A 64-year-old woman comes to the physician for a 2-month history of tightness and pain in her thighs when she walks for extended periods of time. She has history of angina pectoris and hypertension. Current medications are lisinopril and atorvastatin. Vitals are: temperature 98.6 F, HR 72, RR 16, BP 145/90. Auscultation of the chest shows a 3/6 holosystolic murmur loudest at the apex. Which of the following is the next best step in management?
Ambulatory ECG monitoring
Ankle-brachial indices
Carotid duplex ultrasonography
Complete blood count
Dipyridamole-thallium stress test
