Ectopic Focus in an Accessory Left Atrial Appendage

Abstract

A 65-year-old man with symptomatic atrial fibrillation refractory to medical therapy was referred for repeat pulmonary vein (PV) isolation. Clinical symptoms included paroxysmal palpitations once to twice per week with associated light-headedness and chest pain. Initial PV isolation had been performed 6 months earlier without cessation of atrial fibrillation despite combined medical therapy with oral flecainide and bisoprolol. His past medical history was significant for hypertension, and in his family history, 1 brother had experienced a stroke at the age of 57 years. Physical examination, ECG, chest radiography, and coronary angiography were normal. Holter 24-hour ECG recordings revealed occasional atrial premature beats and paroxysmal atrial tachycardia.A magnetic resonance imaging study of the patient's PVs and left atrium (LA) was performed before the repeat radiofrequency ablation. Images were acquired with a 1.5-T whole-body magnetic resonance system (Siemens Avanti, Siemens Medical Solutions, Forcheim, Germany) with an 8-element cardiac synergy coil for radiofrequency signal reception. First-pass breath-hold 3-dimensional contrastenhanced magnetic resonance angiography of the PV was obtained after pump injection (3 mL/s) of 15 mmol of gadobutrol (Gadovist, Bayer Schering Pharma, Berlin, Germany), followed immediately by a 15-mL saline flush (data acquisition began after a delay determined by a small timing bolus given before the 3-dimensional acquisition). Breath holding was performed at end-inspiration. A spoiled 3-dimensional gradient-echo sequence with the following parameters was used: Repetition time 3.19 ms, echo time 1.03 ms, flip angle 25°, 120 slices, slice thickness 1.6 mm, field of view 470 mm, matrix 227ϫ384. Multiplanar reformations demonstrated a normal configuration of the PVs with no evidence of PV stenosis. An accessory LA appendage was identified on the anterior LA wall, 9 mm medial to the ostium of the right superior PV (Figure 1). The orifice of the accessory appendage measured 2 cm in maximal diameter and 1.5 cm in depth.Electrophysiological mapping was performed via right femoral access. A duodecapolar catheter (Staplemapr, Medtronic, Minneapolis, Minn) was placed within the coronary sinus to record LA electrical activity and for pacing. Figure 1. A, Axial-oblique magnetic resonance image of the LA showed an accessory appendage (straight arrow) arising from the anterior wall. The appendage was clearly separated from the LA appendage (curved arrow). B, Sagittaloblique magnetic resonance image confirmed that the accessory appendage arose from the superior portion of the anterior LA wall, and extended into the transverse pericardial recess. AO indicates aorta; PA, pulmonary artery. From the Departments of Radiology

Clinical Significance of Left Atrial Anatomic Abnormalities Identified by Cardiac Computed Tomography

“…The prevalence of accessory appendages in our investigation (28%) is in congruence with preceding studies which have shown prevalence between 10% -28% [6] [7] [9] [12] [21]. Moreover, accessory left atrial appendages have been implicated as the source of ectopy in patients with symptomatic atrial fibrillation refractory to medical treatment [16] [17]. Although some have contended the clinical significance of accessory appendages, describing these structures as anatomic variants as opposed to pathologic findings, the current analysis attempts to elucidate this question [6].…”

“…Atrial fibrillation originating from the left atrium has been implicated in cerebrovascular accidents (CVA) and transient ischemic attacks (TIA) [14] [15]. Recently, ectopic fibrillatory activity and thrombus has been described in patients with accessory appendages and diverticula [10] [13] [16] [17]. Septal pouches, given their blind end morphology, have been implicated in case reports of thromboembolic disease as well as arrhythmia [5] [18]- [20].…”

Lack of Association between Stroke and Left Atrial Out-Pouching Structures: Results of a Case-Control Study

“…Second, we could not reveal how the size of LA out-pouching structures affected the patients because most of the LA out-pouching structures detected in our study population were very small (less than 1cm) and the largest one measured just 1.2cm in diameter. In previous reports, the thrombogenic or arrhythmogenic potential of LA out-pouching structures were initially suggested in patient cases with large accessory LA appendages or diverticula [10,19,21]. Therefore, the effect of LA out-pouching structure size should be further investigated.…”

Is there an association between left atrial outpouching structures and recurrence of atrial fibrillation after catheter ablation?

“…There are a few case reports describing that LADs and other accessory appendages are a potential source of thromboembolism and a potential cause of perforation risk during ablation [ 19 , 20 , 32 ]. Interestingly, histopathological analyses could demonstrate that LADs contain trabeculated myocardium which raises the hypothesis that LAD may be contractile and a source of ectopic activity, which was reported in a documented case report by Kileen et al [ 24 ]. However, the role of LADs in the pathomechanism of AF remains unclear.…”

“…They are reported to serve as an extra cardiac pacemaker focus, and comprise a risk factor for intracavitary thrombosis and cardiac perforation during ablation [ 19 – 23 ]. According to histopathological analyses, LADs contain trabeculated myocardium with the same wall structure as the surrounding myocardium and were firstly reported to show ectopic activity in a documented case report in 2009 [ 24 , 25 ]. Left sided septal pouches (LSSP) are considered structures that occur when the patent foramen ovale (PFO) is absent but the septum primum and septum secundum are not completely fused [ 26 ].…”