Discussion

Aneurysm of the left atrial appendage is a rare anomaly; with about 50 published case reports.Reference Lekkerkerker, Jaarsma and Cramer ³ Some authors describe it as a “dangerous fifth chamber”.Reference Tigen, Dogan, Guler, Hatipoglu, Yanartas and Kirma ⁴ The majority of these cases are congenital, although there are also reports of aneurysms acquired because of an elevation of the left atrial pressure.Reference Foale, Gibson, Guyer, Gillam, King and Weyman ⁵ It generally presents as an isolated cardiac malformation and is related to dysplasia of the pectinate muscles in the left atrial appendage and of the bands of atrial muscle from which they arise.Reference Victor and Nayak ⁶ They are rarely diagnosed during childhood and generally become manifest during the second or third decades of life.Reference Pome, Pelenghi, Grassi, Vignati and Pellegrini ⁷ Our patient presented with intermittent episodes of fever, chills, and headaches followed, after the diagnosis of the left atrial appendage aneurysm, by the development of a femoral artery embolism, despite the absence of an atrial arrhythmia such as atrial fibrillation. Although most patients with this cardiac malformation are reported to be asymptomatic, some can present with palpitations related to atrial arrhythmias, dyspnea, angina related to compression of the left coronary artery, and cerebrovascular incidents due to systemic embolisation. Atrial thrombi occur, especially in patients with atrial arrhythmias, and also in the absence of arrhythmias. Thrombosis with subsequent systemic embolisation has been reported, similar to our case. Stasis of blood within the aneurysm may be the predisposing factor for thrombus formation.Reference Krueger, Ferlic and Mooring ⁸ Radiographically, a left atrial appendage aneurysm must be differentiated from other pathologies such as a mediastinal mass, pericardial cyst, cardiac tumour, and a pericardial or extracardiac fluid collection. They are not linked to any other pathologies and should be distinguished from other diagnoses such as congenital deficit of the pericardium with atrial herniation, mitral valve pathology causing atrial dilation, or juxtaposition of the atrial appendages. Suggested criteria for the diagnosis of a congenital left atrial appendage aneurysm include (1) the absence of any concomitant cardiac pathology that could cause atrial dilation, (2) the presence of a left atrium and appendage of normal morphological characteristics, (3) a direct continuity of blood flow between the left atrium and the appendage, and (4) the absence of pericardial defects.Reference Gold, Afifi, Ko, Horner and Hahn ⁹ The diagnosis is usually made by transthoracic and/or transoesophageal echocardiography. Cardiac magnetic resonance imaging can also play an important role in diagnosis. Once the diagnosis has been established, aneurysms of the left atrial appendage must be treated because of their potential morbidity and mortality. The recommended treatment is resection, generally using cardiopulmonary bypass. However, good surgical results have also been reported through a left thoracotomy incision without cardiopulmonary bypass.Reference Pome, Pelenghi, Grassi, Vignati and Pellegrini ⁷ Surgery has been proven to be effective both in the prevention of new atrial arrhythmias and of systemic emboli. There are case reports in the literature of patients who are free of atrial arrhythmias 8 years after aneurysmectomy.Reference Mathur, Zehr, Sinak and Rea ^{10 ,} Reference Victor and Nayak ⁶ Although resection alone is usually adequate, it is sometimes combined with the Cox-Maze procedure for ablation of the atrial fibrillation pathways, especially if there is clinically important dilation of the left atrium or if a previous electrophysiological study has shown induction of atrial fibrillation by atrial foci.Reference Mathur, Zehr, Sinak and Rea ¹⁰ As demonstrated by our case, it seems judicious to offer elective aneurysmectomy to an asymptomatic patient with a congenital aneurysm of the left atrial appendage as a prophylactic measure to minimise the chances of the future development of systemic embolisation or atrial arrhythmias.