Universal versus platelet reactivity assay-driven use of P2Y12 inhibitors in acute coronary syndrome patients

CYP2C19 LOF and GOF-Guided Antiplatelet Therapy in Patients with Acute Coronary Syndrome: A Cost-Effectiveness Analysis

PURPOSE

This study aimed to examine the cost-effectiveness of CYP2C19 loss-of-function and gain-of-function allele guided (LOF/GOF-guided) antiplatelet therapy in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI).

METHODS

A life-long decision-analytic model was designed to simulate outcomes of three strategies: universal clopidogrel (75 mg daily), universal alternative P2Y₁₂ inhibitor (prasugrel 10 mg daily or ticagrelor 90 mg twice daily), and LOF/GOF-guided therapy (LOF/GOF allele carriers receiving alternative P2Y₁₂ inhibitor, wild-type patients receiving clopidogrel). Model outcomes included clinical event rates, quality-adjusted life-years (QALYs) gained and direct medical costs from perspective of US healthcare provider.

RESULTS

Base-case analysis found nonfatal myocardial infarction (5.62%) and stent thrombosis (1.2%) to be the lowest in universal alternative P2Y₁₂ inhibitor arm, whereas nonfatal stroke (0.72%), cardiovascular death (2.42%), and major bleeding (2.73%) were lowest in LOF/GOF-guided group. LOF/GOF-guided arm gained the highest QALYs (7.5301 QALYs) at lowest life-long cost (USD 76,450). One-way sensitivity analysis showed base-case results were subject to the hazard ratio of cardiovascular death in carriers versus non-carriers of LOF allele and hazard ratio of cardiovascular death in non-carriers of LOF allele versus general patients. In probabilistic sensitivity analysis of 10,000 Monte Carlo simulations, LOF/GOF-guided therapy, universal alternative P2Y₁₂ inhibitor, and universal clopidogrel were the preferred strategy (willingness-to-pay threshold = 50,000 USD/QALY) in 99.07%, 0.04%, and 0.89% of time, respectively.

CONCLUSIONS

Using both CYP2C19 GOF and LOF alleles to select antiplatelet therapy appears to be the preferred antiplatelet strategy over universal clopidogrel and universal alternative P2Y₁₂ inhibitor therapy for ACS patients with PCI.

Platelet function testing as a biomarker for efficacy of antiplatelet drugs

Despite the overwhelming evidence in support of the efficacy of dual antiplatelet therapy with aspirin and clopidogrel, it is also obvious that not all patients benefit from these drugs to the same extent. This interindividual variability in platelet responses may underlie clinical differences in drug efficacy, with potential for optimization of antiplatelet therapy to prevent ischemic events without excessively increasing bleeding risk. This review presents the current evidence regarding platelet function testing for monitoring of antiplatelet therapy, with emphasis on the prognostic value of platelet function testing to predict ischemic and bleeding events. The potential of platelet function testing to provide personalized antiplatelet therapy is also discussed, with an outlook toward the future of platelet function testing in high-risk individuals.

Cost–effectiveness analysis of personalized antiplatelet therapy in patients with acute coronary syndrome

Aim: This study aimed to compare the clinical and economic outcomes of pharmacogenetic-guided (PG-guided) and platelet reactivity testing-guided antiplatelet therapy for patients with acute coronary syndrome undergoing percutaneous coronary intervention. Methods: A decision-analytic model was simulated including four antiplatelet strategies: universal clopidogrel 75 mg daily, universal alternative P2Y12 inhibitor (prasugrel or ticagrelor), PG-guided therapy, and platelet reactivity testing-guided therapy. Results: PG-guided therapy was the preferred option with lowest cost (US$75,208) and highest quality-adjusted life years gained (7.6249 quality-adjusted life years). The base-case results were robust in sensitivity analysis. Conclusion: PG-guided antiplatelet therapy showed the highest probability to be preferred antiplatelet strategy for acute coronary syndrome patients with percutaneous coronary intervention.

Vascular risk levels affect the predictive value of platelet reactivity for the occurrence of MACE in patients on clopidogrel. Systematic review and meta-analysis of individual patient data

Prior studies have shown an association between high on-clopidogrel platelet reactivity (PR) and the risk of major adverse cardiovascular events (MACE). However, large intervention trials on PR-tailored treatments have been neutral. The role and usefulness of PR with regard to levels of cardiovascular risk are unclear. We undertook a systematic review and meta-analysis of individual patient data on MACE outcomes (acute coronary syndromes (ACS), ischaemic strokes, and vascular deaths) in relation to PR and its interaction with cardiovascular risk levels. PR was determined using ADP-induced light transmission aggregometry with a primary concentration of 20 µM ADP. Thirteen prospective studies totaled 6,478 clopidogrel-treated patients who experienced 421 MACE (6.5 %) during a median follow-up of 12 months. The strength of the association between the risk of MACE and PR increased significantly (p=0.04) with the number of risk factors present (age> 75 years, ACS at inclusion, diabetes, and hypertension). No association was detected in patients with no risk factor (p=0.48). In patients presenting one risk factor, only high-PR was associated with an increased risk of MACE (HR 3.2, p=0.001). In patients presenting ≥ 2 risk factors, the increase of risk started from medium-PR (medium-PR: HR=2.9, p=0.0004; high-PR: HR=3.7, p=0.0003). PR allowed the reclassification of 44 % of the total population to a different risk level for the outcome of MACE, mostly in intermediate or high risk patients. In conclusion, the magnitude of the association between PR and MACE risk is strongly dependent on the level of cardiovascular risk faced by patients on clopidogrel.

Initial experience with ticagrelor in patients with critical limb ischemia and high on-clopidogrel platelet reactivity undergoing complex peripheral endovascular procedures

PURPOSE

To investigate the safety and efficacy of ticagrelor in patients with critical limb ischemia (CLI) and high on-clopidogrel platelet reactivity (HCPR) undergoing complex, limb-salvage, peripheral endovascular procedures (PEP).

MATERIALS AND METHODS

The study included consecutive patients with HCPR undergoing PEP for CLI. HCPR was defined as platelet reaction units (PRU) >234 as assessed by the VerifyNow P2Y12 assay. Patients with HCPR were prescribed ticagrelor, 180/90 mg twice daily, and aspirin, 100 mg daily, for 6 months and ticagrelor, 180/90 mg twice daily, thereafter. Primary safety outcome was total major bleeding, and primary efficacy outcome was the composite of cardiovascular death and major amputation. Secondary outcomes included the level of platelet inhibition achieved and target limb revascularization (TLR)-free survival rate.

RESULTS

In total, 37 CLI patients with 40 limbs were investigated. Mean follow-up period was 11.3 ± 5.0 months (range 6-21). The mean treated lesion length was 229.2 ± 71.4 mm in the femoropopliteal axis and 179.3 ± 83.9 mm in the infrapopliteal arteries. No major or minor bleeding was detected. There were four periprocedural minor adverse events (10.8%), and in two cases (5.6%) ticagrelor was discontinued. In all patients, ticagrelor achieved platelet inhibition lower than the cut-off value. Mean PRU during clopidogrel therapy was 308.4 ± 41.8 (range 257-422) versus 67.0 ± 52.8 (range 2-189) when switched to ticagrelor; p < 0.0001. Kaplan-Meier estimated primary efficacy outcome and TLR-free survival rates were 92.0 and 67.3% at 12 months, respectively.

CONCLUSION

In this series of CLI patients with HCPR undergoing complex PEP, initial experience with ticagrelor was proven safe and efficient because it resulted in sufficient platelet inhibition and satisfactory clinical results without major complications.