Tailored antiplatelet therapy to improve prognosis in patients exhibiting clopidogrel low-response prior to percutaneous coronary intervention for stable angina or non-ST elevation acute coronary syndrome

Current Strategies to Guide the Antiplatelet Therapy in Acute Coronary Syndromes

The role of antiplatelet therapy in patients with acute coronary syndromes is a moving target with considerable novelty in the last few years. The pathophysiological basis of the treatment depends on platelet biology and physiology, and the interplay between these aspects and clinical practice must guide the physician in determining the best therapeutic options for patients with acute coronary syndromes. In the present narrative review, we discuss the latest novelties in the antiplatelet therapy of patients with acute coronary syndromes. We start with a description of platelet biology and the role of the main platelet signal pathways involved in platelet aggregation during an acute coronary syndrome. Then, we present the latest evidence on the evaluation of platelet function, focusing on the strengths and weaknesses of each platelet's function test. We continue our review by describing the role of aspirin and P2Y12 inhibitors in the treatment of acute coronary syndromes, critically appraising the available evidence from clinical trials, and providing current international guidelines and recommendations. Finally, we describe alternative therapeutic regimens to standard dual antiplatelet therapy, in particular for patients at high bleeding risk. The aim of our review is to give a comprehensive representation of current data on antiplatelet therapy in patients with acute coronary syndromes that could be useful both for clinicians and basic science researchers to be up-to-date on this complex topic.

Clinical Outcomes of Individualized Antiplatelet Therapy Based on Platelet Function Test in Patients After Percutaneous Coronary Intervention: A Systematic Review and Meta-analysis

ABSTRACT

Platelet function test (PFT) is universally used to assess platelet reactivity to antiplatelet drugs in patients after percutaneous coronary intervention (PCI). However, it remains controversial whether individualized antiplatelet therapy guided by PFT can improve the prognosis in patients after PCI. This meta-analysis was conducted to explore the efficacy and safety of individualized antiplatelet therapy guided by PFT in patients after PCI. Studies that compared PFT-guided antiplatelet therapy with standard antiplatelet therapy were researched. The risks of major adverse cardiovascular and cerebrovascular events (MACCE) and major bleeding events were assessed. Pooled odds ratios (ORs) with 95% CIs were obtained. Finally, a total of 16,835 patients from 22 studies met the criteria and were included in the meta-analysis. Compared with standard antiplatelet therapy, individualized antiplatelet therapy guided by PFT significantly decreased the risk of MACCE (OR: 0.58, 95% CI: 0.43-0.77) in patients after PCI. There was no significant difference in major bleeding events (OR: 0.85, 95% CI: 0.70-1.05, P = 0.13). This study identified that PFT-guided individualized antiplatelet therapy could reduce the incidence of MACCE without increasing the risk of hemorrhage in patients after PCI.

Efficacy and Safety of Ticagrelor and Clopidogrel in Patients with Stable Coronary Artery Disease Undergoing Percutaneous Coronary Intervention

AIM

The efficacy and safety of ticagrelor and clopidogrel in patients with stable coronary artery disease (SCAD) undergoing percutaneous coronary intervention (PCI) remain uncertain. Thus, this study aimed to compare the efficacy and safety of ticagrelor and clopidogrel in patients with SCAD treated with PCI.

METHODS

A total of 9,379 patients with SCAD undergoing PCI who received dual antiplatelet therapy (DAPT) were consecutively enrolled in two groups, namely, ticagrelor (n=1,081) and clopidogrel (n=8,298) groups. Major adverse cardiovascular and cerebrovascular events (MACCEs) and bleeding events according to ticagrelor or clopidogrel use were compared.

RESULTS

After propensity matching (n=1,081 in each group), ticagrelor was associated with fewer MACCEs compared with clopidogrel (3.6% vs. 5.7%, hazard ratio [HR]=0.62, 95% confidence interval [CI] 0.41-0.93, p=0.019), and the difference between ticagrelor and clopidogrel for bleeding events was nonsignificant (4.0% vs. 3.2%, HR=1.24, 95% CI 0.79-1.93, p=0.356). On the other hand, the difference between ticagrelor and clopidogrel for net adverse clinical events was significant (4.1% vs. 6.0%, HR=0.67, 95% CI 0.46-0.98, p=0.039). In a multivariate analysis, the use of ticagrelor, number of stents, previous history of diabetes, previous history of smoking, and ACC/AHA type B2 or C lesions were considered independent predictors of MACCEs, while radial artery access, previous history of stroke, and weight ＜60kg were independent predictors of bleeding events. Conclusions Ticagrelor was associated with a lower incidence of MACCEs without an increased risk of bleeding events in patients with SCAD receiving PCI.

Effects of Ticagrelor versus Clopidogrel in Patients with Coronary Bifurcation Lesions Undergoing Percutaneous Coronary Intervention

Background

Percutaneous treatment of coronary bifurcation lesions can potentially lead to higher risk of ischemic events than the nonbifurcation ones, thus calling for further optimization of dual antiplatelet therapy (DAPT). This study aimed to compare the clinical outcomes from ticagrelor and clopidogrel in bifurcation lesions patients undergoing percutaneous coronary intervention (PCI).

Methods

We performed a retrospective cohort study in patients with coronary bifurcation lesions. A total of 553 patients discharged on ticagrelor or clopidogrel combined with aspirin were recruited for 1-year follow-up. The incidences of primary endpoint (major adverse cardiovascular event [MACE]: a composite of cardiac death, myocardial infarction [MI] or stroke), secondary endpoints (the individual component of the primary endpoint or definite/probable stent thrombosis), and major bleeding (Bleeding Academic Research Consortium [BARC]≥3 bleeding events) were evaluated. To minimize the selection bias, a propensity score-matched population analysis was also conducted.

Results

The risks of both primary endpoint (8.15% and 12.01% for the ticagrelor and clopidogrel groups, respectively; adjusted hazards ratio [HR]: 0.488, 95% confidence interval [CI]: 0.277-0.861, P=0.013) and MI (4.44% and 8.48% for the ticagrelor and clopidogrel groups, respectively; adjusted HR: 0.341, 95% CI: 0.162-0.719, P=0.005) were significantly reduced in the ticagrelor group as compared with those of the clopidogrel counterpart, whereas the risk of major bleeding was comparable (2.96% and 2.47% for the ticagrelor and clopidogrel groups, respectively; adjusted HR: 0.972, 95% CI: 0.321-2.941, P=0.960). Propensity score-matched analysis confirmed such findings.

Conclusions

For patients with bifurcation lesions after PCI, ticagrelor treatment shows lower MACE and MI rates than the clopidogrel one, along with comparable major bleeding.

On-treatment platelet reactivity in the era of new ADP receptor blockers: data from a real-world clinical practice

Objectives: Several studies have questioned the need for platelet function testing in patients treated with new ADP receptor blockers (ADPRB). The aim of this study was to evaluate the prevalence of high on-treatment platelet reactivity (HTPR) among acute ST-elevation myocardial infarction (STEMI) patients treated with newer ADPRB.

Methods: A prospective study enrolling 44 acute previously ADPRB naive STEMI patients (31 men, 13 women) undergoing primary percutaneous coronary intervention (pPCI) was performed. Among the studied population 23 patients received prasugrel and 21 patients received ticagrelor. Antiplatelet response was tested with light transmission aggregometry (LTA) and vasodilator-stimulated phosphoprotein phosphorylation (VASP-P) flow cytometry assay. Samples were taken prior to coronary angiography (sample 1) and on the day after this procedure (sample 2).

Results: The mean platelet aggregation after induction with ADP was 51.7 ± 24.8% in sample 1 and 25.3 ± 20.1% in sample 2. An examination of VASP-P showed a mean platelet reactivity index of 56.8 ± 25.7% in sample 1 and 23.8 ± 23.1% in sample 2, respectively. The study identified 11.4% of patients in sample 2 as ADP receptor blocker non-responders. No significant differences were found between prasugrel-treated to ticagrelor-treated patients.

Conclusions: This pilot study demonstrated HTPR among acute STEMI patients treated with newer ADPRB.

Effect of tailored use of tirofiban in patients with Non-ST-elevation acute coronary syndrome undergoing percutaneous coronary intervention: a randomized controlled trial

Background

We conducted a randomized controlled trial to investigate whether an additional platelet inhibition with tirofiban would reduce the extent of myocardial damage and prevent periprocedural myonecrosis in patients with Non-ST-elevation acute coronary syndrome (NSTE-ACS) with a high residual platelet activity (HPR).

Methods

Patients with an HPR, defined as P₂Y₁₂ reaction unit (PRU) > 230, were randomly assigned to group A (tirofiban treatment, n = 30) or C1 (n = 30) and patients without an HPR to C2 (n = 78). Periprocedural myocardial damage was assessed using the area under the curve (AUC) of serial cardiac enzyme levels from the time of the procedure to post-36 h. Periprocedural myonecrosis incidence was evaluated.

Results

The troponin I AUC was not different between the groups (197.2 [41.5395.7], 37.9 [8.9313.9], 121.3 [43.7481.8] h∙ng/mL; p = 0.088). The results did not change when the baseline levels were adjusted (365.3 [279.5, 451.1], 293.0 [207.1, 379.0], and 298.0 [244.7, 351.3] h∙ng/mL; p = 0.487). The rate of periprocedural myonecrosis was also not different between the groups (53.0% vs. 50.0% vs. 33.3%, p = 0.092). The CK-MB isoenzyme analysis showed similar results. No difference in complications was noted.

Conclusion

Additional tirofiban administration was not beneficial to patients with NSTE-ACS even with an HPR.

Trial registration

Clinical trial no. NCT03114995, registered 11 April, 2017, retrospectively.

Electronic supplementary material

The online version of this article (10.1186/s12872-018-0938-6) contains supplementary material, which is available to authorized users.

Genome-wide and candidate gene approaches of clopidogrel efficacy using pharmacodynamic and clinical end points-Rationale and design of the International Clopidogrel Pharmacogenomics Consortium (ICPC)

RATIONALE

The P2Y12 receptor inhibitor clopidogrel is widely used in patients with acute coronary syndrome, percutaneous coronary intervention, or ischemic stroke. Platelet inhibition by clopidogrel shows wide interpatient variability, and high on-treatment platelet reactivity is a risk factor for atherothrombotic events, particularly in high-risk populations. CYP2C19 polymorphism plays an important role in this variability, but heritability estimates suggest that additional genetic variants remain unidentified. The aim of the International Clopidogrel Pharmacogenomics Consortium (ICPC) is to identify genetic determinants of clopidogrel pharmacodynamics and clinical response.

STUDY DESIGN

Based on the data published on www.clinicaltrials.gov, clopidogrel intervention studies containing genetic and platelet function data were identified for participation. Lead investigators were invited to share DNA samples, platelet function test results, patient characteristics, and cardiovascular outcomes to perform candidate gene and genome-wide studies.

RESULTS

In total, 17 study sites from 13 countries participate in the ICPC, contributing individual patient data from 8,829 patients. Available adenosine diphosphate-stimulated platelet function tests included vasodilator-stimulated phosphoprotein assay, light transmittance aggregometry, and the VerifyNow P2Y12 assay. A proof-of-principle analysis based on genotype data provided by each group showed a strong and consistent association between CYP2C19*2 and platelet reactivity (P value=5.1 × 10-40).

CONCLUSION

The ICPC aims to identify new loci influencing clopidogrel efficacy by using state-of-the-art genetic approaches in a large cohort of clopidogrel-treated patients to better understand the genetic basis of on-treatment response variability.

Impaired Platelet Aggregation and Rebalanced Hemostasis in Patients with Chronic Hepatitis C Virus Infection

Increased risk of both cardiovascular disease (CVD) and bleeding has been found in patients with chronic hepatitis C (CHC) infection, and a re-balanced hemostasis has been proposed. The aim of this study was to investigate functional whole blood coagulation and platelet function in CHC infection. The prospective study included 82 patients with CHC infection (39 with advanced liver fibrosis and 43 with no or mild liver fibrosis) and 39 healthy controls. A total of 33 patients were treated for CHC infection and achieved sustained virological response (SVR). Baseline and post-treatment blood samples were collected. Hemostasis was assessed by both standard coagulation tests and functional whole blood hemostatic assays (thromboelastograhy (TEG), and platelet aggregation (Multiplate). Patients with CHC and advanced fibrosis had impaired platelet aggregation both compared to patients with no or mild fibrosis and to healthy controls. Patients with CHC and advanced fibrosis also had lower antithrombin, platelet count, and coagulation factors II-VII-X compared to healthy controls. In contrast, TEG did not differ between groups. In treated patients achieving SVR, post-treatment platelet count was higher than pre-treatment counts (p = 0.033) and ADPtest, ASPItest, and RISTOhightest all increased post treatment (all p < 0.05). All Multiplate tests values, however, remained below those in the healthy controls. CHC-infected patients displayed evidence of rebalanced hemostasis with only partly hemostatic normalization in patients achieving SVR. The implications of rebalanced hemostasis and especially the impact on risk of CVD and bleeding warrants further studies.

Intensified Antiplatelet Treatment Reduces Major Cardiac Events in Patients with Clopidogrel Low Response: A Meta-analysis of Randomized Controlled Trials

BACKGROUND

Clopidogrel low response (CLR) is an independent risk factor of adverse outcomes in patients undergoing percutaneous coronary intervention (PCI), and intensified antiplatelet treatments (IAT) guided by platelet function assays might overcome laboratory CLR. However, whether IAT improves clinical outcomes is controversial.

METHODS

Relevant trials were identified in PubMed, the Cochrane Library, and the Chinese Medical Journal Network databases from their establishment to September 9, 2014. Trials were screened using predefined inclusion criteria. Conventional meta-analysis and cumulative meta-analysis were performed using the Review Manager 5.0 and STATA 12.0 software programs.

RESULTS

Thirteen randomized controlled trials involving 5111 patients with CLR were recruited. During a follow-up period of 1-12 months, the incidences of cardiovascular (CV) death, nonfatal myocardial infarction (MI), and stent thrombosis were significantly lower in the IAT arm than in the conventional antiplatelet treatment arm (relative risk [RR] = 0.45, 95% confidence interval [CI]: 0.36-0.57, P < 0.000,01), whereas bleeding was similar between the two arms (RR = 1.05, 95% CI: 0.86-1.27, P = 0.65).

CONCLUSIONS

IAT guided by platelet function assays reduces the risk of CV death, nonfatal MI, and stent thrombosis (ST) without an increased risk of bleeding in patients undergoing PCI and with CLR.

Type 2 Diabetes and ADP Receptor Blocker Therapy

Type 2 diabetes (T2D) is associated with several abnormalities in haemostasis predisposing to thrombosis. Moreover, T2D was recently connected with a failure in antiplatelet response to clopidogrel, the most commonly used ADP receptor blocker in clinical practice. Clopidogrel high on-treatment platelet reactivity (HTPR) was repeatedly associated with the risk of ischemic adverse events. Patients with T2D show significantly higher residual platelet reactivity on ADP receptor blocker therapy and are more frequently represented in the group of patients with HTPR. This paper reviews the current knowledge about possible interactions between T2D and ADP receptor blocker therapy.

Association of plasma miR-223 and platelet reactivity in patients with coronary artery disease on dual antiplatelet therapy: A preliminary report

Decreased plasma levels of microRNA-223 (miR-223), predominantly of platelet origin, were proposed as a surrogate marker of efficacy of antiplatelet therapy. However, higher on-treatment platelet reactivity was associated with lower plasma miR-223 in patients with coronary artery disease (CAD) on dual antiplatelet therapy (DAPT) including clopidogrel and aspirin. Our aim was to compare plasma miR-223 and platelet reactivity in CAD patients on DAPT with newer P2Y12 antagonists vs. clopidogrel. We studied 21 men with CAD admitted to our centre owing to a non-ST-elevation acute coronary syndrome, and with an uncomplicated hospital course. From the day of admission, the patients were receiving either clopidogrel (n = 11) or prasugrel/ticagrelor (n = 10) in addition to aspirin. Before discharge, miR-223 expression in plasma was estimated by quantitative polymerase chain reaction using the comparative Ct method relative to miR-16 as an endogenous control. Multiple electrode aggregometry was used to assess platelet aggregation in response to adenosine diphosphate (ADP). ADP-induced platelet reactivity was decreased in the patients treated with prasugrel or ticagrelor compared with those on clopidogrel (mean ± SD: 139 ± 71 vs. 313 ± 162 arbitrary units [AU]*min, p = 0.006), due to a more potent antiplatelet activity of the novel P2Y12 antagonists. Consequently, six out of seven patients in the lower tertile of the ADP-induced platelet aggregation were treated with the newer P2Y12 blockers, whereas six out of seven patients in the upper tertile were on clopidogrel. Plasma miR-223 was elevated with decreasing platelet reactivity (Spearman's rho = -0.52; p = 0.015 for trend), being significantly higher in the lower tertile of the ADP-induced platelet aggregation (median [range]: 1.06 [0.25-2.31]) vs. the upper tertile (0.20 [0.13-2.30]) (p = 0.04). In conclusion, our preliminary results argue against the notion of low plasma miR-223 as a marker of platelet responsiveness to DAPT. On the contrary, more potent platelet inhibition associated mainly with newer P2Y12 antagonists appears to coincide with higher miR-223 relative to the subjects with attenuated responsiveness to DAPT.