What is the most appropriate next step in management for a patient with intermittent claudication and suspected peripheral arterial disease (PAD)?

Exercise Ankle-Brachial Index is the Most Appropriate Next Step for a Patient with Intermittent Claudication

For a patient with classic symptoms of intermittent claudication and an abnormal resting ankle-brachial index (ABI), the exercise ankle-brachial index is the most appropriate next diagnostic step to confirm peripheral arterial disease (PAD) and guide management decisions.

Clinical Presentation Analysis

• The patient presents with classic symptoms of intermittent claudication: left calf cramping pain that occurs after walking two blocks and resolves with rest, consistent with PAD 1
• Risk factors for PAD include:
  • Age 65 years 1
  • History of hypertension and type II diabetes mellitus 1, 2
  • Former smoker (quit 5 years ago) 1
  • Family history of thrombotic disease (mother with PE) 1
• Physical examination reveals:
  • Left ankle blood pressure of 210/150 mmHg with left arm blood pressure of 140/85 mmHg, suggesting an abnormal ABI 1
  • No evidence of critical limb ischemia (no swelling, redness, or skin breakdown) 1

Diagnostic Approach for Intermittent Claudication

Initial Assessment with ABI

• ABI is the recommended first-line non-invasive test for screening and diagnosis of PAD 1
• The patient's ABI appears abnormal, with ankle pressure significantly higher than brachial pressure, suggesting non-compressible vessels (arterial calcification) 3
• In patients with diabetes, arterial calcification can lead to falsely elevated ABI values (>1.4), making resting ABI less reliable 3, 2

Why Exercise ABI is the Most Appropriate Next Step

• When resting ABI is abnormal or non-diagnostic (as in this case with likely calcified vessels), exercise ABI testing is recommended to confirm the diagnosis of PAD 1, 3
• Exercise ABI can unmask PAD in patients with normal or non-diagnostic resting ABI values 3
• Research shows that in patients with symptoms of claudication but normal resting ABI, 31% will have an abnormal post-exercise ABI, confirming PAD 3

Why Other Options Are Less Appropriate:

1. Toe-brachial index:

   • While useful in patients with non-compressible vessels, this is typically used when exercise testing cannot be performed 1
   • Not the first choice when exercise testing is feasible in a patient with classic claudication symptoms 1

2. Doppler ultrasound:

   • Indicated as a first-line imaging method to confirm PAD lesions after hemodynamic testing (ABI) has established the diagnosis 1
   • Should be used after functional assessment with exercise ABI in this case 1

3. CT angiogram:

   • More invasive with contrast exposure and radiation risks 1
   • Should be reserved for anatomical characterization after PAD is confirmed functionally 1
   • Guidelines recommend that "arterial imaging is not indicated for patients with a normal postexercise ABI" 1

4. MR arteriography:

   • More expensive and less readily available than exercise ABI 1
   • Should be used for anatomical characterization after PAD is confirmed functionally 1
   • Not appropriate as the next immediate step 1

Management Implications

• After confirming PAD with exercise ABI, management should include:
  • Comprehensive risk factor modification (diabetes, hypertension, smoking cessation reinforcement) 1
  • Antiplatelet therapy to reduce cardiovascular risk 1
  • Supervised exercise training (30-45 minutes, at least 3 times weekly for minimum 12 weeks) 1
  • Consideration of pharmacotherapy with cilostazol to improve walking distance 1
  • Revascularization only if significant disability persists despite conservative management 1

Conclusion

Based on the clinical presentation of classic intermittent claudication with likely non-compressible vessels (abnormal resting ABI), the exercise ankle-brachial index is the most appropriate next diagnostic step to confirm PAD and guide management decisions.