Calf perfusion wave upstroke analysis can detect and grade the severity of above-knee peripheral artery disease, and classify patients based on their disease location.

Introduction: The AHA guidelines for PAD management emphasize treatment strategies based on patients` functional status and atherosclerotic lesion morphology. Above-knee (AK) lesions are associated with worse limb and cardiovascular outcomes than Infra-popliteal (IP) lesions. In patients with isolated AK disease, we previously showed that prolonged upstroke of the impedance-plethysmography perfusion-wave (I-PW), quantified using the ‘Perfusion Deficit Index` (PDI), can accurately detect AK stenosis. This study aimed to evaluate the ability of I-PW to differentiate between severe AK or IP lesions and patent AK arteries.

Methods: A Helsinki approved clinical trial measured I-PW from the calf of PAD patients. The I-PWs were derived from the cardiac cycle blood volume modulations of the calf. We analyzed the I-PWs from patients with AK and IP lesions before and after revascularization procedures.

Results: Forty-three patients were recruited: nineteen with prolonged PDI and isolated AK stenosis (Class-A), ten with prolonged PDI and combined AK and IP stenosis (Class-B) and fourteen with short PDI and combined AK and IP stenosis (Class-C). Class-C patients were older than Classes-A and B patients (P<0.01), had relatively more diabetes and hypertension, and suffered from a more severe distal IP disease (P<0.001). After revascularization, Classes A and B patients with patent AK arteries showed significantly shorter PDI (P < 0.01), while PDI remained short in Class C patients. A decision tree model using the ABI and PDI as variables was able to accurately classify patients to Classes-A+B, C, and patent AK arteries in 88%, 57% and 97% of the cases, with a total accuracy of 86%.

Conclusions: The PDI of the I-PW can accurately detect significant AK stenosis and improvement after revascularization. It can also aid in differentiating patients based on disease location, which may aid in treatment strategies.