Left Atrial Posterior Wall Thrombus After Posterior Wall Ablation

Background: Posterior wall isolation for recurrent atrial arrhythmia is a commonly used technique to achieve long-term freedom from atrial fibrillation. Despite the widespread use of posterior wall isolation, its long-term effects on left atrial function are unknown. Specifically, the effect of isolated atrial walls on stasis and risk of thrombus has not been established. We present the case of a patient who developed a left atrial posterior wall thrombus after a posterior wall isolation attempt. Case Report: A 67-year-old female with a complex electrophysiologic history was found to have a left atrial posterior wall thrombus when she presented for a third ablation attempt for drug-refractory macroreentrant left atrial tachycardia 5 weeks after a posterior wall isolation attempt. The patient had a number of risk factors that could have been associated with the unusually located thrombus: hypertension, low ejection fraction, mitral valve disease, and recurrence and sustained duration of symptomatic atrial fibrillation. After the patient had 3 weeks of anticoagulation treatment, transesophageal echocardiography showed no left atrial thrombus, and she underwent successful reisolation of the posterior wall. The third ablation was successful, and the patient developed no complications of stroke, transient ischemic attack, or systemic embolization throughout her treatment course. Conclusion: To our knowledge, this case is the second report of a left atrial posterior wall thrombus in this setting. The patient's complex and specific set of risk factors likely led to this rare finding. Although left atrial posterior wall thrombus after ablation is rare, in patients with specific risks or a combination of factors that could lead to such a clot, visualizing the left atrium in these patients may be beneficial to minimize the risk of systemic embolization.