Weighing the risks and benefits of anticoagulation in atrial fibrillation: a case report of left atrial appendage absence in a patient referred for procedural occlusion.

Background: The absence of the left atrial appendage is an exceedingly rare structural variant that could have important implications for anticoagulation regimens in patients with atrial fibrillation. Case summary: We report the case of a 63-year-old Puerto Rican female with a history of hypertension, cerebral artery aneurysms, and type 2 diabetes mellitus who suffered multiple haemorrhagic strokes. The patient had never received anticoagulation therapy. During the indicated stroke work-up, the patient was found to have paroxysmal atrial fibrillation. Given the patients high risk for thromboembolism and contraindications to anticoagulation therapy, the patient was referred for left atrial appendage occlusion. Pre-procedural transoesophageal echocardiography failed to identify the left atrial appendage. Evaluation by way of cardiac computed tomography confirmed absence of the left atrial appendage. Left atrial appendage occlusion could not be carried out. The patient had been deemed being at high risk of bleeding, was not anticoagulated, and was instead closely followed. The patient has not had thrombo-embolic events nor has she experienced a haemorrhagic stroke recurrence at follow-up appointments. Discussion: To our knowledge, this is the first such case report that reports left atrial appendage absence in the setting of multiple haemorrhagic strokes. Given the rarity of the condition and lack of available guidelines, the most viable way to currently manage this patient population is on a case-to-case basis. However, we propose that absence of the left atrial appendage could confer a decreased risk of thrombo-embolic phenomena in patients with atrial fibrillation.