Plasma Biomarkers to Predict Cardiovascular Outcome in Patients With Peripheral Artery Disease: A Systematic Review and Meta-Analysis.

OBJECTIVE: Patients with lower extremity peripheral artery disease (PAD) are at increased risk of major adverse cardiovascular events. Numerous plasma biomarkers have been investigated in lower extremity PAD, but none are used for clinical risk assessment. We aimed to provide a comprehensive overview of biomarker testing in PAD as a first step to improve risk stratification. Approach and Results: A systematic literature review in MEDLINE/PubMed, Cochrane, and Embase was performed, identifying all studies investigating plasma biomarkers in association with cardiovascular events and mortality in lower extremity PAD. Forty-seven studies comprising 21 473 PAD patients met our criteria and were included. Effect estimates were provided by the studies based on a minimum follow-up of 1 year. Meta-analyses were performed by pooling studies per biomarker for each end point. Patients with increased high-sensitivity CRP (C-reactive protein) levels had a relative risk of 1.86 (1.48-2.33) for major adverse cardiovascular events and a relative risk of 3.49 (2.35-5.19) for mortality. Increased fibrinogen and d-dimer levels were associated with an increased relative risk of mortality of 2.08 (1.46-2.97) and 2.22 (1.24-3.98), respectively. Additionally, patients with increased NT-proBNP (N-terminal pro-B-type natriuretic peptide) and high-sensitivity cTnT (cardiac troponin T) levels were at an even higher risk of mortality with relative risks of 4.50 (2.98-6.81) and 3.33 (2.70-4.10), respectively. CONCLUSIONS: This systematic review identifies promising biomarkers representing different pathophysiological processes implicated in lower extremity PAD, including high-sensitivity CRP, neutrophil-lymphocyte ratio, fibrinogen, d-dimer, NT-proBNP, and high-sensitivity cTnT. Clinical implementation should be preceded by a management study to test the utility of a combination of these markers for individual risk stratification. Ultimately, this may contribute to tailored treatment and increased effectiveness of current treatment strategies in PAD.