PATENT FORAMEN OVALE - ASSOCIATION BETWEEN THE DEGREE OF SHUNT BY CONTRAST TRANSESOPHAGEAL ECHOCARDIOGRAPHY AND THE RISK OF FUTURE ISCHEMICNEUROLOGIC EVENTS

This study investigated whether there is an association between the de gree of interatrial shunting across a patent foramen ovate, as determi ned by saline contrast transesophageal echocardiography, and the risk of subsequent systemic embolic events, including stroke. Thirty-four p atients found to have patent foramen ovate during transesophageal echo cardiography were divided into two groups on the basis of the maximum number of microbubbles in the left heart in any single frame after int ravenous saline contrast injection: group 1 (n=16) with a ''large'' de gree of shunt (greater than or equal to 20 microbubbles) and group 2 ( n=18) with a ''small'' degree of shunt (greater than or equal to 3 but <20 microbubbles). Patients were followed up over a mean period of 21 months for subsequent systemic embolic events, including transient is chemic attack and stroke. Five (31%) of the patients with large shunts had subsequent ischemic neurologic events, whereas none of the patien ts with small shunts had embolic events (p=0.03). These events occurre d in spite of antiplatelet or anticoagulant therapy. We conclude that patients with a large degree of shunt across a patent foramen ovale, a s determined by contrast transesophageal echocardiography, are at a si gnificantly higher risk for subsequent adverse neurologic events compa red with patients with a small degree of shunt.