Platelet activation in patients with peripheral artery disease from 43 sites: Assessment of samples transported by...

Platelet activation plays a key role in peripheral artery disease, but the relevant platelet activation mechanisms in chronic limb-threatening ischemia remain unclear. Moreover, multicenter studies of in vivo platelet activation remain difficult owing to methodological limitations. We report the feasibility of a novel method to measure in vivo platelet activation using samples sent via overnight mail. We hypothesized that platelet function would be measured reliably after overnight transport.

Peripheral venous blood was drawn from 190 participants with severe peripheral artery disease at 43 sites in BEST-CLI (Best Endovascular vs Best Surgical Therapy in Patients with Chronic Limb Ischemia) and shipped by Federal Express cold pack from study site locations within the continental United States to Vanderbilt University Medical Center from July 2017 to November 2019. Fifty-six volunteers with and without diabetes were recruited locally as time- and age-matched control subjects. Samples were collected using a platelet activation inhibitor. Markers of platelet activation, thromboxane B2, dilysyl-malondialdehyde (MDA), p-selectin, WEDE 15, and SPAN 12 were measured using liquid chromatography with tandem mass spectrometry and flow cytometry. The primary objective was to report baseline markers of platelet activation from samples sent by overnight mail compared with an age-matched population recruited locally without known atherosclerosis.

Compared with control subjects, patients from BEST-CLI were more likely to be male (72.6% vs 51.8%; P < .01), have prior atherosclerotic cardiovascular disease (22.1% vs 0%; P < .01), and be prescribed aspirin (69.4% vs 35.7%; P < .01) or clopidogrel (20.0% vs 0%; P < .01). Thromboxane B2 (0.5 vs 2.9 ng/mL; P < .01) and dilysyl-MDA (4.7 vs 9.7 ng/mg; P < .01) were significantly higher in BEST-CLI patients than control subjects and p-selectin (592.0 meaajpan fluorescent intensity vs 420.5 mean fluorescent intensity; P < .01) was lower. Levels of thromboxane B2 and dilysyl-MDA varied significantly and as expected across the range of antithrombotic treatment intensity (P < .01).

Measurement of platelet activation after sample shipment on cold pack is feasible and yields reliable results that correspond with locally obtained clinical values.