Spontaneous left atrial thrombus during patent foramen ovale closure.

A 52-year-old male smoker suffered a left-sided stroke. Bubble contrast echocardiography demonstrated an aneurysmal atrial septum and patent foramen ovale (PFO). The patient was referred for percutaneous closure of his PFO to reduce his risk of further stroke. Despite dual antiplatelet therapy and pre-procedural heparin, he developed a spontaneous thrombus during balloon sizing of the defect identified by transoesophageal echocardiography. The balloon was immediately withdrawn to the right side and removed. Periprocedural echocardiography using either transoesophageal or intracardiac echo is essential to monitor for this potential procedural complication of percutaneous PFO closure.