Background: Patients with critical limb ischemia (CLI) have a high rate of adverse cardiovascular events, particularly when undergoing surgery. We sought to determine the effect of surgery and vascular disease on platelet and monocyte activation in vivo in patients with CLI.
Methods: An observational, cross-sectional study was performed at a tertiary referral hospital in the southeast of Scotland. Platelet and monocyte activation were measured in whole blood in patients with CLI scheduled for infrainguinal bypass and compared with matched healthy controls, patients with chronic intermittent claudication, patients with acute myocardial infarction, and those undergoing arthroplasty (n = 30 per group). Platelet and monocyte activation were quantified using flow cytometric assessment of platelet-monocyte aggregation, platelet P-selectin expression, platelet-derived microparticles, and monocyte CD40 and CD11b expression.
Results: Compared with those with intermittent claudication, subjects with CLI had increased platelet-monocyte aggregates (41.7% +/- 12.2% vs 32.6% +/- 8.5%, respectively), platelet microparticles (178.7 +/- 106.9 vs 116.9 +/- 53.4), and monocyte CD40 expression (70.0% +/- 12.2% vs 52.4% +/- 15.2%; P < .001 for all). Indeed, these levels were equivalent (P-selectin, 4.4% +/- 2.0% vs 4.9% +/- 2.2%; P > .05) or higher (platelet-monocyte aggregation, 41.7% +/- 12.2% vs 33.6% +/- 7.0%; P < .05; platelet microparticles, 178.7 +/- 106.9 vs 114.4 +/- 55.0/microL; P < .05) than in patients with acute myocardial infarction. All platelet and monocyte activation markers remained elevated throughout the perioperative period in patients with CLI (P < .01) but not those undergoing arthroplasty.
Conclusions: Patients undergoing surgery for CLI have the highest level of in vivo platelet and monocyte activation, and these persist throughout the perioperative period. Additional antiplatelet therapy may be of benefit in protecting vascular patients with more severe disease during this period of increased risk.