Natural history of descending thoracic and thoracoabdominal aneurysms

Background. A review of 165 patients with chronic dissecting and degenerative aneurysms of the descending thoracic and thoracoabdominal aorta initially managed nonoperatively was carried out to ascertain factors associated with a high risk of rupture. Methods. Changes in the aneurysms were followed with three-dimensional reconstructions of computed tomograph scans. Risk factors were compared in patients with dissecting and nondissecting aneurysms who experienced rupture, in whom operation was recommended during the course of follow-up, and in those without rupture or operation. Results. Nondimensional variables associated with an enhanced risk of rupture include age, the presence of chronic obstructive pulmonary disease, and even uncharacteristic continued pain. Patients with rupture of dissections had significantly higher blood pressures than survivors, and significantly smaller maximal descending thoracic aortic diameters (median 5.4 cm) than patients with rupture of degenerative aneurysms (median 5.8 cm). The extent of the aneurysm, as reflected by the maximal abdominal aortic diameter, was a significant risk factor for rupture only in nondissecting aneurysms. Mortality from rupture was significantly higher in patients with chronic dissections than in patients with nondissecting aneurysms: 9/10 vs 26/34 (p = 0.004). Conclusions. Almost 20% of patients followed nonoperatively succumbed to rupture, suggesting that a more aggressive surgical approach toward patients with chronic aneurysms of the descending thoracic and thoracoabdominal aorta is warranted. An individualized risk of rupture within 1 year can now be calculated, and patients whose operative risk is lower than their calculated risk should be offered elective surgery. (C) 1999 by The Society of Thoracic Surgeons.