Evaluation of aspirin's effect on platelet function early after coronary artery bypass grafting

Area of Science:

• Cardiology
• Pharmacology
• Vascular Surgery

Background:

• Aspirin therapy is standard for reducing mortality and ischemic complications after coronary artery bypass grafting (CABG).
• However, the efficacy of oral aspirin in achieving adequate platelet inhibition during the early postoperative period after CABG remains incompletely understood.

Purpose of the Study:

• To assess the pharmacologic effect and efficacy of aspirin on platelet function in the initial postoperative days following CABG.
• To utilize specific laboratory tests to evaluate aspirin's effectiveness in this critical early phase.

Main Methods:

• A prospective study involving 30 patients undergoing CABG at a single cardiac surgery center.
• Postoperative aspirin efficacy (200 mg/d) was evaluated using serum thromboxane B2 (TxB2) suppression and arachidonic acid-induced platelet aggregometry (MULTIPLATE analyzer).
• Laboratory samples were collected preoperatively and on postoperative days 1 through 5.

Main Results:

• Serum TxB2 inhibition greater than 90% was not achieved until postoperative day 5 in 55% of patients.
• Effective platelet inhibition, defined by MULTIPLATE analyzer values below 300 AU*min, was only reached by 34% of patients on day 5.
• Both key laboratory markers indicated impaired aspirin efficacy in the early postoperative period after CABG.

Conclusions:

• Aspirin's ability to inhibit thromboxane B2 production and platelet aggregation is significantly impaired in the first few days after CABG.
• These findings suggest that current aspirin dosing may be insufficient for optimal early antiplatelet effect in this patient population.
• A more effective antiplatelet strategy could potentially enhance early graft patency and improve clinical outcomes following CABG.