[Acute type B aortic dissection: prognosis after initial conservative treatment and predictive factors for a complicated course].

OBJECTIVE: Today there is still debate concerning the optimal mode of treatment for type B dissection of the aorta. Controversies are mainly due to discordant results regarding survival following medical or surgical treatment. We assessed the early and long-term outcome of acute dissection of the descending aorta after initial conservative treatment.

METHODS: Between 1980 and 1995, 225 patients were hospitalized in the medical or surgical department of our institution with the diagnosis of acute type B aortic dissection. 38 patients (16.8%) underwent replacement of the descending aorta within the first week after hospital admission. Primary indications for immediate surgery were rupturing aneurysm in 15 patients, extensive dilatation of the descending aorta in 13, distal malperfusion in 8, and pseudocoarctation syndrome with uncontrollable hypertension in 2. All other patients (n = 187) underwent primary conservative treatment in the intensive care unit, which included appropriate antihypertensive medication.

RESULTS: Hospital mortality during and after initial conservative treatment was 17.6% (33/187 patients). Main causes of death were rupture in 14 patients, intestinal malperfusion in 13 and cardiac failure in 3, whereas in 3 patients the cause of death could not be determined. Nine additional patients had to be referred for early surgery during the initial hospitalization because of contained rupture (n = 4), rapidly increasing size of the aorta (n = 2) and suspected intestinal ischemia (n = 3). Hospital mortality after early surgery was 21% (8/38 patients) for the overall time period. After hospital discharge from the initial acute dissection, surgery for chronic dissection was performed in 47 patients, mainly because of expanding descending aortic aneurysm. Hospital mortality was 8% in these patients (4/47). Actuarial survival rates after primary conservative therapy were 76 +/- 5% and 50 +/- 7% after 5 and 8 years respectively.

CONCLUSION: Currently, surgery for acute type B dissection is limited to patients with rupturing disease, distal malperfusion or uncontrollable hypertension and pains. Despite aggressive antihypertensive treatment, hospital mortality after primary conservative treatment is still high and a substantial proportion of patients requires surgery during initial hospitalization. Although conservative treatment is recommended in most uncomplicated type B aortic dissections, early surgery should be considered in the following situations: younger patients with 5 cm diameter of the aorta at initial evaluation, as well as those with Marfan syndrome, patients with limited false aneurysm or retrograde dissection into the aortic arch, and those with poor medical compliance or uncontrollable proximal hypertension. Radiographic follow-up for an indefinite period may allow detection of potential late complications and proper planning of elective operations when indicated.