Natural history of severe atheromatous disease of the thoracic aorta: transesophageal echocardiographic study

Objectives. This study sought to prospectively observe the morphologic and clinical natural history of severe atherosclerotic disease of the thoracic aort as defined by transesophageal echocardiography. Background. Atherosclerosis of the thoracic aort has been shown to be highly associated with risk for embolic events in transesophageal studies, but the natural history of the disease under clinical conditions has not been reported. Methods. During 20-month period, 191 of 264 patients undergoing transesophageal echocardiography had adequate visualization of the aort to allow atherosclerotic severity to be graded as follows: grade I = normal (44 patients); grade II = intimal thickening (52 patients); grade III = atherom <5 mm (62 patients); grade IV = atherom ≥5 mm (19 patients); grade V = mobile lesion (14 patients). All available patients with grades IV (8 patients) and V (10 patients) disease as well as subgroup of 12 patients with grade III disease had follow-up transesophageal echocardiographic studies (mean [±SD] 11.7 ± 0.9 months, range 6 to 22). Results. Of 30 patients undergoing follow-up transesophageal echocardiographic studies, 20 (66%) had no change in atherosclerotic severity grade. Of the remaining 10 patients, atherosclerotic severity progressed one grade in 7 and decreased in 3 with resolved mobile lesions. Of 18 patients with grade IV or V disease of the aort who underwent follow-up study, 11 (61%) demonstrated formation of new mobile lesions. Of 10 patients with grade V disease on initial study who underwent follow-up study, 7 (70%) demonstrated resolution of specific previously documented mobile lesion. However, seven patients (70%) with grade V disease also demonstrated development of new mobile lesion. Of 33 patients with grade IV or V disease, 8 (24%) died during the study period, and 1 (3%) had clinical embolic event. Conclusions. The presence of severe atherosclerotic disease of the thoracic aort as defined by transesophageal echocardiography is associated with high mortality rate. Although the morphologic natural history of the disease process itself is marked by stability over 1-year period, individual lesion morphology is dynamic, with formation and resolution of mobile components occurring frequently over the same period. The dynamic nature of individual lesion morphology potentially enhances the possibility of developing successful therapeutic strategy.