INvestigation of STEnt grafts in patients with type B Aortic Dissection: design of the INSTEAD trial--a prospective, multicenter, European randomized trial.

Purpose: This study describes the design of an ongoing randomized trial initiated to compare the 2-year outcome of uncomplicated type B aortic dissection when treated by endovascular implantation of a Medtronic Talent stent graft adjunctive to best medical treatment versus best medical treatment alone.

Methods: Patients older than 18 years with type B aortic dissection as diagnosed by computed tomography or magnetic resonance angiography are randomized to either a thoracic aortic endoprosthesis and antihypertensive treatment, called "stent grafting," or a tailored antihypertensive treatment, called "medical treatment." Only patients in a clinically stable condition and without spontaneous thrombosis of the false lumen after 14 days of the index dissection are considered eligible for study inclusion.

Results: Primary outcome measure is all-cause mortality. Secondary outcome variables include conversion to stent and/or surgery, induced thrombosis of the false lumen, cardiovascular morbidity, aortic expansion (>5 mm/y of maximum diameter including true and false lumina), quality of life, and length of intensive care unit and hospital stay. The study design calls for 136 patients to be randomized and monitored for 24 months.

Conclusions: The INSTEAD trial is the first randomized trial investigating the role of endoluminal treatment of uncomplicated type B aortic dissection. By the end of December 2004, 125 patients were randomized, accounting for 92% of the target. Final results of the INSTEAD trial should be available in 2006.