Warfarin anticoagulation in acute type A aortic dissection survivors (WATAS)

Background: Early survivors of acute type A aortic dissection (AAAD) remain at risk for late death and late aortic events. However, the frequency and long-term effects of warfarin anticoagulation on long-term outcome in post-surgical AAAD survivors have not been elucidated.

Methods: Two tertiary care centers performed a retrospective observational cohort study of warfarin anticoagulation in AAAD in 243 persons with early survival of surgical repair (WATAS). Serial postoperative tomographic imaging was available in 106 persons.

Results: A total of 88 postoperative AAAD survivors (36%) were on long-term warfarin anticoagulation. The indication for anticoagulation was a mechanical aortic prosthesis in 46 (52%), atrial fibrillation in 33 (38%), stroke in 7 (8%), and pulmonary embolism in 1 (1%). The indication for anticoagulation remained unclear in 1 person (1%). Survival and aortic event free survival were 98.3±0.01 and 98.7±0.01 at 1 year, and 76.4±0.03 and 91.8±0.02 at 5 years, respectively, with no differences irrespective of warfarin anticoagulation. Multivariate Cox regression analysis established higher age (P<0.001), and operation extending into the descending aorta (P=0.030) as independent predictors of late death. Follow-up without tomographic imaging independently predicted increased long-term mortality (P<0.001) and lower rates of documented aortic events (P=0.003). Kaplan-Meyer analysis showed a relationship of aortic diameter growth ≥0.5 cm per year with late death (P=0.041) and with late aortic events (P<0.001). However, rapid aortic growth did not relate to warfarin anticoagulation.

Conclusions: Warfarin anticoagulation is frequent in postsurgical AAAD and it is administered for vital indications. Warfarin anticoagulation does not relate to late mortality or to late aortic events. Rapid aortic growth predicts late mortality and late aortic events, but warfarin anticoagulation is not associated with aortic growth. Follow-up tomographic imaging is mandatory for long-term survival after surgical repair of AAAD.