False elevation of ABPI is seen in:
Ref. Sabiston Textbook of Surgery. Pg. 497
 
The ankle-brachial pressure index (ABPI) is the ratio of systolic pressure at the ankle to that in the arm .
The higher of the pressures in the dorsalis pedis and the posterior tibial arteries serves as the numerator ,with the higher systolic pressures between the brachialis serving as the denominator .

Resting ABPI is normally about 1 ,
<0.9 indicated some degree of arterial obstruction
<0.3 suggests imminent necrosis

# Artefacts are due especially due to calcified arteries, which are often incompressible and lead to a falsely high pressure or ABPI result ,especially in diabetics.
DVT
Acute limb ischemia
Chronic Venous insufficiency
Calcified vessel walls