium. No incidence of stroke or TIA in follow-up was noted. Good atrial transport function and anatomical results of LAA exclusion in echocardiography were observed in all patients.

Discussion

Stroke and transient ischemic attack (TIA) are the most devastating complications in patients with atrial fibrillation. Stroke risk rises 5-fold in presence of AFib and one in five strokes is attributed to this arrhythmia [1, 7, 8]. Strokes associated with AFib are more often fatal (risk of death is doubled), and more devastating in symptoms [1]. Moreover, undiagnosed so-called “silent AFib” can cause cryptogenic strokes [1]. This makes prevention of stroke/TIA one of the most important goals in AFib treatment. Anticoagulation therapy significantly reduces absolute annual risk in all strokes by 2.7% [9]. However, its introduction is based on presence of risk factors assessed by risk scales such as CHADS2 and CHA2DS2-VASc scores, requires regular blood tests and precise adjustment of dosage, and increases the risk of bleeding [1, 9]. As stand-alone AFib also occurs in younger, working patients with no additional risk factors, the problem of AFib-related strokes is even more important. Some authors have reported that over 90% of thromboembolic material has its origin in the left atrial appendage (LAA) [7]. Moreover, in a recently published study the authors correlated left atrial appendage morphology assessed in magnetic resonance and computed tomography with risk of stroke in patients with AFib [8]. They divided LAA into four types – Chicken Wing, Windsock, Cauliflower and Cactus. According to their results, Chicken Wing LAA morphology is the most prevalent (48% of their population) and with the least risk of stroke/TIA, but all patients with non-Chicken Wing morphology had strikingly increased risk of thromboembolic events up to 4.6% (10-fold) [8]. What is even more important, this increased risk was independent from low risk assessed on the above-mentioned scales [8]. Recently there is much interest in LAA occlusion (LAAO) techniques with percutaneous devices such as WATCHMAN, LARIAT, Amplatzer or cardiac plug [10-15]. However, there are concerns about safety and efficacy of LAAO devices mainly connected with dislodgement of the device and complications related to low operator experience [12].

In our department we started a minimally invasive approach in surgical treatment of patients with lone persistent and long-standing persistent atrial fibrillation with totally thoracoscopic access (Fig. 1). In the last stage as prevention of stroke/TIA we perform excision of the left atrial appendage. Therefore we use an endoscopic Endo-GIA stapler with the novel Tri-Staple reloads (Covidien, Mansfield, USA). Tri-Staple has very good properties in hermetic tissue squeezing with a sealed stapling line. We introduce the stapler through the 6th or 7th intercostal space above the diaphragm. The reload has two arms – the one with staples is longer, massive and movable, while the second is shorter, flat and still. According to our experience the proper stapler placement with still arm beneath and movable arm above the LAA is crucial (Fig. 2). In such a position the base of the LAA is tightened to the firm flat surface of the still arm under continuous visual control of squeezed tissues (Fig. 3). This procedure takes only a few minutes, and thus does not prolong the operation. In case of incomplete separation of the distal end of the LAA it is feasible to apply a green reload (Fig. 4). However, in such a situation during our procedures the remaining tissue was not the true left atrial wall but just connective and fatty tissue. It is sufficient to use a vascular clip to safely separate the LAA (Fig. 5). In one patient as a result of stapling we observed a massive tear of the left atrial wall just beneath the appendage base which required sewing via sternotomy. After stopping the bleeding we observed a complete, sealed stapler line. In our opinion the injury was caused by rotation of the reload so that the movable, longer arm was downward and while closing the device we pulled up the left atrial wall with the tip of the longer arm, leading to its tension and tear. After this case we did not reverse the reload, and such a situation has not been repeated. Only one in 19 patients had such a small, flat left atrium that we were not able to grasp it with the stapler arms. Other LA appendages, even small ones but with a defined base, were eligible for safe excision.

Conclusions

Primary and secondary stroke prevention is crucial in the treatment of patients with all types of atrial fibrillation. As the left atrial appendage is the main site of thrombus formation in this population, we should search for effective and safe methods of its exclusion. In our experience totally thoracoscopic LAA stapling is feasible and safe when done with caution and proper use of the stapler. Further studies including prospective randomized trials in this group of patients are needed

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