A 68-year-old man with a 40-year smoking history and poorly controlled diabetes (HbA1c 9.2%) presents with a 3-month history of progressive pain in his right calf during walking that resolves after 10–15 minutes of rest. On examination, the right foot is cool to touch, femoral pulses are palpable bilaterally, but right popliteal and pedal pulses are absent. Ankle-brachial index (ABI) on the right is 0.62. Which of the following is the most appropriate next step in management?