Acute thrombosis of everolimus-eluting platinum chromium stent caused by impaired prasugrel metabolism due to cytochrome P450 enzyme 2B6*2 (C64T) polymorphism: a case report

Advances and Perspectives in methods for identifying high platelet reactivity

Antiplatelet therapy is the foundational treatment for the prevention and treatment of coronary and cerebrovascular ischemic events in patients with coronary heart disease, ischemic stroke, and transient ischemic attack (TIA). However, with more and more studies reporting an increased risk of thrombosis in some patients due to poor response to therapeutic agents, the selection of appropriate P2Y12 inhibitors has become a major challenge that needs to be addressed urgently. Currently, commonly used oral P2Y12 inhibitors include clopidogrel, ticagrelor, and prasugrel. Assessing patients' risk factors before the development of treatment regimens by effectively predicting the risk of high platelet reactivity with specific P2Y12 inhibitors in advance to avert the occurrence of major adverse cardiovascular and cerebrovascular events (MACCE) is the key point to the problem. Up to now, methods available for predicting platelet reactivity include genetic testing, platelet function testing, and risk scores. This review provides a summarization of the existent available identification methods and analyzes the advantages and drawbacks of different methods in specific clinical settings, intending to guide the rational clinical application of P2Y12 receptor inhibitors.

A Japanese Dose of Prasugrel versus a Standard Dose of Clopidogrel in Patients with Acute Myocardial Infarction from the K-ACTIVE Registry

BACKGROUND

Dual antiplatelet therapy (DAPT) with aspirin plus P2Y12 inhibitor is used as a standard therapy for patients with acute myocardial infarction (AMI) treated with drug-eluting stents (DESs). In Japan, clopidogrel was the major P2Y12 inhibitor used for a decade until the new P2Y12 inhibitor, prasugrel, was introduced. Based on clinical studies considering Japanese features, the set dose for prasugrel was reduced to 20 mg as a loading dose (LD) and 3.75 mg as a maintenance dose (MD); these values are 60 and 10 mg, respectively, globally. Despite this dose discrepancy, little real-world clinical data regarding its efficacy and safety exist.

METHODS

From the K-ACTIVE registry, based on the DAPT regimen, patients were divided into a prasugrel group and a clopidogrel group. The ischemic event was a composite of cardiovascular death, non-fatal MI, and non-fatal stroke. The bleeding event was type 3 or 5 bleeding based on the Bleeding Academic Research Consortium (BARC) criteria.

RESULTS

Substantially more patients were prescribed prasugrel (n = 2786) than clopidogrel (n = 890). Clopidogrel tended to be selected over prasugrel in older patients with numerous comorbidities. Before adjustments were made, the cumulative incidence of ischemic events at 1 year was significantly greater in the clopidogrel group than in the prasugrel group (p = 0.007), while the cumulative incidence of bleeding events at 1 year was comparable between the groups (p = 0.131). After adjustments were made for the age, sex, body weight, creatine level, type of AMI, history of MI, approach site, oral anticoagulation therapy, presence of multivessel disease, Killip classification, and presence of intra-aortic balloon pumping, both ischemic and bleeding events became comparable between the groups.

CONCLUSION

A Japanese dose of prasugrel was commonly used in AMI patients in the real-world database. Both the prasugrel and clopidogrel groups showed comparable rates of 1 year ischemic and bleeding events.

Derivation of a Novel Scoring System Predicting High Platelet Reactivity on Prasugrel in Patients with Coronary Artery Disease

AIMS

High platelet reactivity (HPR) has been associated with an increased risk of thrombotic events in patients undergoing percutaneous coronary intervention. HPR has been well examined in patients treated with clopidogrel; however, HPR on prasugrel is poorly investigated.

METHODS

Four prospective studies were pooled, in which platelet reactivity on prasugrel was measured using VerifyNow assay; genotyping of CYP2C19 was also performed. Factors associated with HPR on prasugrel were identified using multivariable analysis to develop a risk prediction model.

RESULTS

In total, 180 patients were examined in this study, of whom 51 (28%) had HPR on prasugrel. The multivariable analysis indicated that hypertension, diabetes, hemodialysis, and the number of CYP2C19 loss-of-function (LOF) alleles are significant factors for HPR on prasugrel. These four factors were then incorporated to develop the HHD-GENE score. The receiver operating characteristic curve analysis showed that the HHD-GENE score predicted HPR on prasugrel (area under the curve (AUC) 0.74, best cutoff value 5, p＜0.001). With the best cutoff value, patients with the HHD-GENE score ≥ 5 had a significantly increased risk of HPR on prasugrel than their counterpart (50% vs. 18%, p＜0.001).

CONCLUSIONS

The HHD-GENE score consisting of hypertension, diabetes, hemodialysis, and CYP2C19 LOF alleles may be useful in identifying patients on prasugrel who are at high risk for HPR. External validation is needed to define the clinical utility of this novel scoring system.