Posttreatment platelet reactivity on clopidogrel is associated with the risk of adverse events after off-pump coronary artery bypass

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.

Bilateral versus Single Internal Thoracic Artery Grafting Strategies Supplemented by Radial Artery Grafting

PURPOSE

It is unclear if a second or third arterial graft can improve clinical outcomes in coronary artery bypass graft surgery. We compared the outcomes of bilateral internal thoracic artery (BITA) plus radial artery (RA) grafting versus left internal thoracic artery (LITA) plus RA grafting after off-pump coronary artery bypass grafting.

MATERIALS AND METHODS

Between January 2009 and December 2020, a total of 3007 patients with three-vessel coronary artery disease who underwent off-pump coronary artery bypass were analyzed. Among them, 971 patients received total arterial grafting using LITA. We divided the patients into two groups [group A, BITA+RA grafting (n=227) and group B, LITA+RA grafting (n=744)], and compared the survival and major adverse cardiac and cerebrovascular event (MACCE) rates between the two groups at 10 years.

RESULTS

After risk adjustment with inverse probability treatment weighting methods, the freedom from all-cause mortality was 93.1% and 88.3% in groups A and B, respectively (p=0.140). The freedom from MACCE rates were 68.3% and 89.0%, respectively (p<0.0001). LITA plus RA grafting [hazard ratio (HR): 1.3, 95% confidence interval (CI): 1.05-2.37, p=0.025] and incomplete revascularization (HR 1.2, 95% CI: 0.70-2.15, p=0.046) were significant risk factors for MACCEs in multivariable Cox regression analysis.

CONCLUSION

The rates of MACCEs were lower with LITA plus RA grafting than with BITA plus RA grafting in total arterial revascularization. Furthermore, complete revascularization improved long-term outcomes following total arterial grafting.

Predicting ischaemic events using platelet reactivity in patients receiving clopidogrel: Indirect meta-comparison among VerifyNow, light transmission aggregometry and thromboelastography

The present study compared performances of the three major methods used for assessing platelet reactivity (PR)-VerifyNow, light transmission aggregometry (LTA) and thromboelastography (TEG)-to predict ischaemic events in patients receiving clopidogrel. PubMed, EMBASE and the Cochrane Library were searched from their inception to April 2019 for prospective studies that examined PR using VerifyNow, LTA or TEG and the incidence of ischaemic events. The investigated diagnostic indices include sensitivity, specificity, positive (PLR) and negative likelihood ratio (NLR), diagnostic odds ratio and area under the receiver operating characteristic curves (AUC) of VerifyNow, LTA and TEG, respectively. A total of 26 prospective studies involving 22 185 patients were included in the analysis. The pooled AUC was 0.71 (95% CI: 0.67-0.75) for VerifyNow, 0.60 (95% CI: 0.55-0.64) for LTA and 0.81 (95% CI: 0.77-0.84) for TEG. Results of indirect comparisons indicated the AUC of VerifyNow was higher than that of LTA (1.18, 95% CI: 1.08-1.30) and lower than that of TEG (0.88, 95% CI: 0.82-0.94). TEG outperformed the other two methods for assessing PR in all predictive measures, including sensitivity, specificity, PLR and NLR. Despite a lack of studies that directly compared the three methods, our findings suggest that TEG should be recommended.

Predictive Value of Methods Measuring Platelet Activation for Ischemic Events in Patients Receiving Clopidogrel: A Systematic Review and Meta-analysis

This study investigates the efficiency and predictive value of light-transmission aggregometry (LTA), vasodilator-stimulated phosphoprotein (VASP) and VerifyNow for ischemia in patients undergoing percutaneous coronary intervention (PCI). Studies that used LTA, VASP or VerifyNow to predict ischemia were included, and their quality and efficiency were analyzed using Review Manager 5.3. The sensitivity and specificity of subgroup studies based on the outcome, cut-off value, and follow-up days were calculated and the summary ROC (sROC) curves were compared after having been fitted. Thirty-one studies including a total of 17,314 participants were analyzed. LTA, VASP and VerifyNow presented a considerable efficiency in predicting ischemic clinical events. In the subgroup analysis, the sensitivities of LTA, VASP and VerifyNow in predicting cardiac death, all-cause death, myocardial infarction, stent thrombosis, stroke, and revascularization were 0.40/0.63/0.62, 0.47/0.56/0.39, 0.40/0.48/0.60, 0.44/0.58/0.70, 0.29/not applicable/0.60 and 0.44/0.57/0.37, respectively and the specificities of LTA, VASP, and VerifyNow were 0.85/0.48/0.63, 0.73/0.52/0.63, 0.74/0.55/0.64, 0.75/0.47/0.61, 0.72/not applicable/ 0.61, and 0.70/0.47/0.67, respectively. LTA showed a higher sensitivity in predicting the outcomes over six months than those within six months, while VerifyNow prediction sensitivity was found to be higher within six months. Meanwhile, VerifyNow showed no statistically significant higher AUC of sROC in comparison to LTA and VASP in predicting ischemic events in patients undergoing clopidogrel treatment. The cut-off values of LTA, VASP and VerifyNow were suggested to be 56%, 50% and 235 respectively according to our study.

Carotid Endarterectomy on Antiplatelet Agents in the Era of Point-of-Care Testing

OBJECTIVE

The safety of carotid endarterectomy in patients with a response to antiplatelet agents (aspirin and clopidogrel) confirmed by point-of-care testing is unknown. Thus, we sought to determine whether using point-of-care assessment of platelet inhibition reveals risk factors for operative complications or predicts clinical outcomes.

METHODS

We reviewed records of carotid endarterectomy patients treated from March 2013 to July 2015 to extract demographics, lesion characteristics, laboratory data, procedural complications, and follow-up. Administration of aspirin, clopidogrel, or therapeutic anticoagulation within 5 days before surgery was recorded.

RESULTS

We analyzed 79 patients with 86 lesions (mean age 70.9 ± 10.0 years). More patients with a P2Y12 reaction unit (PRU) <170 had neck hematomas (4/10, 40.0%) than those with a PRU ≥170 (2/9, 22.2%) (P = 0.63). Estimated blood loss ≥100 mL was more frequent among patients with PRU <170 (9/10, 90.0%) than among those with PRU ≥170 (5/9, 55.6%) (P = 0.09). Clopidogrel use, regardless of response, independently predicted neck hematoma in a logistic regression model, with increased odds of 8.5. Mean postoperative modified Rankin Scale scores did not differ statistically between clopidogrel users and nonusers at a mean follow-up of 108.5 ± 146.3 days (P = 0.27).

CONCLUSIONS

Clopidogrel use within 5 days of carotid endarterectomy independently predicted postoperative neck hematomas, most of which were managed conservatively. Patients with PRU <170 were more likely to have estimated blood loss ≥100 mL during surgery and surgery lasting ≥3 hours.

Development of a concept for a personalized approach in the perioperative antiplatelet therapy administration/discontinuation management based on multiple electrode aggregometry in patients undergoing coronary artery surgery

In patients undergoing coronary artery surgery, improvements in clinical outcomes currently rely on continued refinements of the surgical technique and modulation of adjuvant pharmacotherapy. Despite medical and technological advances, negligible rate of bleeding and ischemic events still persist necessitating further improvements in patient management. Platelet function testing (PFT) might play an important role in meticulous balancing between the risk of bleeding and thrombotic events. A suitable balance can be achieved by implementing a personalized, PFT based approach in antiplatelet therapy (APT) administration/discontinuation management. Despite emerging evidence on the widespread variability in platelet inhibitory response to APT, numerous PFT devices and heterogeneity in reporting study results hamper pooling of the evidence which in turn results with a lack of consensus in "on treatment" platelet reactivity associated with ischemic and bleeding events in perioperative phase. The literature on multiple electrode aggregometry (Multiplate(®); Roche Diagnostics, Mannheim, Germany) in coronary artery disease patients was reviewed systematically. Based on the evidence evaluating the relationship between "drug specific" PFT and bleeding or adverse ischemic events, we sought to define therapeutic window for the most commonly administered antiplatelet drugs such as aspirin (ASPI test) and adenosine-diphosphate receptor blockers (ADP test). Preoperatively, APT administration was primarily focused to avoid bleeding complications. ASPI test value of 20 AUC and ADP test value of <73 AUC were set as cut-off values that delineate bleeding tendency. Postoperatively, "therapeutic window" was set to avoid both bleeding and adverse ischemic events. Therapeutic ranges were as follows: 20 AUC < ASPItest ≤ 30 AUC and 19AUC < ADP ≤ 46AUC, respectively. This is the first attempt to define PFT based "therapeutic window" according to, perioperative APT administration/discontinuation management would be targeted. It seems that the "one-size-fits-all" concept of perioperative APT administration management is outdated and further development of PFT based, personalized APT administration/discontinuation management is desirable. This concept therefore presents a possible step forward in patient care and provides a platform for further interventional trials whereby the impact of its application on clinical outcomes would be validated.

Assessment of steady-state clopidogrel reactivity by using platelet reactivity units

Platelet function testing is an important laboratory measure in clopidogrel treatment. We sought to investigate the stability of the reactivity of clopidogrel after 1 month of treatment. A prospective analysis was carried out using a matched study design to compare platelet reactivity units (PRUs) and platelet inhibition in clopidogrel-treated patients. Patients with various cardiac diseases were divided into 2 matched groups. The first group was treated on an inpatient acute basis, and the other group was treated on an outpatient chronic basis. PRU was measured 5 days after clopidogrel administration in the acute group and 1 month after chronic use for several cardiac indications in the second group. VerifyNow (Accumetrics) was used to detect platelet reactivity and calculate inhibition rates in response to clopidogrel. A total of 260 Saudi patients were enrolled, including 90 inpatients and 170 outpatients. A significant difference was observed in PRU (173.69 vs. 195) and percent inhibition (24.05% vs. 16.13%) between the outpatient and inpatient groups. Platelet function evolves over time and initial readings may not be constant.