A 68-year-old male presents with a 4-month history of intermittent left calf pain. Ankle-brachial index (ABI) is 0.67 on the left and 0.91 on the right. He is enrolled in a supervised exercise program. Three months laterthe patient reports that despite adherence to the programhis symptoms have progressed. What is the most appropriate next step in management?
a) Initiation of antiplatelet therapy with aspirin
b) Referral for surgical revascularization
c) Duplex ultrasound or other imaging studies to assess for disease progression
d) Adjustment of exercise regimen to include more aggressive training
