Low functional capacity in peripheral artery disease is associated with increased platelet activity and...

Low functional capacity is an independent risk factor for cardiovascular (CV) events. Regular physical activity may reduce CV risk through suppression of inflammation and reduced platelet activity. We aimed to investigate the association of functional capacity quantified by the validated Duke Activity Status Index (DASI) with platelet activity and incident major adverse CV and limb events (MACLE) in individuals with peripheral artery disease (PAD) undergoing lower extremity revascularization (LER).

Light transmission aggregometry and platelet RNAseq were performed on specimens isolated from men and women prior to LER. Functional capacity was assessed using DASI. Prospective follow-up occurred at 1, 6, 12, and every 6 months following the LER. Subjects were separated into tertiles of DASI scores and incidence rates for MACLE were calculated using log-rank tests. Mediation analysis using linear regression fit with least squares was performed to test whether DASI exerted its effect on MACLE via platelet aggregation.

281 patients completed the DASI questionnaire with scores ranging from 0.0 to 50.2 (bottom tertile: 0.0-9.95). Mean age was 74.4 ± 10.9 years and 32.4 % were female. During a median follow-up of 19 months, 163 (58.0 %) participants experienced a MACLE. After correction for demographics and CV risk factors, individuals in the lowest DASI tertile experienced significantly more MACLE than participants in other tertiles. The association between DASI and MACLE was consistent across multiple subgroups stratified by age, sex, body mass index, antiplatelet therapy, and clinical comorbidities. Mediation analyses suggested higher platelet aggregation to epinephrine in the bottom DASI tertile mediated 24.7 % [5.0 %, 103 %] of increased MACLE risk. Platelet mRNA demonstrated upregulation of inflammation pathways in the most sedentary individuals (lowest DASI tertile).

Patients with PAD and low functional capacity have increased platelet activity and high incidence of MACLE. Our data suggest that elevated platelet aggregation mediates one-quarter of the MACLE risk in persons with low functional capacity undergoing LER. Our findings support a potential platelet-mediated mechanism for improved CV outcomes associated with regular physical activity.