- Ankle brachial index (ABI) < 0.90 in at least one extremity, or if Ankle brachial index (ABI)is ≥ 0.90 to ≤ 1.0, a reduction of at least 20% in Ankle brachial index (ABI), in at least one extremity, when measured within 1 minute after claudication-limiting treadmill testing. If the subject has non-compressible arteries then a toe brachial index (TBI) < 0.70 is required in at least one extremity.