Microembolic signals in patients undergoing coronary artery bypass grafting - Effect of aortic atherosclerosis

The aim of this prospective study was to determine whether aortic atheroscl erotic plaques are associated with increased frequency of microembolic sign als and stroke in patients who undergo coronary artery bypass grafting. A t otal of 69 such patients were monitored by transcranial Doppler ultrasonogr aphy for 30 minutes before and after surgery. To our knowledge, this study is the Ist in which in vivo pathologic analysis of aortic plaques was syste matically performed - and microembolic signals monitored - before and after open-heart surgery. Plaques were assessed by transesophageal echocardiogra phy and by biopsy of materials taken during surgery. The frequency of micro embolic signals was evaluated with regard to the occurrence of postoperativ e stroke. In the preoperative phase, only 10 of 48 patients with aortic pla ques had microembolic signals, and the mean count of microembolic signals w as 3.2 +/- 1.2 per hour At the conclusion of 24 postoperative hours, 29 pat ients (42%) displayed such signals (mean count 9.8 +/- 3.1/h). Seven of the 48 patients (15%) with aortic atherosclerosis had cerebral ischemic events , but none of those with normal aorta (21 patients) experienced stroke duri ng the postoperative phase. During postoperative monitoring, patients with stroke had higher microembolic-signal counts than did those with normal aor ta (17.4 +/- 3.3/h vs 5.9 +/- 3.1/h; P <0.05). Our findings suggest that mi croembolic signals can be a marker of severe aortic atherosclerosis and tha t monitoring these signals should enable the application of appropriate sur gical methods to coronary artery bypass patients who are at higher risk of stroke.