Original Article
Left Atrial Appendage Exclusion Using the AtriClip Device: A Case Series

https://doi.org/10.1016/j.hlc.2017.12.006Get rights and content

Background

Atrial fibrillation (AF) affects 1.5–2% of the population and is associated with a five-fold increased lifetime risk of stroke [1]. The left atrial appendage (LAA) is the source of embolic strokes in up to 90% of patients with non-valvular AF with clots in the left atrium [2].

Methods

We reviewed the clinical notes and echocardiographic findings of 20 patients who underwent open cardiac surgery in which concurrent AtriClip (Atricure Inc, Westchester, OH, USA) device insertion was attempted at our institution from July 2013 to February 2015. This was to examine the safety and efficacy of LAA exclusion with clip devices during open cardiac surgery. Indications for LAA exclusion included a history or suspicion of atrial arrhythmia, left ventricular dilatation, or a history of transient ischaemic attacks.

Results

All 20 of the 20 participants had successful placement of the clip device (100% success rate). There were no adverse events related to the device and no perioperative mortality. There were three late deaths due to chronic obstructive pulmonary disease (COPD), leukaemia, and refractory congestive cardiac failure. No late device related complications were found on follow-up imaging in the remaining patients.

Conclusions

The results of our study demonstrate the LAA exclusion during open cardiac surgery with the AtriClip device is safe, has a 100% success rate, and appears to be stable over time.

Introduction

Atrial fibrillation is the most common persistent cardiac arrhythmia, affecting 1.5–2% of the population [2], [3]. The prevalence increases with age, reaching up to 15% in octogenarians [4]. Patients with non-valvular AF have a five-fold increased lifetime risk of stroke, and 17-fold risk with valvular AF, which are often fatal or lead to significant disability [3], [4], [5], [6].

The left atrial appendage (LAA) is a remnant of the embryonic left atrium [4], [5]. It is a 2–4 cm tubular structure with a thin, fragile wall, and separated from the left atrium by an oval shaped orifice, that is on average 1.1 cm in diameter. The LAA is the source of embolic strokes in up to 90% of patients with non-valvular AF who have clots in the left atrium [2], [7], [8], [9], [10], [11]. Studies have also implicated the LAA in the initiation and maintenance of AF [2], [12]. It can be the site of triggers that induce paroxysmal AF and of re-entrant drivers in persistent AF. Furthermore, the LAA can be the source of embolic material in the absence of AF in patients with significant left ventricular dysfunction [11]. Atrial thrombi, the majority located in the LAA, have been identified in approximately 15% of patients with severely dilated cardiomyopathy in sinus rhythm.

Recent guidelines recommend the CHA2DS-VASc2 stratification scheme to assess stroke risk in patients with non-valvular AF [13]. One point is awarded for each risk factor, including congestive cardiac failure, hypertension, age >75 (doubled), age 65 to 74 years, diabetes mellitus, stroke/transischaemic attack (TIA)/thromboemolism (doubled), vascular disease (myocardial infarction, complex aortic plaque, peripheral arterial disease), sex category (female). A patient with a score of 2 has an adjusted stroke rate of 2.2% per year, and this increases with increasing score. Oral anticoagulant with vitamin K antagonists (VKA) or novel oral anticoagulants (NOAC) for stroke prevention is recommended for patients with a score of 2 or more.

Warfarin, the most commonly used VKA, is associated with a 67% ischaemic stroke risk reduction [4]. However, its use is limited by the narrow therapeutic index, its need for frequent monitoring and dose adjustments, interaction with foods and other medications, and bleeding risk [5], [6], [10]. Up to 40% of patients have a relative or absolute contraindication to chronic warfarin therapy and of eligible patients nearly 50% will cease warfarin [5], [6].

Novel oral anticoagulants developed, including dabigatran, rivaroxaban, and apixaban, are also associated with bleeding risk and lack of widely available reversal agents [1], [3], [10]. They are cleared by the kidneys and so raise concerns for use in patients with renal impairment. Poor compliance is also an issue as they have short half-lives, with some requiring twice daily dosing, and the cost can be burdensome.

The 2017 guidelines for the management of AF provided a Class IIA recommendation that surgical management of the LAA may be considered in patients with AF undergoing cardiac surgery with level C evidence [14].

The LAA can be excised by amputating stapling devices or scissors [8], [10], [15]. It can also be excluded by suturing, with a running suture, purse string suture or external ligation, or by stapling. However, surgical ligation of the LAA is frequently incomplete with persistent flow demonstrated on transoesophageal echocardiography or remaining LAA stumps greater than 1 cm in maximum length after closure [2], [6], [8]. A study comparing methods of LAA closure found surgical closure of the LAA was incomplete in nearly 60% of cases [8]. Surgical excision of the LAA had the greatest success rate (73%) over suture exclusion (23%), and stapler exclusion (0%). In partially closed LAAs with persistent flow identified, the prevalence of LAA thrombus was as high as 67% in stapler exclusion and 46% in suture exclusion [6], [8]. Concerns remain regarding the risk of atrial tears and increased postoperative bleeding in surgical LAA occlusion, and the functional impact on haemodynamics [10], [11]. The LAA contributes around 30% of total atrial natriuretic peptide and a reduction in this may contribute to heart failure and fluid retention.

A number of devices for percutaneous closure of the LAA have been designed, including the Percutaneous Left Atrial Appendage Transcatheter Occlusion (PLAATOO), WATCHMAN, and Amplatzer devices [6]. However, the percutaneous approach is associated with high procedure failure rates and serious procedure and device related adverse events including air embolism, postoperative bleeding, cardiac perforation, pericardial effusion, device migration and sepsis [3], [6], [9], [10], [15].

Occlusion of the LAA during open cardiac surgery with external clips placed near the base of the LAA may be a safe and effective method to reduce the risk of embolic strokes in at risk patients.

Section snippets

Methods

This study reviewed the first 20 patients that underwent cardiac surgery via median sternotomy at our institution in which concurrent LAA closure with the AtriClip device was attempted. Ethics approval and informed consent from participants or their next of kin was obtained. Indications for LAA exclusion included a history or suspicion of atrial arrhythmia, left ventricular dilatation, or a history of transient ischaemic attacks. The clips were inserted at any point after sternotomy. The

Results

The mean age of the participants was 72.4 years, ranging from 52 to 83, and 75% were male [Table 2]. Eleven patients had a history or suspicion of an atrial arrhythmia; nine of which had AF, one had atrial flutter, and one a suspicion of an atrial arrhythmia. Of these 11 participants, all had a CHA2DS2-VASc score greater than two. Of the nine patients in sinus rhythm, eight had left ventricular dilatation, and one had a history of likely TIA. Nine participants were greater than 75 years of age,

Discussion

The safety and efficacy of LAA closure by surgical and percutaneous techniques for longitudinal thromboembolic morbidity prevention is a topic of much interest.

Salzberg et al. (2008) monitored seven adult baboons that underwent off-pump AtriClip device insertion, and at 130 days from insertion, direct inspection demonstrated stable device location, persistent LAA exclusion, and complete LAA fibrosis [17].

We reviewed the first 20 patients at our institution to have LAA occlusion with the AtriClip

Conclusion

Our case series suggests that LAA exclusion during open cardiac surgery with the AtriClip device may be a safe and effective procedure. All participants who met the inclusion criteria had the AtriClip device deployed successfully, without significant procedure or device related adverse events. At the time of data collection, none of the participants had clinical evidence of stroke following device insertion.

Disclaimer

Mr Yii is a consultant for AtriCure Inc.

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Oral presentation on the 13th November 2015 at the ATCSA Annual Scientific Meeting, Cebu, Philippines.

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