Discussion
LAA aneurysm is an extremely rare entity. It has slight female preponderance and is usually diagnosed in the third decade of life.1 It is often discovered incidentally on imaging studies in the absence of symptoms.2 LAAA is classified as congenital or acquired with >90% of the cases being congenital thought to arise from congenital dysplasia of the pectinate muscles.2 It is rarely associated with other cardiac anomalies such as atrial or ventricular septal defect.1,2 Acquired causes of LAAA include mitral valve disease or elevated left atrial pressure.2
Most common symptoms associated with LAAA include palpitations and dyspnea.1 Other symptoms include chest pain and systemic thromboembolism. Significantly enlarged LAA provides a substrate for atrial or supraventricular tachyarrhythmias such as SVT, atrial tachycardia, fibrillation or flutter, which manifest as palpitations. Aneurysmal dilatation of the LAA results in stasis of blood and predisposes to thrombus formation. Additionally, these patients are at high risk of developing atrial fibrillation or flutter which further increases thromboembolic risk.1 The incidence of stroke or systemic thromboembolism in LAAA ranges from 6-16%.1,2 Rarely, a large LAAA compresses the coronary arteries resulting in myocardial ischemia presenting as angina.3
LAAA is usually diagnosed with multimodality imaging including echocardiography, CT and MRI. Notably, in large LAA aneurysms, chest X-ray is abnormal with cardiomegaly and enlarged left heart border [Figure 2].1 TTE is useful as an initial tool for evaluation of LAAA.4 Transesophageal echocardiography is valuable for thrombus detection.5 Contrast echocardiography aids in confirming the diagnosis as well as ruling out thrombus formation.4 CT diagnoses LAAA with a high degree of accuracy and offers additional advantage of assessing coronary anatomy.2
Surgical resection remains the cornerstone of therapy for LAAA. Early surgical intervention is recommended given the risk of thromboembolic complications.6 Median sternotomy is the preferred surgical approach in majority (85%) of the cases.2Other less invasive approaches such as left lateral thoracotomy, mini-thoracotomy and endoscopic resection have been described7-9, however, these approaches are more suited for smaller aneurysms without intra-aneurysmal thrombi. Additionally, there is risk of incomplete closure with minimally invasive approach.9 Therefore, for large LAAA (such as in our case) median sternotomy with CPB is recommended to minimize the risk of thromboembolic complications resulting from dislodgement of small thrombi during surgical manipulation1 and to provide a clear field to accurately and completely resect the aneurysm and avoid coronary artery injury [e.g. left circumflex artery located at the base of LAA].6 After successful surgical treatment, the prognosis is excellent with freedom from recurrent symptoms, arrhythmia and thromboembolic events reported in long term follow-up.1,2