AORTIC DISSECTION TYPE-A VERSUS TYPE-B - A DIFFERENT POSTSURGICAL DEATH HAZARD

Objective: Patients with type B aortic dissection differ from patients with type A dissection in age, hypertension prevalence, indications a nd timing of surgical treatment, yet reported long-term results have b een rather similar (see Doroghazi et al. J Am Coll Cardiol 1984;3:1026 -1034). Methods: With the aim of comparing the post-surgical history, we have reviewed our results in 288 dissections, 213 type A and 75 typ e B, operated consecutively between 1 January 1970 and 31 November 199 4. Follow-up was 100% complete. Empirical survival of both groups was interpolated with a fully parametric method anti the shape and scale o f the hazard function was investigated. Results: Survival was not sign ificantly different between type A and type B. Parametric survival was , respectively, 0.52% (70% C.L.: 0.48-0.55) vs. 0.56% (0.51-0.62) at 5 years. 0.44% (0.40-0.47) vs. 0.28% (0.23-0.25) at 10 years. 0.37% (0. 33-0.41) vs. 0.25% (0.19-0.32) at 15 years, and 0.31% (0.26-0.35) vs. 0.24% (0.18-0.31) at 20 years. Following the high perioperative risk p hase in type A dissection, the intermediate and late risk remains cons tant at a rate of 0.0033 events/month (3.9% patient-years (pt.-years)) . By contrast, the postoperative course of type B dissection shows an intermediate risk phase between 4 and 10 years with an average lineari zed risk of 9.3% pt.-years and a peak of 20%. This determined lower su rvival rates (24 vs. 31% at 20 years, P = NS). Conclusions: We conclud e that patients with type B dissection have a steeper postoperative de ath hazard as compared to type A dissection patients. Age confounding or late entry do not explain the difference. This could be possibly re lated to a greater propensity for expansion. higher risk of malperfusi on complications or to limitations of our current surgical treatment. (C) 1997 Elsevier Science B.V.