Objective:

To present an extremely rare case of unroofed coronary sinus (UCS) in an adult with prior cryptogenic strokes now presenting with acute large vessel occlusion.

Background:

Unroofed coronary sinus represents the rarest subtype of atrial septal defect (ASD), with an estimated prevalence below 1%. UCS arises from a congenital deficiency of the coronary sinus roof, creating an abnormal communication between the right atrium and the left atrium. Adult diagnosis is exceptionally rare, particularly in patients presenting with acute embolic large vessel occlusion leading to stroke. 

Design/Methods:

Case report.

Results:

A 62-year-old man with a remote history of right middle cerebral artery (MCA) infarction 17 years prior—presumed secondary to paradoxical embolism via a patent foramen ovale (PFO) and treated with PFO closure—presented with right-sided weakness, facial droop, and aphasia. Imaging confirmed left MCA M1 segment occlusion, and he underwent successful mechanical thrombectomy. Due to recurrent stroke, a comprehensive evaluation—including hypercoagulable studies—was performed and proved negative. Transthoracic echocardiography revealed early appearance of bubbles in the left ventricle within four cardiac cycles, suggestive of intracardiac shunting. Transesophageal echocardiography demonstrated right-to-left flow across an unroofed coronary sinus; notably, there was no residual shunt across the prior PFO/ASD closure device. Cardiac CT further characterized a markedly dilated coronary sinus (maximum 18 mm) with an 8 mm communication to the left atrium. After exclusion of alternative stroke etiologies, paradoxical embolism through the unroofed coronary sinus was determined to be the underlying cause. The defect was surgically closed for secondary prevention, and the patient was discharged on antiplatelet therapy and high-dose statin, with anticoagulation deemed unnecessary post-closure. 

Conclusions: