Aspirin resistance in off-pump coronary artery bypass grafting

Antiplatelet Resistance in Coronary Artery Bypass Grafting: A Systematic Review

Background

This systematic review examines the occurrence and implications of resistance to primary antiplatelet agents, aspirin and clopidogrel, often utilised in patients undergoing coronary artery bypass grafting (CABG), alongside the methodologies for assessment of such resistance.

Methods

An extensive literature search across various databases such as PubMed, MEDLINE via Ovid, Embase, and Cochrane CENTRAL until May 2024 was conducted to identify studies evaluating antiplatelet resistance in on-pump and off-pump CABG patients. Following quality assessment, only high-quality studies were incorporated into this review.

Results

This review included 19 studies with 3,915 patients, four of which were randomised controlled trials and 15 were observational studies. Aspirin resistance incidence ranged from 11.0% to 51.5%, while clopidogrel resistance was 22%. Antiplatelet resistance, assessed through a wide variety of methods, was associated with a 13 times increase in the risk of vein graft occlusion and increased rates of mortality, myocardial infarction, and target vessel revascularisation in the case of clopidogrel resistance. The effect of cardiopulmonary bypass on antiplatelet resistance remains ambiguous.

Conclusion

The academic literature lacks a standardised definition for antiplatelet resistance. Assessment methodologies greatly vary, leading to noninterchangeable outcomes. While aspirin resistance has a conflicting overall significant impact on adverse outcomes, clopidogrel resistance correlates with poorer clinical outcomes.

Impact of diabetes mellitus on coagulation function before and after off-pump coronary artery bypass grafting

Background

This study aims to explore the influence of off-pump coronary artery bypass grafting (OPCABG) on coagulation function and the effects of diabetes on coagulation function during OPCABG.

Methods

Patients who met the inclusion and exclusion criteria were divided into two groups: diabetes mellitus (DM) and non-diabetes mellitus (NDM) groups. Thromboelastography (TEG) was tested at the following time points: T0, five days after aspirin and clopidogrel therapy, and before OPCABG; T1, returning to care unit after OPCABG; T2, 5 days after aspirin and clopidogrel therapy, and after OPCABG.

Results

A total of 56 patients were involved. There were no deaths, or no early postoperative thrombotic events and abnormal bleeding after OPCABG. Intra-group comparison: Compared with T0, the R and K value decreased, while the α angle and MA value increased at T1 and T2, in both groups (P<0.05). A significantly statistical difference was found in the multiple comparison at T0, T1 and T2 (P<0.05). The results are as follows: the R value decreased at T1 and increased at T2, but the value remained less than that at T0. After the OPCABG, the K value gradually decreased, while the MA value and α angle gradually increased. Comparison between groups: T1: the R values were lower in the DM group, when compared to the NDM group (t=3.611, P=0.001). The differences in the MA, K and α angle were not statistically significant. T0 and T2: there were no statistically difference in the R, MA, K, α angle and LY30 between the two groups (P>0.05).

Conclusions

The coagulation function of patients was at a hypercoagulable state at the early stage after OPCABG. The coagulation function was affected by diabetes at the day of OPCABG. However, there was no statistical difference after 5 days of aspirin and clopidogrel therapy following OPCABG.

[Influence of suture material on the development of postoperative complications in vascular surgery and their prevention]

Postoperative complications in vascular surgery may be partly provoked by suture material. Analysis of the mechanisms of these complications may be useful for their prevention. Mechanisms of suture-induced thrombosis and neointimal hyperplasia, possible strategies for prevention of postoperative complications including those allowing drug deliveries directly to the vascular anastomosis area are discussed in the article. According to the literature data, heparin is the most optimal drug for modifying suture material and prevention of thrombosis and neointimal hyperplasia. Heparin delivery to the vascular anastomosis site will reduce the risk of thrombosis by inhibiting the activity of thrombin. Complex of heparin and antithrombin III increases inhibitory effect of antithrombin against thrombin. In addition, heparin is able to reduce proliferation of vascular smooth muscle cells through inhibition of the synthesis of extracellular matrix proteases involved in migration and proliferation of cells. Thus, heparin delivery to the vascular injury site may be used to prevent thrombosis and myoproliferative response. Moreover, this strategy prevents complications associated with systemic administration of anticoagulants.

Aspirin resistance: current status and role of tailored therapy

Aspirin is integral in the primary and secondary prevention of coronary artery disease and acute coronary syndrome. Given the high clinical importance of aspirin in the management of coronary artery disease, much attention has been directed towards the concept of "aspirin resistance." Unfortunately, the term aspirin resistance is ill-defined in the literature, leading to a large variance in the reported prevalence of this phenomenon. In this review, the current understanding of aspirin resistance is discussed. Commonly used functional and diagnostic tests of platelet function, including their strengths and weakness, are reviewed. We next discuss several proposed mechanisms of aspirin resistance and special high-risk groups at risk for aspirin treatment failure. We then discuss optimal dosing and diagnostic strategies for those populations at risk for aspirin resistance with a focus on tailored aspirin therapy for high-risk groups. Finally, future topics of interest in the field of aspirin resistance are considered.