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Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

The aims of this study were to determine the effect of failed prior endovascular treatment (EV) on early and midterm outcomes of subsequent lower extremity open surgical (OS) bypass.', 'Patients undergoing infrainguinal bypass for critical limb ischemia (CLI) from January 2008 to December 2011 were retrospectively reviewed. The results after first-line bypass and bypass after failure of EV treatment were compared. A total of 213 patients (65.25% men; average age, 73.30 years) underwent bypass. OS patients were then divided into 2 groups: group 1 consisted of 138 patients who underwent primary OS for CLI without prior EV (control group) and group 2 consisted of 75 patients who had OS after a failed attempt at elective EV for peripheral vascular disease. Of the 213 bypass performed, 34% had a prior infrainguinal failed EV. The primary study end points were early and 1-year major amputations and graft occlusion. The secondary outcomes included early and 1-year mortality and the level of distal revascularization.', 'Secondary patency and limb salvage rates were significantly better in group 1 up to 1 year (99% vs. 86%; P < 0.001 at 1 month and 95% vs. 76%, P < 0.05 at 12 months, respectively).
Output:
Is endo first appropriate in some patients with critical limb ischemia because '' bridges are burned ''?