I have an ankle‑brachial index of 1.0 and no leg symptoms; what does this indicate and what management or follow‑up is recommended given my cardiovascular risk factors (e.g., hypertension, hyperlipidaemia, diabetes, smoking)?

ABI of 1.0 in an Asymptomatic Patient with Cardiovascular Risk Factors

An ankle-brachial index of 1.0 is technically within the normal range (0.91–1.40), but in the context of multiple cardiovascular risk factors—especially diabetes—you should not rely on this single measurement alone and must obtain a toe-brachial index (TBI) to rule out masked peripheral arterial disease from arterial calcification. 1

Understanding Your ABI Value

Your ABI of 1.0 falls into what the American Heart Association considers a "borderline" zone (0.91–0.99), which warrants additional evaluation rather than simple reassurance. 1 While values between 0.91 and 1.40 are traditionally labeled "normal," the optimal cardiovascular risk range is actually 1.11–1.40, and your value sits below this. 1

Critical Limitation in High-Risk Patients

The most important caveat: if you have diabetes, your ABI of 1.0 is unreliable and potentially falsely reassuring. 1, 2 Medial arterial calcification (Mönckeberg sclerosis) is highly prevalent in diabetic patients and causes arteries to become stiff and non-compressible, producing falsely normal or even elevated ABI readings despite significant underlying stenotic disease. 1, 3 Research demonstrates that up to 50% of patients with ABI >1.40 have coexisting peripheral arterial disease that the ABI completely misses. 3

Mandatory Next Steps

For Patients with Diabetes

You must obtain a toe-brachial index immediately, regardless of your ABI result. 1, 4 The American College of Cardiology and American Heart Association recommend TBI in all diabetic patients because digital arteries are rarely affected by medial calcification, making TBI far more reliable than ABI. 1

• TBI <0.70–0.75 confirms peripheral arterial disease 1, 4
• TBI should be performed even when ABI appears normal because arterial calcification can mask significant ischemia 1

For Patients with Other Risk Factors (Hypertension, Hyperlipidemia, Smoking)

Even without diabetes, your constellation of cardiovascular risk factors places you at elevated risk for both peripheral arterial disease and cardiovascular events. 5, 6

If you develop any exertional leg symptoms in the future—even with your current ABI of 1.0—you require exercise treadmill ABI testing. 1 A post-exercise ankle pressure decrease >30 mmHg or ABI decrease >20% confirms PAD even when resting ABI appears normal. 1

Cardiovascular Risk Management

Your ABI of 1.0, while not diagnostic of PAD, still identifies you as someone requiring aggressive cardiovascular risk factor modification. 5 The relationship between ABI and cardiovascular outcomes follows a reverse J-shaped curve, with the lowest mortality risk in the 1.11–1.40 range. 1 Your value of 1.0 places you outside this optimal zone.

Mandatory Interventions

The American Heart Association and American College of Cardiology recommend the following for patients with your risk profile: 5, 4

• Statin therapy to achieve LDL-C <55 mg/dL or at least 50% reduction 7
• Smoking cessation support if currently smoking (smoking is independently associated with low ABI) 5
• Blood pressure control (hypertension is independently associated with PAD, with adjusted odds ratio 3.20) 6
• Glycemic control if diabetic 4
• Consider antiplatelet therapy (low-dose aspirin or clopidogrel) for cardiovascular risk reduction 4, 7

Follow-Up Protocol

Annual ABI Surveillance

You should have bilateral ABI measurements repeated annually given your borderline value and cardiovascular risk factors. 1 The American Heart Association emphasizes that PAD may not progress symmetrically in both limbs, so both legs must be measured at each visit. 5

When to Escalate Testing

Proceed immediately to additional vascular testing if: 1, 4

• You develop any exertional leg symptoms (claudication, leg fatigue)
• You develop non-healing wounds on your feet or legs
• Your ABI drops to ≤0.90 on follow-up measurement
• Your ABI rises to >1.40 (indicating arterial calcification)
• You have diabetes and have not yet had TBI measured

Common Pitfalls to Avoid

Never assume peripheral arterial disease is absent based solely on a single resting ABI measurement of 1.0, especially if you have diabetes. 1 The sensitivity of ABI is significantly lower in diabetic patients compared to the general population, particularly when neuropathy or chronic kidney disease coexist. 1

Never rely on palpable pulses alone—even skilled examiners can detect pulses despite significant ischemia. 4

Never delay obtaining TBI if you are diabetic—a normal ABI in diabetes does not reliably exclude PAD and requires additional vascular testing. 1

Summary Algorithm

1. If diabetic: Obtain TBI immediately regardless of ABI result 1
2. If non-diabetic with multiple risk factors: Implement aggressive cardiovascular risk reduction and annual ABI surveillance 5, 1
3. If any exertional leg symptoms develop: Obtain exercise ABI testing 1
4. If ABI drops to ≤0.90 or rises to >1.40 on follow-up: Proceed to duplex ultrasound or other anatomic imaging 1, 7

Your ABI of 1.0 is not a "free pass"—it represents a borderline finding in the context of significant cardiovascular risk factors that demands both additional testing (especially if diabetic) and aggressive risk factor modification to prevent future cardiovascular events and limb complications.