Scientific summary

The IMPROVE aneurysm trial Immediate Management of the Patient with Rupture: Open Versus Endovascular repair

Trial Design


To compare the mortality from ruptured abdominal aortic aneurysm (AAA) in patients treated by an endovascular first strategy versus the conventional treatment of immediate open repair.


Specialist vascular centres credentialed for emergency endovascular AAA repair


Initial management of patients with suspected ruptured AAA with a fluid restriction protocol. When the in-hospital clinical diagnosis of ruptured AAA has been established, patients will be randomised to either an endovascular first strategy or to immediate open surgical repair. Patients randomised to an endovascular first strategy will be sent for immediate CT scan to determine their anatomical suitability for endovascular repair (approximately 60% patients will be suitable). Suitable patients will then undergo immediate endovascular repair and the remainder open repair.

Outcome measures:

The primary outcome is 30-day mortality. Secondary outcome measures include 24h, in-hospital and 1y mortality, complications and morbidities associated with the two treatment strategies as well as quality of life, costs and cost-effectiveness.

Size of the trial:

The trial plans to recruit 600 patients over a 27 month period, to provide 90% power to detect (as significant at 5%) a difference in 30-day mortality of 14%, with mortality estimated at 44.6% in the open repair group and 30.4% in the EVAR first strategy group.