Congenital left atrial appendage aneurysm with unexpected course of left anterior descending coronary artery.

The left atrial appendage (LAA) aneurysm is a rare condition that can produce local compressive effects and complications including supraventricular tachyarrhythmias, thromboembolic events and myocardial ischaemia. We present a rare case of a neonate with a congenital LAA aneurysm which resulted in local compressive effects on the left ventricle, severe mitral regurgitation and malposition of the left anterior descending (LAD) coronary artery. Intraoperatively, the LAD was found to be within the aneurysmal wall exterior to the left ventricular epicardium and was inadvertently injured during LAA aneurysm resection. Retrospective review of the preoperative computed tomography and echocardiography scans demonstrated the LAD lying within the wall of the LAA aneurysm, although this had not been well appreciated at that time. This highlights the importance of thorough multimodal preoperative imaging and intraoperative assessment for recognition of this rare association between the LAA aneurysm and LAD malposition, and prevention of inadvertent LAD injury during aneurysm resection.