Cost-effectiveness of Platelet Function-Guided Strategy with Clopidogrel or Ticagrelor

Assessing the efficacy of VerifyNow platelet-function testing in predicting postoperative thromboembolic complications of neuroendovascular surgery: A systematic review and meta-analysis (part 1)

BACKGROUND

Despite the heavily debated use of routine platelet-function testing, the VerifyNow Platelet Reactivity Unit (PRU) assay has been increasingly adopted as standard of care for assessing risk of postoperative thromboembolic complications of neuroendovascular surgery.

OBJECTIVE

We conducted a systematic review and meta-analysis to examine the relationship between platelet response and risk of ischemic events from neuroendovascular surgery, assess the efficacy of point-of-care platelet-function testing in predicting thromboembolic outcomes, and assess whether a clinically useful threshold for platelet response can be defined in order to standardize guidelines.

METHODS

PubMed, Embase, and Scopus were searched. Following deduplication, articles were first screened for relevance by title and abstract, followed by full text.

RESULTS

Of 735 resultant articles, 22 studies consisting of 3266 patients undergoing neuroendovascular intervention were included. Diagnoses included both intracranial and extracranial pathologies, of which 45.8% were treated with flow diversion, 16.4% with stent-assisted coil embolization, 15.8% with intracranial stenting, 12.0% with simple coil embolization, 3.4% with balloon-assisted coil embolization, 3.6% with extracranial stenting, and 3.0% with an alternate method. 54.5% (12/22) of studies determined platelet hyporesponse to be an independent predictor of postoperative thromboembolic complications, with 27.3% (6/22) of studies reporting a similar, but non-statistically significant trend. 18.2% (4/22) of studies found no relationship between platelet response and postoperative thromboembolic complications. The estimated clinical threshold for PRU to prevent thromboembolic complications varied greatly across studies (Range: > 144-295 PRU). Meta-analysis found platelet hyporesponse to have a 2.23-fold increased risk of thromboembolic complications compared to normoresponders (RR = 2.23, P = 0.03).

CONCLUSION

While PRU demonstrates a significant predictive value for postoperative thromboembolic complications of neuroendovascular surgery, the target therapeutic threshold for minimizing ischemic events remains unclear. Further studies, such as large multicenter cohorts of the existing data, are needed to standardize guidelines.

Population pharmacokinetic-pharmacodynamic modeling of clopidogrel for dose regimen optimization based on CYP2C19 phenotypes: A proof of concept study

Clopidogrel is an antiplatelet drug used to reduce the risk of acute coronary syndrome and stroke. It is converted by CYP2C19 to its active metabolite; therefore, poor metabolizers (PMs) of CYP2C19 exhibit diminished antiplatelet effects. Herein, we conducted a proof-of-concept study for using population pharmacokinetic-pharmacodynamic (PK-PD) modeling to recommend a personalized clopidogrel dosing regimen for individuals with varying CYP2C19 phenotypes and baseline P2Y12 reaction unit (PRU) levels. Data from a prospective phase I clinical trial involving 36 healthy male participants were used to develop the population PK-PD model predicting the concentrations of clopidogrel, clopidogrel H4, and clopidogrel carboxylic acid, and linking clopidogrel H4 concentrations to changes in PRU levels. A two-compartment model effectively described the PKs of both clopidogrel and clopidogrel carboxylic acid, and a one-compartment model of those of clopidogrel H4. The CYP2C19 phenotype was identified as a significant covariate influencing the metabolic conversion of the parent drug to its metabolites. A PD submodel of clopidogrel H4 that stimulated the fractional turnover rate of PRU levels showed the best performance. Monte Carlo simulations suggested that PMs require three to four times higher doses than extensive metabolizers to reach the target PRU level. Individuals within the top 20th percentile of baseline PRU levels were shown to require 2.5-3 times higher doses than those in the bottom 20th percentile. We successfully developed a population PK-PD model for clopidogrel considering the impact of CYP2C19 phenotypes and baseline PRU levels. Further studies are necessary to confirm actual dosing recommendations for clopidogrel.

Safety and efficacy of tailored antiplatelet therapy using prasugrel or ticagrelor based on clopidogrel responsiveness in endovascular treatment for intracranial aneurysms: a meta-analysis

BACKGROUND

Clopidogrel (CPG)-based dual antiplatelet therapy (DAPT) in combination with aspirin has been widely used before endovascular procedures for intracranial aneurysms to prevent procedural thromboembolic complication (TEC). However, the main drawback of CPG is the high proportion of hyporesponders. This study sought to investigate the usefulness of tailored DAPT using novel P2Y12 inhibitors (prasugrel or ticagrelor, (PSG/TCG)) guided by a platelet reactivity test (PRT), compared with CPG-based conventional DAPT.

METHOD

Data were extracted from PubMed, Embase, and Cochrane Central Register of Controlled Trials by two independent reviewers. A random effects model was used to investigate the procedural TEC and hemorrhagic complications (HEC) of the tailored DAPT and conventional therapy by risk ratios (RR) and 95% confidence intervals (95% CI). Additionally, we performed subgroup analyses to directly compare prasugrel/ticagrelor with CPG.

RESULTS

Six studies comprising 2557 patients were included in the analysis. Compared with conventional non-tailored therapy, PRT-guided tailored DAPT with PSG/TCG was associated with a lower risk of TEC (RR 0.40, 95% CI 0.22 to 0.74, P=0.004) without increasing HEC rates. The subgroup analysis showed that the switch to PSG/TCG in CPG hyporesponders was related to a lower incidence of TEC (RR 0.46, 95% CI 0.23 to 0.95, P=0.03) without a difference in HEC, compared with maintenance of CPG in CPG responders.

CONCLUSION

Evidence from this analysis supports PRT-guided tailored DAPT (using PSG/TCG) as a better choice for preparation towards endovascular procedures to treat aneurysms. Furthermore, it suggests that PSG/TCG is not limited to the role of a substitute for CPG but may be a first-line agent for DAPT.

Exploring the potential cost-effectiveness of a novel platelet assay for guiding dual antiplatelet therapy duration in acute coronary syndrome patients following percutaneous coronary intervention

OBJECTIVE

Duration of dual antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI) influences ischemic and bleeding events. Platelet expression of constant fragment of immunoglobulin, low affinity IIa, receptor (FcγRIIa) independently predicts risk of ischemic complications and is proposed as a tool to guide individualized care.

METHODS

We used a Markov model to predict lifetime ischemic and bleeding events and healthcare costs in acute myocardial infarction (MI) patients treated with PCI and DAPT and to project cost-effectiveness of platelet FcγRIIa-assay-guided care (30:3 months DAPT for patients at high: low ischemic risk) versus current standard care (12 months DAPT) from the perspective of the US healthcare system. Model inputs included assay sensitivity and specificity, ischemic and bleeding event rates, and impacts on quality of life, mortality, and costs. Assay cost was $90. Sensitivity analyses were conducted over a range of plausible clinical and cost assumptions.

RESULTS

Under base case assumptions, platelet FcγRIIa-assay-guided DAPT duration was projected to increase lifetime costs by $19 versus standard care, with an associated incremental cost-effectiveness ratio (ICER) of $436 per quality-adjusted life-year (QALY) gained. Assay-guided DAPT duration was consistent with high-value care (ICER < $50 000/QALY gained) over a broad range of alternative assumptions.

CONCLUSION

Based on a decision-analytic model, for patients with MI treated with PCI, the additional costs of the platelet FcγRIIa assay for guiding DAPT duration would be largely offset by reductions in downstream event-related costs, and assay-guided care would be highly cost-effective by current standards. These findings require confirmation in prospective studies and in a randomized clinical trial of assay-guided versus nonassay-guided DAPT duration.

Modified ticagrelor loading doses according to the vasodilator-stimulated phosphoprotein phosphorylation index improve the clinical outcome in ST-elevation myocardial infarction patients with high on-treatment platelet reactivity

BACKGROUND

Current guidelines recommend a standard ticagrelor loading dose (LD) in ST-segment elevation myocardial infarction (STEMI) patients. However, antiplatelet therapy in STEMI patients at high risk of thrombotic events is suboptimal. The study was conducted to validate whether vasodilatorstimulated phosphoprotein (VASP)-guided ticagrelor dosing individual therapy may result in more effective platelet inhibition and better clinical outcomes.

METHODS

This trial included 374 STEMI patients with a low platelet response after ticagrelor LD. The patients were randomized into a control group and a VASP-guided group, where the ticagrelor pretreatment was individually adjusted before and after percutaneous coronary intervention (PCI) to obtain a VASP index < 50%. Up to 2 additional boluses of ticagrelor (every additional dosing was 90 mg) were prescribed after the first LD, and the VASP index was assessed 2 hours after each administration until a VASP index < 50% was obtained or up to 3 dosages (360 mg). The primary endpoint was major adverse cardiovascular events (MACEs) at 30 days. The secondary endpoints were thrombolysis in myocardial infarction (TIMI) major and minor bleeding.

RESULTS

The characteristics were similar in the two groups. After the ticagrelor doses increased, the platelet reactivity index (PRI) decreased, and 98.4% of patients reached PRI < 50% in the VASP-guided group. The adenosine concentration increased, and the rate of MACE was significantly lower in the VASP-guided group (10 [5.3%] vs. 20 [10.8%], hazard ratio 2.38, 95% confidence interval 1.21-3.28, p = 0.007). There were no major hemorrhagic complications (0 vs. 0, p = 1.0). The rate of minor bleeding in the VASP-guided group was higher than that in the control group, but the difference was not significant (24 [12.8%] vs. 16 [8.6%], p = 0.068).

CONCLUSIONS

The incremental ticagrelor dosing strategy decreases the rate of MACE after PCI without increasing major and minor bleeding.

Perioperative management of antiplatelet therapy in noncardiac surgery

PURPOSE OF REVIEW

Perioperative management of antiplatelet agents (APAs) in the setting of noncardiac surgery is a controversial topic of balancing bleeding versus thrombotic risks.

RECENT FINDINGS

Recent data do not support a clear association between continuation or discontinuation of APAs and rates of ischemic events, bleeding complications, and mortality up to 6 months after surgery. Clinical factors, such as indication and urgency of the operation, time since stent placement, invasiveness of the procedure, preoperative cardiac optimization, underlying functional status, as well as perioperative control of supply-demand mismatch and bleeding may be more responsible for adverse outcome than antiplatelet management.

SUMMARY

Perioperative management of antiplatelet therapy (APT) should be individually tailored based on consensus among the anesthesiologist, cardiologist, surgeon, and patient to minimize both ischemic/thrombotic and bleeding risks. Where possible, surgery should be delayed for a minimum of 1 month but ideally for 3-6 months from the index cardiac event. If bleeding risk is acceptable, dual APT (DAPT) should be continued perioperatively; otherwise P2Y12 inhibitor therapy should be discontinued for the minimum amount of time possible and aspirin monotherapy continued. If bleeding risk is prohibitive, both aspirin and P2Y12 inhibitor therapy should be interrupted and bridging therapy may be considered in patients with high thrombotic risk.