Natural history of descending thoracic and thoracoabdominal aneurysms

Background. A review of 165 patients with chronic dissecting and degenerati ve aneurysms of the descending thoracic and thoracoabdominal aorta initiall y managed nonoperatively was carried out to ascertain factors associated wi th a high risk of rupture. Methods. Changes in the aneurysms were followed with three-dimensional reco nstructions of computed tomograph scans. Risk factors were compared in pati ents with dissecting and nondissecting aneurysms who experienced rupture, i n whom operation was recommended during the course of follow-up, and in tho se without rupture or operation. Results. Nondimensional variables associated with an enhanced risk of ruptu re 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 p atients 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. Mor tality from rupture was significantly higher in patients with chronic disse ctions than in patients with nondissecting aneurysms: 9/10 vs 26/34 (p = 0. 004). Conclusions. Almost 20% of patients followed nonoperatively succumbed to ru pture, suggesting that a more aggressive surgical approach toward patients with chronic aneurysms of the descending thoracic and thoracoabdominal aort a is warranted. An individualized risk of rupture within 1 year can now be calculated, and patients whose operative risk is lower than their calculate d risk should be offered elective surgery. (C) 1999 by The Society of Thora cic Surgeons.