ACCF/AHA Clopidogrel clinical alert: approaches to the FDA "boxed warning": a report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents and the American Heart Association

Outcomes of Ticagrelor Versus High-dose Clopidogrel in CYP2C19 Intermediate Metabolizer Undergoing Percutaneous Coronary Intervention for Acute Coronary Syndromes

ABSTRACT

Guidelines on antiplatelet recommendation for CYP2C19 intermediate metabolizer (IM) have not come to an agreement. This study aimed to evaluate the clinical benefit of ticagrelor when compared with high-dose clopidogrel in CYP2C19 IM after percutaneous coronary intervention for acute coronary syndromes. Patients were enrolled according to CYP2C19 genotype and individual antiplatelet therapy. Patient characteristics and clinical outcomes were collected through electronic medical record system. The primary outcome was major adverse cardiac and cerebrovascular event (MACCE), namely a composite of death from cardiovascular causes, myocardial infarction, stroke, and stent thrombosis within 12 months. The secondary outcome was Bleeding Academic Research Consortium scale bleeding events within 12 months. The Cox proportional hazards regression model was performed, with inverse probability treatment weighting (IPTW) adjusting for potential confounders. A total of 532 CYP2C19 IM were enrolled in this retrospective single-center study. No statistically significant difference in incidence rate of MACCE was found between patients receiving ticagrelor versus clopidogrel (7.01 vs. 9.52 per 100 patient-years; IPTW-adjusted hazard ratio 0.71; 95% confidence interval: 0.32-1.58; adjusted log-rank P = 0.396), but the incidence rate of Bleeding Academic Research Consortium type 2, 3, or 5 bleeding events was statistically higher in the loss of function-ticagrelor group than in the loss of function-clopidogrel group (13.53 vs. 6.16 per 100 patient-years; IPTW-adjusted hazard ratio: 2.29; 95% confidence interval: 1.10-4.78; adjusted log-rank P = 0.027). Ticagrelor treatment in CYP2C19 IM resulted in a statistically higher risk of bleeding compared with high-dose clopidogrel, whereas a clear association between treatments and MACCE warrants further investigations.

Role of Cyp2c19 Genotype-Guided Antiplatelet Therapy After Percutaneous Coronary Intervention

PURPOSE OF REVIEW

Identification of a reliable discriminatory test to accurately stratify patient responses to antiplatelet therapy following coronary revascularization has become increasingly desirable to optimize therapeutic efficacy and safety.

RECENT FINDINGS

The expansion of platelet function testing to include genotype assessment has been an evolutionary journey, initially fraught with confounding results. However, more recent and rigorous data analysis suggests that genotype testing- guided, tailored antiplatelet therapy may hold promise in optimizing treatment of patients after coronary intervention. Current evidence increasingly supports the use of genotype guided CYP2C19 testing to better match the post coronary intervention patient with the most efficacious and least risky antiplatelet inhibitor. The risk stratification of poor, intermediate, and good metabolizers of these drugs with such testing promises to yield clinical dividends in terms of morbidity, mortality and cost control, in this growing patient population.

QPGx-CARES: Qatar pharmacogenetics clinical applications and research enhancement strategies

Pharmacogenetic (PGx)-informed medication prescription is a cutting-edge genomic application in contemporary medicine, offering the potential to overcome the conventional "trial-and-error" approach in drug prescription. The ability to use an individual's genetic profile to predict drug responses allows for personalized drug and dosage selection, thereby enhancing the safety and efficacy of treatments. However, despite significant scientific and clinical advancements in PGx, its integration into routine healthcare practices remains limited. To address this gap, the Qatar Genome Program (QGP) has embarked on an ambitious initiative known as QPGx-CARES (Qatar Pharmacogenetics Clinical Applications and Research Enhancement Strategies), which aims to set a roadmap for optimizing PGx research and clinical implementation on a national scale. The goal of QPGx-CARES initiative is to integrate PGx testing into clinical settings with the aim of improving patient health outcomes. In 2022, QGP initiated several implementation projects in various clinical settings. These projects aimed to evaluate the clinical utility of PGx testing, gather valuable insights into the effective dissemination of PGx data to healthcare professionals and patients, and identify the gaps and the challenges for wider adoption. QPGx-CARES strategy aimed to integrate evidence-based PGx findings into clinical practice, focusing on implementing PGx testing for cardiovascular medications, supported by robust scientific evidence. The current initiative sets a precedent for the nationwide implementation of precision medicine across diverse clinical domains.

Implementation of CYP2C19 genotyping and clinical outcomes following percutaneous coronary intervention in East Asian patients treated with oral P2Y12 inhibitors

BACKGROUND

The CYP2C19 loss-of-function variants have significant impact on response to clopidogrel. The efficacy and safety of tailored antiplatelet therapy under the guidance of CYP2C19 genetic polymorphisms remains elusive for patients undergoing percutaneous coronary intervention (PCI).

OBJECTIVES

The aims of the present study were to investigate the impact of clinical implementation of CYP2C19 genotyping on the selection of oral P2Y12 inhibitor therapy following PCI, and to estimate the risk of adverse outcomes for patients with different genotype status treated with alternative or traditional P2Y12 inhibitor.

METHODS

Data from a single-center registry enrolling 41,090 consecutive PCI patients treated with dual antiplatelet therapy after PCI were analyzed. Risk of major adverse cardiovascular events (MACEs) and bleeding events within 12 months after PCI were compared across CYP2C19 genotype and antiplatelet therapy groups using Cox proportional hazards models.

RESULTS

CYP2C19 genotyping was successfully achieved for 9081 patients, of whom baseline characteristics significantly differed from non-genotyped patients. A higher proportion of genotyped patients were prescribed ticagrelor compared with non-genotyped patients (27.0 % vs. 15.5 %, P < 0.001). CYP2C19 metabolic status was an independent predictor for use of ticagrelor (P < 0.001). Ticagrelor was significantly associated with a lower risk of MACEs in poor metabolizers (adjusted hazard ratio 0.62, 95 % confidence interval 0.42 to 0.92, P = 0.017), but not in intermediate metabolizers or normal metabolizers. The interaction was not statistically significant (P for interaction = 0.252).

CONCLUSIONS

Genotype information on CYP2C19 metabolic status was associated with an increase in the use of potent antiplatelet therapy in PCI patients. Patients prescribed with clopidogrel has a higher risk of MACEs among poor metabolizers, which suggested the potential application of genotype-guided P2Y12 inhibitor selection for improving clinical outcomes.

Impact of Ticagrelor Versus Clopidogrel on Bleeding Outcomes of Isolated Coronary Artery Bypass Grafting

BACKGROUND

Increased bleeding risks have been documented in patients exposed to P2Y₁₂ inhibitors within 5 days of coronary artery bypass surgery (CABG). This study aimed to determine the relative CABG bleeding risks of clopidogrel versus ticagrelor exposure and the proper time course of ticagrelor discontinuation prior to surgery.

METHODS

Clinical outcomes were assessed in 2075 isolated CABG patients, including 375 who had received P2Y₁₂ inhibitors within 5 days of surgery (155 clopidogrel, 213 ticagrelor, 7 prasugrel). BARC-4 CABG bleeding complications and perioperative blood product usage were assessed in propensity-matched P2Y₁₂-inhibited and non-P2Y₁₂-inhibited cohorts.

RESULTS

P2Y₁₂-inhibited patients (n = 375) in comparison to matched non-P2Y₁₂-inhibited patients (n = 1138) had higher rates of re-operation for bleeding (3.8 % vs 1.3 %, p = 0.003), postoperative red blood cell transfusion ≥5 units (5.7 % vs 2.7 %, p = 0.007), and intraoperative and postoperative blood product utilization (42.3 % vs 27.1 %, p < 0.001; 41.8 % vs 32.2 %, p < 0.001, respectively). Univariate predictors of BARC-4 bleeding included clopidogrel (OR: 2.145, 95 % CI: 1.131-4.067, p = 0.019) and ticagrelor discontinued within 3 days of surgery (OR: 2.153, 95 % CI: 1.003-4.169, p = 0.049). Multivariate logistic regression demonstrated that only clopidogrel exposure was an independent BARC-4 bleeding predictor (OR: 1.850, 95 % CI: 1.007-3.398, p = 0.048). Unadjusted ticagrelor patients with drug discontinuation 4-5 days prior to CABG only demonstrated higher rates of perioperative platelet transfusion, without additional signs of excessive bleeding.

CONCLUSIONS

Clopidogrel exposure within 5 days of CABG is an independent predictor of BARC-4 bleeding, whereas major ticagrelor bleeding effects are confined to drug exposure within 3 days of surgery.

Genotyping genetic variants of CYP2C19 for precision antiplatelet dosing: state of the art and future perspectives

INTRODUCTION

Clopidogrel is the only antiplatelet agent whose activity is significantly affected by CYP2C19 polymorphism.

AREAS COVERED

This review has summarized the available evidence on the clinically significant association between CYP2C19 polymorphism and clopidogrel-based therapy; reviewed the current recommendations for clinical use of CYP2C19 genotype test results in patients on clopidogrel treatment; and discussed possible pitfalls of routine application, and future perspectives of antiplatelets pharmacogenetics.

EXPERT OPINION

The available body of evidence, reflected in several meta-analyses and high-quality clinical practice guidelines, shows that the presence of CYP2C19 LOF alleles, especially CYP2C19*2, correlates with impaired activation of clopidogrel and variable platelet inhibition, followed by minimal or no antiplatelet effect, and higher risk of treatment failure. In combination with other known risk factors, CYP2C19 genetic testing could be very valuable in predicting low clopidogrel efficacy. At the same time, it could be very successful in selecting patients who will most probably benefit from the clopidogrel-based therapy, thus decreasing the pool of those who might need more expensive and otherwise riskier antiplatelet alternatives.

P2Y12 reaction units and ischemic and bleeding events after neuro-endovascular treatment

BACKGROUND AND PURPOSE

To investigate the associations of perioperative P2Y12 reaction units (PRU) measured using VerifyNow with ischemic and bleeding events, and to determine the PRU threshold in the setting of elective neuro-endovascular treatment (EVT) for intracranial/extracranial vascular disease in patients taking aspirin and clopidogrel.

METHODS

Of the patients undergoing elective neuro-EVT while taking aspirin and clopidogrel, those taking both antiplatelet agents for 7 days or more and whose PRU and aspirin reaction units (ARU) were measured were included. The primary and safety outcomes were defined as symptomatic ischemic and major bleeding events within 30 days after EVT.

RESULTS

A total of 197 patients were available for the analyses. Higher PRU was associated with symptomatic ischemic events on multivariable logistic analysis (odds ratio per 10 increase 1.14 [95% confidence interval 1.03-1.27], p=0.011). Receiver operating characteristic curve analysis showed that PRU ≥212 was the threshold to predict symptomatic ischemic events (area under the curve=0.73; sensitivity, 62.5%; specificity, 82.0%). Lower PRU was also associated with major bleeding events (odds ratio per 10 increase 0.87 [0.78-0.96], p=0.004), and the threshold to predict major bleeding events was PRU ≤46 (area under the curve=0.76; sensitivity, 70.0%; specificity, 87.2%) CONCLUSIONS: The PRU value was associated with symptomatic ischemic and major bleeding events after elective neuro-EVT in patients taking aspirin and clopidogrel. PRU ≥212 and PRU ≤46 appeared to be the threshold values to predict symptomatic ischemic and major bleeding events, respectively.

Clinical non-effectiveness of clopidogrel use for peripheral artery disease in patients with CYP2C19 polymorphisms: a systematic review

PURPOSE

To conduct a systematic review to identify studies that assessed the association between CYP2C19 polymorphisms and clinical outcomes in peripheral artery disease (PAD) patients who took clopidogrel.

METHODS

We systematically searched Ovid EMBASE, PubMed, and Web of Science from November 1997 (inception) to September 2020. We included observational studies evaluating how CYP2C19 polymorphism is associated with clopidogrel's effectiveness and safety among patients with PAD. We extracted relevant information details from eligible studies (e.g., study type, patient population, study outcomes). We used the Risk of Bias in Non-randomized Studies-of Interventions (ROBINS-I) Tool to assess the risk of bias for included observational studies.

RESULTS

The outcomes of interest were the effectiveness and safety of clopidogrel. The effectiveness outcomes included clinical ineffectiveness (e.g., restenosis). The safety outcomes included bleeding and death related to the use of clopidogrel. We identified four observational studies with a sample size ranging from 50 to 278. Outcomes and comparison groups of the studies varied. Three studies (75%) had an overall low risk of bias. All included studies demonstrated that carrying CYP2C19 loss of function (LOF) alleles was significantly associated with reduced clinical effectiveness and safety of clopidogrel.

CONCLUSIONS

Our systematic review showed an association between CYP2C19 LOF alleles and reduced functions of clopidogrel. The use of CYP2C19 testing in PAD patients prescribed clopidogrel may help improve the clinical outcomes. However, based on the limited evidence, there is a need for randomized clinical trials in PAD patients to test both the effectiveness and safety outcomes of clopidogrel.

Applying Pharmacogenomic Guidelines to Combat Medical Care

Pharmacogenomics is a pillar of personalized medicine that has the potential to deliver optimized treatment in many medical settings. Military medicine in the deployed setting is unique and therefore warrants separate assessment pertaining to its potential capabilities and impact. Pharmacogenomics for United States Active Duty Service Members medical care in the deployed setting has not, to our knowledge, been previously reviewed. We present potential applications of pharmacogenomics to forward medical care through two comprehensive references for deployed medical care, the Tactical Combat Casualty Care Guidelines (TCCC) and Emergency War Surgery (EWS) fifth edition. All drugs within the deployment manuals, TCCC guidelines and EWS book, were identified and the list was cross-referenced to the Clinical Pharmacogenetics Implementation Consortium guidelines and genes-drugs interactions list as well as the Food and Drug Administration Table of Pharmacogenomics Biomarkers in Drug Labeling. Ten pharmacologic categories were identified, consisting of 15 drugs, along with the classes, aminogylcosides, beta-blockers, and volatile anesthetics. Drugs and pharmacogenomics liabilities were tabulated. Eight specific drugs or classes are expounded upon given the belief of the authors of their potential for impacting future treatment on the battlefield in the setting of prolonged field care. This review outlines several genes with liabilities in the prolonged field care setting and areas that may produce improved care with further study.

Genotype-Guided P2Y 12 Inhibitor Therapy After Percutaneous Coronary Intervention: A Bayesian Analysis

Background:

Among patients receiving percutaneous coronary intervention (PCI), the role of a genotype-guided approach for antiplatelet therapy compared with usual care is unclear. We conducted a Bayesian analysis of the entire TAILOR-PCI (Tailored Antiplatelet Initiation to Lessen Outcomes Due to Decreased Clopidogrel Response After Percutaneous Coronary Intervention) randomized clinical trial population to evaluate the effect of the genotype-guided antiplatelet therapy post-PCI compared with the usual care on the risk of major adverse cardiovascular events (MACE).

Methods:

The primary outcome for our study was the composite of MACE (myocardial infarction, stroke, and cardiovascular death). Secondary outcomes included cardiovascular death, stroke, myocardial infarction, stent thrombosis, and major/minor bleeding. Bayesian modeling was used to estimate the probability of clinical benefit of genotype-guided therapy using (1) noninformative priors (ie, analyzing the TAILOR-PCI trial) and (2) informative priors derived from the ADAPT, POPular Genetics, IAC-PCI, and PHARMCLO trials (ie, analyzing TAILOR-PCI trial in the context of prior evidence). Risk ratio (RR: ratio of cumulative outcome incidence between genotype-guided and conventional therapy group) and 95% credible interval (CrI) were estimated for the study outcomes, and probability estimates for RR <1 were computed.

Results:

Using noninformative priors, in TAILOR-PCI the RR for MACE was 0.78 (95% CrI, 0.55–1.07) in genotype-guided therapy after PCI, and the probability of RR <1 was 94%. Using noninformative priors, the probability of RR <1 for cardiovascular death (RR, 0.95 [95% CrI, 0.52–1.74]), stroke (RR, 0.68 [95% CrI, 0.44–1.06]), myocardial infarction (RR, 0.84 [95% CrI, 0.37–1.89]), stent thrombosis (RR, 0.75 [95% CrI, 0.37–1.45]), and major or minor bleeding (RR, 1.22 [95% CrI, 0.84–1.77]) were 57%, 96%, 67%, 81%, and 15%, respectively. Using informative priors, the posterior probability of RR <1 for MACE, from genotype-guided therapy, was 99% (RR, 0.69 [95% CrI, 0.57–0.84]). Using informative priors, the posterior probability of RR <1 for cardiovascular death (RR, 0.86 [95% CrI, 0.61–1.19]), stroke (RR, 0.69 [95% CrI, 0.48–0.99]), myocardial infarction (RR:0.56 [95% CrI, 0.40–0.78]), stent thrombosis (RR, 0.59 [95% CrI, 0.38–0.94]), and major or minor bleeding (RR, 0.84 [95% CrI, 0.70–0.99]) were 81%, 99%, 99%, 99%, and 99%, respectively.

Conclusions:

Bayesian analysis of the TAILOR-PCI trial provides clinically meaningful data on the posterior probability of reducing MACE using genotype-guided P2Y 12 inhibitor therapy after PCI.

Safety of Oral P2Y12 Inhibitors in Interventional Neuroradiology: Current Status and Perspectives

In the field of interventional neuroradiology, antiplatelet agents are commonly used to prepare patients before the implantation of permanent endovascular materials. Among the available drugs, clopidogrel is the most frequently used one, but resistance phenomena are considered to be relatively common. Prasugrel and ticagrelor were recently added to the pharmacologic arsenal, but the safety of these agents in patients undergoing neurointerventional procedures is still a subject of discussion. The cumulative experience with both drugs is less extensive than that with clopidogrel, and the experience with patients in the neurology field is less extensive than in the cardiology domain. In the present article, we provide a narrative review of studies that investigated safety issues of oral P2Y12 inhibitors in interventional neuroradiology and discuss potential routes for future research.

Translational Pharmacogenomics: Discovery, Evidence Synthesis and Delivery of Race-Conscious Medicine

Response to medications, the principal treatment modality for acute and chronic diseases, is highly variable, with 40-70% of patients exhibiting lack of efficacy or adverse drug reactions. With ~ 15-30% of this variability explained by genetic variants, pharmacogenomics has become a valuable tool in our armamentarium for optimizing treatments and is poised to play an increasing role in clinical care. This review presents the progress made toward elucidating genetic underpinnings of drug response including discovery of race/ancestry-specific pharmacogenetic variants and discusses the current evidence and evidence framework for actionability. The review is framed in the context of changing demographics and evolving views related to race and ancestry. Finally, it highlights the vital role played by cohort studies in elucidating genetic differences in drug response across race and ancestry and the informal collaborations that have enabled the field to bridge the "bench to bedside" translational gap.

Cilostazol Versus Aspirin for Secondary Stroke Prevention: Systematic Review and Meta-Analysis

OBJECTIVES

Cilostazol has promise as an alternative to aspirin for secondary stroke prevention given its vasodilatory and anti-inflammatory properties in addition to platelet aggregation inhibition. We aimed to conduct a systematic review and meta-analysis to estimate the efficacy and safety of cilostazol compared to aspirin for stroke prevention in patients with previous stroke or transient ischemic attack (TIA).

MATERIALS AND METHODS

We searched PubMed and the Cochrane Central Register of Controlled Trials from 1996 to 2019. Randomized clinical trials that compared cilostazol to aspirin and reported the endpoints of ischemic stroke, intracranial hemorrhage and any bleeding were included. A random-effects estimate was computed based on the Mantel-Haenszel method. The pooled risk estimates with 95% confidence intervals were compared between cilostazol and aspirin.

RESULTS

The search identified 5 randomized clinical trials comparing cilostazol vs. aspirin for secondary stroke prevention that collectively enrolled 7240 patients, all from Asian countries (3615 received cilostazol and 3625 received aspirin). Pooled results from the random-effects model showed that cilostazol was associated with significantly lower risk of recurrent ischemic stroke (RR 0.68; 95% CI, 0.54 to 0.87), intracranial hemorrhage (RR 0.42; 95% CI, 0.27 to 0.65) and any bleeding (RR 0.71; 95% CI, 0.55 to 0.91).

CONCLUSIONS

This meta-analysis suggests that cilostazol is more effective than aspirin in preventing recurrent ischemic stroke with lower risk of intracranial hemorrhage and other bleeding. Since all trials to date are from Asian countries, confirmatory trials of cilostazol for secondary stroke prevention in other populations are needed.

Pharmacokinetic, pharmacodynamic, and pharmacogenetic assays to monitor clopidogrel therapy

Clopidogrel is the most common and widely used antiplatelet agent for patients with coronary artery disease following confirmation by electrocardiographic studies. The nonresponsiveness of patients to clopidogrel and the possibility of testing for clopidogrel resistance by platelet function assays (PFA) are contentious issues. Light transmission aggregometry (LTA) is considered as the gold standard test among all PFA. In this review, the most commonly used PFA used for monitoring the effect of clopidogrel, LTA, vasodilator-stimulated phosphoprotein assay phosphorylation, rotational thromboelastometry (ROTEM) delta and ROTEM platelet, thromboelastography, PFA-100, VerifyNow P2Y12 assay, Multiplate analyzer, Plateletworks assay and pharmacogenetic studies, are comparatively discussed including their principles of action, advantages, and disadvantages. VerifyNow P2Y12 assay can be accepted as the ideal point of care test out of the discussed assays. However, modified assays are required which could overcome the limitations associated with currently available assays.

Prevalence and types of inconsistencies in clinical pharmacogenetic recommendations among major U.S. sources

Clinical implementation of pharmacogenomics (PGx) is slow. Previous studies have identified some inconsistencies among clinical PGx recommendations, but the prevalence and types of inconsistencies have not been comprehensively analyzed among major PGx guidance sources in the U.S. PGx recommendations from the Clinical Pharmacogenetics Implementation Consortium, U.S. Food and Drug Administration drug labels, and major U.S. professional medical organizations were analyzed through May 24, 2019. Inconsistencies were analyzed within the following elements: recommendation category; whether routine screening was recommended; and the specific biomarkers, variants, and patient groups involved. We identified 606 total clinical PGx recommendations, which contained 267 unique drugs. Composite inconsistencies occurred in 48.1% of clinical PGx recommendations overall, and in 93.3% of recommendations from three sources. Inconsistencies occurred in the recommendation category (29.8%), the patient group (35.4%), and routine screening (15.2%). In conclusion, almost one-half of clinical PGx recommendations from prominent U.S. guidance sources contain inconsistencies, which can potentially slow clinical implementation.

Effect of Genotype-Guided Oral P2Y12 Inhibitor Selection vs Conventional Clopidogrel Therapy on Ischemic Outcomes After Percutaneous Coronary Intervention: The TAILOR-PCI Randomized Clinical Trial

IMPORTANCE

After percutaneous coronary intervention (PCI), patients with CYP2C19*2 or *3 loss-of-function (LOF) variants treated with clopidogrel have increased risk of ischemic events. Whether genotype-guided selection of oral P2Y12 inhibitor therapy improves ischemic outcomes is unknown.

OBJECTIVE

To determine the effect of a genotype-guided oral P2Y12 inhibitor strategy on ischemic outcomes in CYP2C19 LOF carriers after PCI.

DESIGN, SETTING, AND PARTICIPANTS

Open-label randomized clinical trial of 5302 patients undergoing PCI for acute coronary syndromes (ACS) or stable coronary artery disease (CAD). Patients were enrolled at 40 centers in the US, Canada, South Korea, and Mexico from May 2013 through October 2018; final date of follow-up was October 2019.

INTERVENTIONS

Patients randomized to the genotype-guided group (n = 2652) underwent point-of-care genotyping. CYP2C19 LOF carriers were prescribed ticagrelor and noncarriers clopidogrel. Patients randomized to the conventional group (n = 2650) were prescribed clopidogrel and underwent genotyping after 12 months.

MAIN OUTCOMES AND MEASURES

The primary end point was a composite of cardiovascular death, myocardial infarction, stroke, stent thrombosis, and severe recurrent ischemia at 12 months. A secondary end point was major or minor bleeding at 12 months. The primary analysis was in patients with CYP2C19 LOF variants, and secondary analysis included all randomized patients. The trial had 85% power to detect a minimum hazard ratio of 0.50.

RESULTS

Among 5302 patients randomized (median age, 62 years; 25% women), 82% had ACS and 18% had stable CAD; 94% completed the trial. Of 1849 with CYP2C19 LOF variants, 764 of 903 (85%) assigned to genotype-guided therapy received ticagrelor, and 932 of 946 (99%) assigned to conventional therapy received clopidogrel. The primary end point occurred in 35 of 903 CYP2C19 LOF carriers (4.0%) in the genotype-guided therapy group and 54 of 946 (5.9%) in the conventional therapy group at 12 months (hazard ratio [HR], 0.66 [95% CI, 0.43-1.02]; P = .06). None of the 11 prespecified secondary end points showed significant differences, including major or minor bleeding in CYP2C19 LOF carriers in the genotype-guided group (1.9%) vs the conventional therapy group (1.6%) at 12 months (HR, 1.22 [95% CI, 0.60-2.51]; P = .58). Among all randomized patients, the primary end point occurred in 113 of 2641 (4.4%) in the genotype-guided group and 135 of 2635 (5.3%) in the conventional group (HR, 0.84 [95% CI, 0.65-1.07]; P = .16).

CONCLUSIONS AND RELEVANCE

Among CYP2C19 LOF carriers with ACS and stable CAD undergoing PCI, genotype-guided selection of an oral P2Y12 inhibitor, compared with conventional clopidogrel therapy without point-of-care genotyping, resulted in no statistically significant difference in a composite end point of cardiovascular death, myocardial infarction, stroke, stent thrombosis, and severe recurrent ischemia based on the prespecified analysis plan and the treatment effect that the study was powered to detect at 12 months.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01742117.

The efficacy and safety of CYP2C19 genotype-guided antiplatelet therapy compared with conventional antiplatelet therapy in patients with acute coronary syndrome or undergoing percutaneous coronary intervention: A meta-analysis of randomized controlled trials

Cytochrome P450 (CYP) 2C19 genotype is closely associated with the metabolism and efficacy of clopidogrel, thereby having an important impact on clinical outcomes of patients with acute coronary syndrome (ACS) or undergoing percutaneous coronary intervention (PCI). This study aimed to evaluate the efficacy and safety of CYP2C19 genotype-guided antiplatelet therapy in patients with ACS or undergoing PCI. PubMed, EMBASE, the Cochrane Library and clinicaltrials.gov were searched to identify randomized controlled trials (RCTs) comparing CYP2C19 genotype-guided antiplatelet therapy with conventional therapy in patients with ACS or undergoing PCI. Eight RCTs involving 6708 patients were included in this meta-analysis. CYP2C19 genotype-guided antiplatelet therapy was slightly superior to the conventional antiplatelet therapy in reducing the risk of MACE [RR(95%CI): 0.71(0.51-0.98), p = .04]. Meanwhile, the genotype-guided therapy group had significantly lower incidence of myocardial infarction [RR(95%CI): 0.56(0.40-0.78), p < .01], but similar risk of all-cause mortality, cardiovascular mortality, stent thrombosis, urgent revascularization and stroke compared to the conventional therapy group. Incidences of major/minor bleeding and major bleeding were comparable between the two groups. In patients with ACS or undergoing PCI, CYP2C19 genotype-guided antiplatelet therapy displayed benefit over conventional antiplatelet therapy in reducing the risk of MACE and myocardial infarction, without increasing bleeding risk. Further RCTs are needed to provide more evidences for CYP2C19 genotype-guided antiplatelet therapy.

Clopidogrel Pharmacogenetics

Common genetic variation in CYP2C19 (cytochrome P450, family 2, subfamily C, polypeptide 19) *2 and *3 alleles leads to a loss of functional protein, and carriers of these loss-of-function alleles when treated with clopidogrel have significantly reduced clopidogrel active metabolite levels and high on-treatment platelet reactivity resulting in increased risk of major adverse cardiovascular events, especially after percutaneous coronary intervention. The Food and Drug Administration has issued a black box warning advising practitioners to consider alternative treatment in CYP2C19 poor metabolizers who might receive clopidogrel and to identify such patients by genotyping. However, routine clinical use of genotyping for CYP2C19 loss-of-function alleles in patients undergoing percutaneous coronary intervention is not recommended by clinical guidelines because of lack of prospective evidence. To address this critical gap, TAILOR-PCI (Tailored Antiplatelet Initiation to Lessen Outcomes due to Decreased Clopidogrel Response After Percutaneous Coronary Intervention) is a large, pragmatic, randomized trial comparing point-of-care genotype-guided antiplatelet therapy with routine care to determine whether identifying CYP2C19 loss-of-function allele patients prospectively and prescribing alternative antiplatelet therapy is beneficial.

Antiaggregation effect of clopidogrel in coronary heart disease patients using omeprazole

Background Antiplatelet agents used in coronary heart disease (CHD) cause gastrointestinal side effects. Omeprazole can prevent and cure these antiplatelet side effects. Clopidogrel combined with aspirin increases the risk of gastrointestinal tract ulcers and bleeding. This research studied the effect of omeprazole on the antiplatelet effect of clopidogrel. Methods CHD patients using clopidogrel and aspirin receive omeprazole 20 mg in a single dose for 10 days. Platelet antiaggregation point for clopidogrel was measured using VerifyNow P2Y12. The cutoff points used were: low on treatment platelet reactivity (LPR) <85 P2Y12 reaction unit (PRU), normal on treatment platelet reactivity (NPR) 85-208 PRU, and high on treatment platelet reactivity (HPR) >208 PRU. Results Using the paired t-test PRU points pre- and post-omeprazole were 154 ± 85.89 PRU and 169.4 ± 56.15 PRU, respectively. The PRU points were consistent or decreased from the previous PRU points below the HPR cutoff (p: 0.215; >0.05). Before omeprazole use, five patients were categorized as NPR, two patients as LPR, and three patients as HPR. After omeprazole use, two patients, each from HPR and NPR category had a PRU point >208; the rest showed results below the HPR point. Conclusions In this study the PRU points of clopidogrel after omeprazole use showed a PRU <208. The hypothesis that omeprazole may reduce the antiaggregation effect of clopidogrel as shown by the increase in PRU above the cutoff points >208 PRU (HPR) was not proven.

Opportunities and Challenges in Cardiovascular Pharmacogenomics: From Discovery to Implementation

This review will provide an overview of the principles of pharmacogenomics from basic discovery to implementation, encompassing application of tools of contemporary genome science to the field (including areas of apparent divergence from disease-based genomics), a summary of lessons learned from the extensively studied drugs clopidogrel and warfarin, the current status of implementing pharmacogenetic testing in practice, the role of genomics and related tools in the drug development process, and a summary of future opportunities and challenges.

Clinical outcomes and predictive model of platelet reactivity to clopidogrel after acute ischemic vascular events

BACKGROUND

High on-treatment platelet reactivity (HTPR) has been suggested as a risk factor for patients with ischemic vascular disease. We explored a predictive model of platelet reactivity to clopidogrel and the relationship with clinical outcomes.

METHODS

A total of 441 patients were included. Platelet reactivity was measured by light transmittance aggregometry after receiving dual antiplatelet therapy. HTPR was defined by the consensus cutoff of maximal platelet aggregation >46% by light transmittance aggregometry. CYP2C19 loss-of-function polymorphisms were identified by DNA microarray analysis. The data were compared by binary logistic regression to find the risk factors. The primary endpoint was major adverse clinical events (MACEs), and patients were followed for a median time of 29 months. Survival curves were constructed with Kaplan-Meier estimates and compared by log-rank tests between the patients with HTPR and non-HTPR.

RESULTS

The rate of HTPR was 17.2%. Logistic regression identified the following predictors of HTPR: age, therapy regimen, body mass index, diabetes history, CYP2C192, or CYP2C193 variant. The area under the curve of receiver operating characteristic for the HTPR predictive model was 0.793 (95% confidence interval: 0.738-0.848). Kaplan-Meier analysis showed that patients with HTPR had a higher incidence of MACE than those with non-HTPR (21.1% vs. 9.9%; χ = 7.572, P = 0.010).

CONCLUSIONS

Our results suggest that advanced age, higher body mass index, treatment with regular dual antiplatelet therapy, diabetes, and CYP2C192 or CYP2C193 carriers are significantly associated with HTPR to clopidogrel. The predictive model of HTPR has useful discrimination and good calibration and may predict long-term MACE.

The effect of smoking on residual platelet reactivity to clopidogrel: a systematic review and meta-analysis

Cigarette smoking is an important cardiovascular risk factor, causing morbidity and mortality. There are many original studies on the impact of smoking, but its influence on platelet ADP-P2Y12 receptor inhibitors lack consistency. Thus, we conducted a systematic review and meta-analysis of already existing data/studies to further explore this issue. PubMed, Web of science, EMBASE, Clinical Trials, and the Cochrane Library were searched from inception to March 2018. Studies investigating the residual platelet reactivity categorized by smoking status and patients treated with platelet ADP-P2Y12 receptor inhibitors qualified the inclusion criteria. The primary outcome was P2Y12 reaction unit (PRU) value measured by VerifyNow P2Y12 assay, compared with different smoking status in ADP-P2Y12 receptor inhibitors treatment groups. Secondary outcome was post-treatment with 5 μmol/L ADP-inhibition of platelet aggregation (ADP-IPA) measured by light transmittance aggregometry (LTA). Of the 4954 citations retrieved, 12 studies involving 16 296 patients with acute coronary syndrome and/or stent deployment using platelet ADP-P2Y12 receptor inhibitors were included for meta-analysis. Pooled analysis revealed that PRU values of current smokers were 25.70 lower than nonsmokers (95% CI -38.81 to -12.60, p = 0.0001), getting better effects of antiplatelet treatment. In the smoking extent subgroup analysis, patients smoking >10 cigarettes/day shown about 46.49 lower of PRU values than patients smoking <10 cigarettes/day (p < 0.00001). Racial subgroup analyses found that smokers had increased platelet inhibition in the Caucasian population. Further, pooled analysis of ADP-IPA values for 1658 patients from five studies showed a significantly lower residual platelet reactivity in current smokers compared to that in nonsmokers (MD = -4.19; 95% CI -6.55 to -1.83; p = 0.0005). This systematic review and meta-analysis suggested that smokers have increased platelet inhibition and lower aggregation in response to clopidogrel than nonsmokers. These residual platelet reactivity observations may help to explain differential clinical outcomes in smokers vs. nonsmokers in large scale clinical trials.

Genetic Determinants of P2Y12 Inhibitors and Clinical Implications

There is significant interpatient variability in clopidogrel effectiveness, which is due in part to cytochrome P450 (CYP) 2C19 genotype. Approximately 30% of individuals carry CYP2C19 loss-of-function alleles, which have been consistently shown to reduce clopidogrel effectiveness after an acute coronary syndrome and percutaneous coronary intervention. Guidelines recommend consideration of prasugrel or ticagrelor in these patients. A clinical trial examining outcomes with CYP2C19 genotype-guided antiplatelet therapy is ongoing. In the meantime, based on the evidence available to date, several institutions have started clinically implementing CYP2C19 genotyping to assist with antiplatelet selection after percutaneous coronary intervention.

Implementing a personalized medicine program in a community health system

The implementation of a de novo personalized medicine program in a rural community health system serving an underserved population is described. Focusing on the safe use of drugs impacted by genetic variations in the non-oncology setting, we first addressed drug-gene pairs designated by the US FDA in black-box warnings (codeine, clopidogrel, abacavir, carbamazepine). The program's first success was a policy change to remove codeine from the pediatric formulary, rather than a testing recommendation. Pilot studies were then conducted with primary care providers to get them familiar with pharmacogenetic testing, and a consultative outpatient clinic for patients was developed. The assessment, planning, implementation, challenges, successes and lessons learned are described.

Does cardiology hold pharmacogenetics to an inconsistent standard? A comparison of evidence among recommendations

Current guideline recommendations for pharmacogenetic testing for clopidogrel by the American Heart Association/American College of Cardiology (AHA/ACC) contradict the Clinical Pharmacogenetics Implementation Consortium and the US FDA. The AHA/ACC recommends against routine pharmacogenetic testing for clopidogrel because no randomized controlled trials have demonstrated that testing improves patients' outcomes. However the AHA/ACC and the National Comprehensive Cancer Network (NCCN) recommend other pharmacogenetic tests in the absence of randomized controlled trials evidence. Using clopidogrel as a case example, we compared the evidence for other pharmacogenetic tests recommended by the AHA/ACC and NCCN. In patients that received percutaneous coronary intervention, the evidence supporting pharmacogenetic testing for clopidogrel is stronger than other pharmacogenetic tests recommended by the AHA/ACC and NCCN.

Pharmacogenetics in Cardiovascular Medicine

Considerable interindividual variability in response to cardiovascular pharmacotherapy exists with drug responses varying from being efficacious to inadequate to induce severe adverse events. Fueled by advancements and multidisciplinary collaboration across disciplines such as genetics, bioinformatics, and basic research, the vision of personalized medicine, rather than a one-size-fits-all approach, may be within reach. Pharmacogenetics offers the potential to optimize the benefit-risk profile of drugs by tailoring diagnostic and treatment strategies according to the individual patient. To date, a multitude of studies has tried to delineate the effects of gene-drug interactions for drugs commonly used to treat cardiovascular-related disease. The focus of this review is on how genetic variability may modify drug responsiveness and patient outcomes following therapy with commonly used cardiovascular drugs including clopidogrel, warfarin, statins, and β-blockers. Also included are examples of how genetic studies can be used to guide drug discovery and examples of how genetic information may be deployed in clinical decision making.

Association between CYP2C19 extensive metabolizer phenotype and childhood anti-reflux surgery following failed proton pump inhibitor medication treatment

When pediatric gastroesophageal reflux disease (GERD) that is refractory to proton pump inhibitor (PPI) medication treatment is identified in clinical practice and anti-reflux surgery (ARS) is being considered, genetic factors related to PPI metabolism by the CYP2C19 enzyme are currently not part of the clinical decision-making process. Our objective was to test the hypothesis that the distribution of the extensive metabolizer (EM) phenotypes among children undergoing ARS after failing PPI therapy would differ compared to controls (children with no history of ARS). We conducted a case-control study between children across the Nemours Health System from 2000 to 2014 who received ARS after failing PPI therapy and a control group comprised of healthy children. Our results demonstrated 2.9% of ARSs vs 20.8% of controls were poor metabolizers (PMs), 55.9% of ARSs vs 49.0% of controls were normal metabolizers (NMs), and 41.2% of ARSs vs 30.2% of controls were EMs; p = 0.035. Next, we performed a multiple-regression model to account for race as a potential confounding variable and the EM group was significantly associated with ARS compared to controls (OR 9.78, CI 1.25-76.55, p < 0.03).

CONCLUSION

Among children with medically refractory GERD despite PPI therapy, carriage of CYP2C19*17 allele corresponding to the EM phenotype was associated with ARS. Prospective comparative personalized medicine effectiveness studies are needed to determine if CYP2C19 genotype-guided dosing improves response to PPI therapy without a corresponding increase in adverse effects in children. What is known: • Anti-reflux surgery (ARS) is one of the most common surgical procedures performed in children for the indication of refractory gastroesophageal reflux disease (GERD). What is new: • Individualizing PPI medication dosing based on CYP2C19 diplotype may avoid GERD treatment failures and reduce the need for anti-reflux surgery (ARS).

Analysis of CYP2C19 Genetic Polymorphism in a Large Ethnic Hakka Population in Southern China

Background

Cytochrome P450 (CYP) 2C19 is an enzyme involved in the bioactivation of various important therapeutic drugs, from pro-drugs to an active inhibitor of platelet action. Variants in the CYP2C19 gene influence the pharmacokinetics and clinical response to antiplatelet drugs such as clopidogrel; however, there is no available data about the genetic variation of CYP2C19 in the Hakka population in China.

Material/Methods

A total of 6686 unrelated participants (ages 17–98 years) of self-reported Hakka ancestry admitted at an inpatient department in a hospital in southern China were successfully genotyped by the gene chip platform.

Results

The identified allele frequencies were CYP2C19*1 (64.33%), *2 (31.06%) and *3 (4.61%). The major prevalent genotype combinations were CYP2C19 *1/*1 (41.73%) and *1/*2 (39.65%). The distribution of CYP2C19 phenotypes was divided into extensive metabolizers (EM) (41.73%), intermediate metabolizers (IM) (45.21%), and poor metabolizers (PM) (13.06%). In the Hakka population, frequencies of the CYP2C19 *2 and *3 variants were observed to be close to those previously identified in Chinese and several other Asian populations.

Conclusions

Our study is the first to report on CYP2C19 polymorphisms in the Hakka population, and may help to optimize pharmacotherapy effectiveness by providing personalized medicine to this ethnic group in the near future.

Platelet function variability and non-genetic causes

Dual antiplatelet therapy (DAPT) has been established for the treatment of coronary artery disease, especially in and after acute coronary syndromes, and after coronary interventions. Data suggest that a significant percentage of individuals treated with clopidogrel do not receive the expected therapeutic benefit because of a decreased responsiveness of their platelets, which is caused by several extrinsic and intrinsic mechanisms. The clinical consequence of clopidogrel non-responsiveness is severe cardiovascular complications. Besides genetic variability in response to antiplatelet therapy, non-genetic causes such as drug interactions (proton-pump inhibitors, statins, calcium-channel blockers, coumarine derivates, antibiotics, antimycotics) and co-morbidities (diabetes mellitus, renal failure, obesity) are responsible for this phenomenon. Large clinical trials with standardised laboratory methods and hard clinical endpoints are needed to identify these interactions with clopidogrel and predictors for its non-responsiveness.

High platelet reactivity and clinical outcome – Fact and fiction

In patients suffering from acute coronary syndromes or undergoing percutaneous coronary intervention, oral antiplatelet treatment is routinely administered with the primary aim of inhibiting platelet-mediated thrombus formation and subsequent abrupt vessel occlusion. Simultaneous inhibition of blood platelet cyclooxygenase-1 by aspirin and of the P2Y12 receptor by clopidogrel or prasugrel is currently recommended in this setting. Inter-individual response variability to aspirin and especially to clopidogrel is the subject of much debate as evidence has grown over the years linking an attenuated response to treatment with the occurrence of ischaemic events. Consequently, the clinical entity of high (on-treatment) platelet reactivity (HPR) was born and subsequently characterised in numerous studies over the last decade. Until recently, alternative treatment options were limited in patients exhibiting HPR. At present the antiplatelet therapy landscape is changing with the advent of prasugrel and ticagrelor as alternative and more potent treatment options. Different tests for monitoring platelet function are available and are being increasingly employed in research projects and clinical routine. These tests may prove useful for achieving optimal platelet inhibition for the individual patient, and several centres now incorporate such testing in day-to-day practice. Widespread adoption of this practice and incorporation into clinical guidelines awaits the results of ongoing trials in which treatment is changed based on platelet function monitoring. This review aims to summarise available facts and fiction in relation to platelet function testing and reactivity with a particular focus on P2Y12 receptor inhibition in patients undergoing coronary stent placement.

Personalizing antiplatelet prescribing using genetics for patients undergoing percutaneous coronary intervention

INTRODUCTION

Clopidogrel is commonly prescribed with aspirin to reduce the risk for adverse cardiovascular events after percutaneous coronary intervention (PCI). However, there is significant inter-patient variability in clopidogrel response. The CYP2C19 enzyme is involved in the biotransformation of clopidogrel to its pharmacologically active form, and variation in the CYP2C19 gene contributes to clopidogrel response variability. Areas covered. This article describes the impact of CYP2C19 genotype on clopidogrel pharmacokinetics, pharmacodynamics, and effectiveness. Examples of clinical implementation of CYP2C19 genotype-guided antiplatelet therapy for patients undergoing PCI are also described as are emerging outcomes data with this treatment approach. Expert commentary. A large clinical trial evaluating outcomes with CYP2C19 genotype-guided antiplatelet therapy after PCI is on-going. In the meantime, data from pragmatic and observational studies and smaller trials support improved outcomes with genotyping after PCI and use of alternative antiplatelet therapy in patients with a CYP2C19 genotype associated with reduced clopidogrel effectiveness.

The Genetics of Ischemic Heart Disease: From Current Knowledge to Clinical Implications

Ischemic heart disease continues to cause high morbidity and mortality. Its prevalence is expected to increase due to population aging, and its prevention is a major goal of health policies. The risk of developing ischemic heart disease is related to a complex interplay between genetic, environmental, and lifestyle factors. In the last decade, considerable progress has been made in knowledge of the genetic architecture of this disease. This narrative review provides an overview of current knowledge of the genetics of ischemic heart disease and of its translation to clinical practice: identification of new therapeutic targets, assessment of the causal relationship between biomarkers and disease, improved risk prediction, and identification of responders and nonresponders to specific drugs (pharmacogenomics).

Precision Medicine at the University of Alabama at Birmingham: Laying the Foundational Processes Through Implementation of Genotype-Guided Antiplatelet Therapy

Precision medicine entails tailoring treatment based on patients' unique characteristics. As drug therapy constitutes the cornerstone of treatment for most chronic diseases, pharmacogenomics (PGx), the study of genetic variation influencing individual response to drugs, is an important component of precision medicine. Over the past decade investigations have identified genes and single-nucleotide polymorphisms (SNPs) and quantified their effect on drug response. Parallel development of point-of-care (POC) genotyping platforms has enabled the interrogation of the genes/SNPs within a timeline conducive to the provision of care. Despite these advances, the pace of integration of genotype-guided drug therapy (GGTx) into practice has faced significant challenges. These include difficulty in identifying SNPs with sufficiently robust evidence to guide clinical decision making, lack of clinician training on how to order and use genotype data, lack of clinical decision support (CDS) to guide treatment, and limited reimbursement. The University of Alabama at Birmingham's (UAB) efforts in precision medicine were initiated to address these challenges and improve the health of the racially diverse patients we treat.

Optimal pediatric dosing of anti-platelet agents for pipeline stent embolization -a case report and review of the literature

BACKGROUND

Various strategies are emerging for dosing antiplatelet therapies in preparation for pipeline stent embolization in adults. Hyper-response is associated with hemorrhagic complications. Hypo-response is associated with thromboembolic events. Dosing of antiplatelet agents is highly variable, with little consensus among experts for adults-and even more so for children. To date, pipeline stents have been deployed in 11 pediatric patients, ages 4-15. A variety of clopidogrel and aspirin dosing regimens have been used, with response tested in only three patients, who were all therapeutic. Thrombotic events occurred in two patients, neither of whom were tested.

CASE

We describe here the first case of a hemorrhagic complication in a hyper-responsive pediatric patient undergoing placement of a pipeline stent.

DISCUSSION

As the use of endovascular therapies requiring dual anti-platelet agents becomes more established, there is an increasing need to develop titration protocols that minimizes the risk of thrombotic and hemorrhagic events.

The CYP2C19*2 and CYP2C19*17 Polymorphisms play a Vital Role in Clopidogrel Responsiveness after Percutaneous Coronary Intervention: A Pharmacogenomics Study

Clopidogrel inhibits platelet activation and aggregation by blocking the P2Y₁₂ receptor. Dual antiplatelet therapy with clopidogrel and aspirin is recommended treatment by current guidelines for patients undergoing percutaneous interventions. Recurrent ischaemic cardiac events after this treatment showed lack of clopidogrel responsiveness. We aimed to investigate the most noticeable variants in the genes involved in clopidogrel pharmacokinetics and pharmacodynamics. A total of 347 Turkish patients who underwent percutaneous coronary interventions with stent implantation were included in our study. Platelet reactivity (PRU) and % inhibition were measured with VerifyNow P2Y₁₂ assay in blood samples collected from patients who took a standard dose of clopidogrel (75 mg/day) for at least 7 days. The variants in the CYP2C19, CYP3A4, CYP2B6, ABCB1, ITGB3 and PON1 genes were genotyped using the Sequenom MassARRAY system. When grouped, the patients with PRU values >208 as non-responsiveness to clopidogrel therapy; 104 (30%) patients were non-responders and 243 (70%) patients were responders. A significant association was found between the CYP2C19*2 (G636A) polymorphism and non-responsiveness to clopidogrel therapy (p < 0.001). An allele frequency of this single nucleotide polymorphism was high in non-responders; its odds ratio was 2.92 compared with G allele (p < 0.001). PRU values of CT genotypes were lower (p = 0.029) and % inhibition values of CT genotypes were higher (p = 0.008) compared with CC genotypes for the CYP2C19*17 (C806T) polymorphism. None of the other genetic variants were found to be statistically associated with non-responsiveness to clopidogrel and antiplatelet activity. Our findings suggest that the CYP2C19*2 polymorphism is associated with non-responsiveness to clopidogrel therapy and the CYP2C19*17 polymorphism enhances antiplatelet activity of clopidogrel. Depending on haplotypes of these two polymorphisms, clopidogrel-treated patients can be protected or not from stent thrombosis and ischaemic events.

Pharmacokinetic and Pharmacodynamic Responses to Clopidogrel: Evidences and Perspectives

Clopidogrel has significantly reduced the incidence of recurrent atherothrombotic events in patients with acute coronary syndrome (ACS) and in those undergoing percutaneous coronary intervention (PCI). However, recurrence events still remain, which may be partly due to inadequate platelet inhibition by standard clopidogrel therapy. Genetic polymorphisms involved in clopidogrel’s absorption, metabolism, and the P2Y12 receptor may interfere with its antiplatelet activity. Recent evidence indicated that epigenetic modification may also affect clopidogrel response. In addition, non-genetic factors such as demographics, disease complications, and drug-drug interactions can impair the antiplatelet effect of clopidogrel. The identification of factors contributing to the variation in clopidogrel response is needed to improve platelet inhibition and to reduce risk for cardiovascular events. This review encompasses the most recent updates on factors influencing pharmacokinetic and pharmacodynamic responses to clopidogrel.

Genomic translational research: Paving the way to individualized cardiac functional analyses and personalized cardiology

For most of Medicine's past, the best that physicians could do to cope with disease prevention and treatment was based on the expected response of an average patient. Currently, however, a more personalized/precise approach to cardiology and medicine in general is becoming possible, as the cost of sequencing a human genome has declined substantially. As a result, we are witnessing an era of precipitous advances in biomedicine and bourgeoning understanding of the genetic basis of cardiovascular and other diseases, reminiscent of the resurgence of innovations in physico-mathematical sciences and biology-anatomy-cardiology in the Renaissance, a parallel time of radical change and reformation of medical knowledge, education and practice. Now on the horizon is an individualized, diverse patient-centered, approach to medical practice that encompasses the development of new, gene-based diagnostics and preventive medicine tactics, and offers the broadest range of personalized therapies based on pharmacogenetics. Over time, translation of genomic and high-tech approaches unquestionably will transform clinical practice in cardiology and medicine as a whole, with the adoption of new personalized medicine approaches and procedures. Clearly, future prospects far outweigh present accomplishments, which are best viewed as a promising start. It is now essential for pluridisciplinary health care providers to examine the drivers and barriers to the clinical adoption of this emerging revolutionary paradigm, in order to expedite the realization of its potential. So, we are not there yet, but we are definitely on our way.

Clinical Value of CYP2C19 Genetic Testing for Guiding the Antiplatelet Therapy in a Chinese Population

OBJECTIVE

To compare the clinical effects between individual antiplatelet therapy guided by CYP2C19 genetic testing and conventional dual antiplatelet therapy in patients with coronary artery disease after percutaneous coronary intervention.

METHODS

In total of 628 coronary artery disease patients who had undergone successful percutaneous coronary intervention were included in this study. Patients were consecutively divided into routine group (n = 319) and individual group (n = 309) because of weather received CYP2C19 genetic testing. The individual group was divided again into extensive metabolizer group, intermediate metabolizer group, and poor metabolizer group according to CYP2C19 genotype. Then extensive metabolizer group received 75 mg daily of clopidogrel, intermediate metabolizer group received 150 mg daily of clopidogrel, and poor metabolizer group received ticagrelor 90 mg twice daily. Routine group was treated with clopidogrel 75 mg daily conventionally. The primary end points were defined as major adverse cardiovascular events (MACE), namely a composite of death from any cause, myocardial infarction, or target vessel revascularization. Safety end points were bleeding events classified by GUSTO.

RESULTS

All the 628 patients were followed for an average of 12 months and clinical outcomes were analyzed at 1, 6, and 12 months after discharge. The morbidity rates of MACE in individual group were all lower than those in routine group at 1, 6, and 12 months (1.3% vs. 5.6%, P = 0.003; 3.2% vs. 7.8%, P = 0.012; 4.2% vs. 9.4%, P = 0.010). No significant difference in the rates of bleeding was found between the 2 groups (P > 0.05). Even performed a multivariate logistic regression analysis, the benefit of individual antiplatelet therapy remained.

CONCLUSION

Individual antiplatelet therapy guided by CYP2C19 genetic testing significantly reduced the rate of MACE without an increase in the rate of bleeding in the near term in this Chinese population.

Diffuse Alveolar Hemorrhage in Patients Undergoing Neurointervention: A Case Report

INTRODUCTION

Diffuse alveolar hemorrhage (DAH) is a very rare complication but acute and life-threatening event. Clopidogrel has generally administered for neurointerventional surgery, but there were no reports of DAH related to clopidogrel in patients undergoing neurointervention.

CASE PRESENTATION

A 70-year-old male presented with DAH associated with clopidogrel after transfemoral cerebral angiography and coil embolization for cerebral aneurysm. The chest radiography showed bilateral symmetric peribronchial consolidation and bronchoscopy revealed diffuse hemorrhage on the bronchial wall at the bilateral lung. Clopidogrel was withdrawn and mechanical ventilation was applied for postoperative three days.

CONCLUSIONS

Small dose of clopidogrel (75 mg) may lead to rare, life-threatening DAH, so physicians should be aware of the possibility of DAH after neurointervention in patients who have respiratory distress, worsening alveolar infiltrates accompanied by hemoptysis.