Temporal variability in the antiplatelet effects of clopidogrel and aspirin after elective drug-eluting stent implantation. An ADAPT-DES substudy

Low on-clopidogrel ADP- and TRAP-6-induced platelet aggregation in patients with atrial fibrillation undergoing percutaneous coronary intervention: an observational pilot study

High on-clopidogrel platelet reactivity (HPR) associates with ischemic risk in patients after percutaneous intervention (PCI). This study aimed to evaluate the association of HPR as assessed by multiple electrode aggregometry (MEA) with ischemic, thromboembolic, and bleeding risk in patients with atrial fibrillation (AF) undergoing PCI. Patients with AF and an indication for oral anticoagulation (OAC) were included in this prospective cohort study on day 1-3 after PCI. Platelet aggregation [U] was analyzed by MEA. HPR and low platelet reactivity (LPR) were defined as ADP-induced aggregation ≥ 46 U and ≤ 18 U, respectively. TRAP-6-induced aggregation reference was 94-156 U. The primary outcome was time to all-cause death, myocardial infarction, or stroke at 6 months. The secondary outcome was time to non-major clinically relevant bleedings or major bleedings. 159 patients were enrolled between May 2020 and May 2021. The median age was 78 years (interquartile range 72-82) and 111 (70%) were male. Median ADP- and TRAP-induced aggregation were 12 (6-17) and 49 (35-68) U, respectively. 147 (93%) patients had a low overall aggregability. HPR was detected in 2 patients (1%) and 125 (79%) had LPR. ADP-induced aggregation did not significantly associate with the primary outcome (r = 0.081, p = 0.309) but correlated inversely with bleeding risk (r = - 0.201, p = 0.011). HPR status as assessed by MEA among patients with AF after PCI was rare and overall aggregability was low. Conventional cut-off values for HPR might be inappropriate for these patients. ADP-induced aggregation might be helpful to identify patients at risk for bleeding.

High-on-treatment platelet reactivity predicts adverse outcome after carotid artery stenting: A prospective study

BACKGROUND AND PURPOSE

High-on-treatment platelet reactivity (HTPR) has been established as a predictor of major adverse cardiovascular events (MACE) in patients undergoing percutaneous coronary interventions on dual antiplatelet therapy (DAPT), but no data are available on its predictive value in patients on DAPT after carotid artery stenting (CAS). We aimed to evaluate the possible association between HTPR in patients on aspirin plus clopidogrel therapy after CAS and subsequent MACE.

METHODS

All consecutive patients treated with CAS in a single institution were enrolled in a prospective clinical study. HTPR was evaluated with 5 different laboratory assays carried out just before CAS. MACE incidence (cerebral ischemia, myocardial infarction, stent thrombosis, acute limb ischemia and vascular death) was evaluated at 30 days and thereafter at yearly visits.

RESULTS

A total of 300 patients were enrolled in the study, and eight were then excluded because blood samples resulted unsuitable for the laboratory testing or CAS aborted for technical problems. Median follow-up was 5.8 years and during this period 47 MACE occurred. HTPR detected by multiplate electronic aggregometry (MEA) and the VASP phosphorylation assay (VASP) were associated with a significantly enhanced risk of MACE (p = 0.048 and p = 0.038, respectively). However, HTPR to three tests (HTPR3) was more strongly predictive of increased risk of a vascular event at follow up (p = 0.005) at bivariate analysis and also at Cox regression multivariate analysis (p = 0.002).

CONCLUSIONS

HTPR to three different assays (mainly to VASP + PFA P2Y+ VerifyNow) in patients on DAPT after CAS has predictive value for subsequent MACE. Prospective studies to assess whether platelet function testing-guided antiplatelet therapy is superior to standard DAPT in patient undergoing CAS should be considered.

Endothelial Shear Stress and Platelet FcγRIIa Expression in Intracranial Atherosclerotic Disease

Intracranial atherosclerotic disease (ICAD) has been characterized by the degree of arterial stenosis and downstream hypoperfusion, yet microscopic derangements of endothelial shear stress at the luminal wall may be key determinants of plaque growth, vascular remodeling and thrombosis that culminate in recurrent stroke. Platelet interactions have similarly been a principal focus of treatment, however, the mechanistic basis of anti-platelet strategies is largely extrapolated rather than directly investigated in ICAD. Platelet FcγRIIa expression has been identified as a potent risk factor in cardiovascular disease, as elevated expression markedly increases the risk of recurrent events. Differential activation of the platelet FcγRIIa receptor may also explain the variable response of individual patients to anti-platelet medications. We review existing data on endothelial shear stress and potential interactions with the platelet FcγRIIa receptor that may alter the evolving impact of ICAD, based on local pathophysiology at the site of arterial stenosis. Current methods for quantification of endothelial shear stress and platelet activation are described, including tools that may be readily adapted to the clinical realm for further understanding of ICAD.

Variation in platelet expression of FcγRIIa after myocardial infarction

FcγRIIa amplifies platelet activation and greater platelet expression of FcγRIIa identifies patients at greater risk of subsequent cardiovascular events. Thus, platelet expression of FcγRIIa may be useful to guide therapy. Because platelet function tests are impacted by preparative procedures and substantial intra-individual variability, we examined the impact of these factors on platelet expression of FcγRIIa in blood from healthy subjects and in patients after myocardial infarction (MI). Platelet expression of FcγRIIa was quantified with the use of flow cytometry. Blood was taken from healthy subjects and 114 patients after a MI in whom platelet expression of FcγRIIa was quantified before discharge and at 6 ± 1 months. Neither anticoagulants nor the antiplatelet agent cangrelor changed platelet expression of FcγRIIa. Intra-individual variation in platelet FcγRIIa expression was 8.5% ± 5% over the course of 1 month in healthy subjects. Platelet FcγRIIa expression was within 20% of the baseline value after 6 months in 71% of patients after MI. In summary, because FcγRIIa is a protein on the surface of platelets, assay conditions and antiplatelet agents do not change expression. Intra-individual variability in platelet expression of FcγRIIa is modest. Accordingly, platelet expression of FcγRIIa is a marker of increased platelet reactivity that can be reliably and repeatedly measured.Clinical Trial Registration: NCT02505217.

Temporal Variability of Platelet Reactivity in Patients Treated with Clopidogrel or Ticagrelor

Background and Objectives

The degree of antiplatelet response to P2Y12 inhibitors has been associated with clinical outcomes. The aim of this study was to test the variability of platelet reactivity over time among patients treated with clopidogrel or ticagrelor.

Methods

A single-center cohort of acute coronary syndrome patients that underwent percutaneous coronary intervention (PCI) was analyzed. Platelet reactivity was measured at baseline, 48 hours after PCI, 1 month, and 6 months after clopidogrel (n=79) or ticagrelor (n=93) treatment. High on-treatment platelet reactivity (HPR) was defined as ≥47 U, assessed by multiple electrode platelet aggregometry.

Results

Platelet reactivity in the clopidogrel group increased over time, 38.2±21.7 U at 48 hours, 41.4±22.3 U at 1 month, and 44.7±25.5 U at 6 months (p=0.018, 48 hours to 6 months). However, platelet reactivity in the ticagrelor group was not significantly changed, 21.4±12.6 U at 48 hours, 20.0±12.2 U at 1 month, and 22.8±13.8 U at 6 months (p=0.392). A platelet reactivity change over time of more than 20U was found in 67.1% of the patients with clopidogrel group and 34.4% of ticagrelor group (p<0.001). Between 48 hours and 6 months, 43% of patients changed their responder status in the clopidogrel group, and 13% in the ticagrelor group (p<0.001).

Conclusions

Although ticagrelor treatment resulted in less temporal variability of platelet reactivity than clopidogrel treatment in terms of HPR, platelet reactivity varied over time in a significant proportion of patients.

Early time course of major bleeding on antiplatelet therapy after TIA or ischemic stroke

Objective

To study the early time course of major bleeding and its subtypes in patients with cerebral ischemia on dual and single antiplatelet therapy.

Methods

We performed a post hoc analysis on individual patient data from 6 randomized clinical trials (Clopidogrel Versus Aspirin in Patients at Risk of Ischaemic Events [CAPRIE], Second European Stroke Prevention Study [ESPS-2], Management of Atherothrombosis With Clopidogrel in High-Risk Patients [MATCH], Clopidogrel for High Atherothrombotic Risk and Ischemic Stabilization, Management, and Avoidance [CHARISMA], European/Australasian Stroke Prevention in Reversible Ischaemia Trial [ESPRIT], and Prevention Regimen for Effectively Avoiding Second Strokes [PRoFESS]) including 45,195 patients with a TIA or noncardioembolic ischemic stroke. We studied incidence rates of bleeding per antiplatelet regimen stratified by time from randomization (≤30, 31–90, 91–180, 181–365, >365 days). We calculated incidence rates per trial and pooled estimates with random-effects meta-analysis. We performed Poisson regression to assess differences between time periods with adjustment for age and sex.

Results

The incidence of major bleeding on aspirin plus clopidogrel and aspirin plus -dipyridamole was highest in the first 30 days, 5.8 and 4.9 per 100 person-years, respectively, and was significantly higher than at 31 to 90 days (rate ratio 1.98, 95% confidence interval 1.16–3.40 for aspirin plus clopidogrel; rate ratio 1.94, 95% confidence interval 1.24–3.03 for aspirin plus dipyridamole). Incidence rates on aspirin and clopidogrel monotherapy were 2.8 and 2.5 per 100 person-years, respectively, in the first 30 days, with no significant change over time. The time course was similar for gastrointestinal bleeds. There was no early excess of intracranial hemorrhage in patients on either dual or single antiplatelet therapy.

Conclusion

Dual antiplatelet therapy is associated with high early risks of major and gastrointestinal bleeding that decline after the first month in trial cohorts.

Impact of Aspirin and Clopidogrel Hyporesponsiveness in Patients Treated With Drug-Eluting Stents: 2-Year Results of a Prospective, Multicenter Registry Study

OBJECTIVES

In this analysis of 2-year outcomes in the ADAPT-DES (Assessment of Dual AntiPlatelet Therapy with Drug-Eluting Stents) study, the authors sought to examine the independent associations between platelet reactivity to both aspirin and clopidogrel and subsequent outcomes.

BACKGROUND

The relationship between platelet reactivity and long-term adverse events following implantation of drug-eluting stents (DES) has been incompletely characterized.

METHODS

The ADAPT-DES study was a multicenter registry of patients undergoing routine platelet function testing following percutaneous coronary intervention with DES. The primary study endpoint was definite or probable stent thrombosis (ST); other endpoints were all-cause mortality, myocardial infarction, and clinically relevant bleeding.

RESULTS

A total of 8,582 patients were enrolled between 2008 and 2010; 46.3% of patients were on dual antiplatelet therapy at 2 years without discontinuation. At 2 years, definite or probable ST occurred in 92 patients (1.07%). In patients treated with dual antiplatelet therapy continuously for 2 years, high platelet reactivity on clopidogrel was independently associated with definite or probable ST (adjusted hazard ratio [HR]: 2.16; 95% confidence interval [CI]: 1.27 to 3.67; p = 0.003), myocardial infarction (adjusted HR: 1.35; 95% CI: 1.05 to 1.74; p = 0.02), freedom from clinically relevant bleeding (adjusted HR: 0.74; 95% CI: 0.62 to 0.90; p = 0.002), and all-cause mortality (adjusted HR: 1.36; 95% CI: 1.01 to 1.85; p = 0.04). Between years 1 and 2, high platelet reactivity was not associated with the very late ST and in patients on aspirin monotherapy, aspirin hyporesponsiveness was not associated with adverse outcomes.

CONCLUSIONS

The present study confirms the strong relationship of high platelet reactivity on clopidogrel to 2-year ischemic and bleeding outcomes after DES. The majority of stent-related events occurred within the first year.