Role of Aspirin Resistance, Mechanical Factors and Inflammation on Early Saphenous Vein Graft Thrombosis After CABG

Objectives: This study was carried out to determine the role of pre-operative and transient aspirin resistance in the formation of early saphenous vein graft (SVG) thrombosis six weeks after coronary artery bypass graft (CABG) surgery and to analyze the other factors, such as mechanical and inflammation factors, that are also suspected of contributing to the formation of early thrombosis.

Methods: Pre- and post-operative blood samples were taken from 99 subjects, whom 74 patients were undergoing elective on-pump CABG and receiving aspirin as monotherapy, for evaluation of inflammation parameters and the state of aspirin resistance using a Platelet Function Analyzer-200 (PFA-200). Transit time flow measurements (TTFM) were performed intra-operatively to determine mechanical factors. Multi-sliced computed tomography (MSCT) was done six weeks after surgery to determine the patency of the vein grafts.

Result: In the 222 vein conduits, aspirin resistance was related to early vein graft failure due to thrombosis (p < 0.001; relative risk (RR) = 3.69). The massive increase of interleukin 6 (IL-6) levels after surgery were related to the existence of post-operative transient aspirin resistance (p < 0.001). Transient aspirin resistance (IL-6 > 122.5) was associated with early graft failure (p = 0.029; RR = 8.6) compared to the aspirin-sensitive group (IL-6 > 122.5).

Conclusion: Aspirin resistance plays a primary role in early vein graft thrombosis. Transient aspirin resistance accompanied by an increase of inflammation factor (IL-6) significantly increases the risk of early vein graft thrombosis after CABG.