Variability in responsiveness to oral antiplatelet therapy

The Role of Cilostazol, a Phosphodiesterase-3 Inhibitor, in the Development of Atherosclerosis and Vascular Biology: A Review with Meta-Analysis

Atherosclerotic cardiovascular disease (ASCVD) stands as the leading global cause of mortality. Addressing this vital and pervasive condition requires a multifaceted approach, in which antiplatelet intervention plays a pivotal role, together with antihypertensive, antidiabetic, and lipid-lowering therapies. Among the antiplatelet agents available currently, cilostazol, a phosphodiesterase-3 inhibitor, offers a spectrum of pharmacological effects. These encompass vasodilation, the impediment of platelet activation and aggregation, thrombosis inhibition, limb blood flow augmentation, lipid profile enhancement through triglyceride reduction and high-density lipoprotein cholesterol elevation, and the suppression of vascular smooth muscle cell proliferation. However, the role of cilostazol has not been clearly documented in many guidelines for ASCVD. We comprehensively reviewed the cardiovascular effects of cilostazol within randomized clinical trials that compared it to control or active agents and involved individuals with previous coronary artery disease or stroke, as well as those with no previous history of such conditions. Our approach demonstrated that the administration of cilostazol effectively reduced adverse cardiovascular events, although there was less evidence regarding its impact on myocardial infarction. Most studies have consistently reported its favorable effects in reducing intermittent claudication and enhancing ambulatory capacity in patients with peripheral arterial disease. Furthermore, cilostazol has shown promise in mitigating restenosis following coronary stent implantation in patients with acute coronary syndrome. While research from more diverse regions is still needed, our findings shed light on the broader implications of cilostazol in the context of atherosclerosis and vascular biology, particularly for individuals at high risk of ASCVD.

Using the PEAR1 Polymorphisms Rs12041331 and Rs2768759 as Potential Predictive Markers of 90-Day Bleeding Events in the Context of Minor Strokes and Transient Ischemic Attack

In this study, we explored the relationship between the platelet endothelial aggregation receptor 1 (PEAR1) polymorphisms, platelet reactivity, and clinical outcomes in patients with minor stroke or transient ischemic attack (TIA). Randomized controlled trial subgroups were assessed, wherein patients received dual antiplatelet therapy for at least 21 days. Platelet reactivity was measured at different time intervals. Genotypes were categorized as wild-type, mutant heterozygous, and mutant homozygous. Clinical outcomes were evaluated after 90 days. The rs12041331 polymorphism predominantly influenced adenosine diphosphate channel platelet activity, with the AA genotype displaying significantly lower residual platelet activity to the P2Y12 response unit (p < 0.01). This effect was more evident after 7 days of dual antiplatelet treatment (p = 0.016). Mutant A allele carriers had decreased rates of recurrent stroke and complex endpoint events but were more prone to bleeding (p = 0.015). The rs2768759 polymorphism majorly impacted arachidonic acid (AA) channel platelet activity, which was particularly noticeable in the C allele carriers. Our regression analysis demonstrated that rs12041331 AA + GA and rs2768759 CA predicted 90-day post-stroke bleeding. In conclusion, the PEAR1 polymorphisms rs12041331 and rs2768759 interfere with platelet aggregation and the performance of antiplatelet drugs. These genetic variations may contribute to bleeding events associated with minor stroke and TIA.

Personalised antiplatelet therapies for coronary artery disease: what the future holds

Coronary artery disease (CAD) is one of the leading causes of death globally, and antiplatelet therapy is crucial for both its prevention and treatment. Antiplatelet drugs such as aspirin and P2Y12 inhibitors are commonly used to reduce the risk of thrombotic events, including myocardial infarction, stroke, and stent thrombosis. However, the benefits associated with the use of antiplatelet drugs also come with a risk of bleeding complications. The ever-growing understanding of the poor prognostic implications associated with bleeding has set the foundations for defining strategies that can mitigate such safety concern without any trade-off in antithrombotic protection. To this extent, personalised antiplatelet therapy has emerged as a paradigm that optimizes the balance between safety and efficacy by customizing treatment to the individual patient's needs and risk profile. Accurate risk stratification for both bleeding and thrombosis can aid in selecting the optimal antiplatelet therapy and prevent serious and life-threatening outcomes. Risk stratification has traditionally included clinical and demographic characteristics and has expanded to incorporate angiographic features and laboratory findings. The availability of bedside platelet function testing as well as rapid genotyping assays has also allowed for a more individualized selection of antiplatelet therapy. This review provides a comprehensive overview of the current state of the art and future trends in personalised antiplatelet therapy for patients with CAD, with emphasis on those presenting with an acute coronary syndrome and undergoing percutaneous coronary revascularization. The aim is to provide clinicians with a comprehensive understanding of personalised antiplatelet therapy and facilitate informed clinical decision-making.

Structure-Activity Relationship Analysis of Rhosin, a RhoA GTPase Inhibitor, Reveals a New Class of Antiplatelet Agents

Current antiplatelet therapies have several clinical complications and are mostly irreversible in terms of suppressing platelet activity; hence, there is a need to develop improved therapeutic agents. Previous studies have implicated RhoA in platelet activation. Here, we further characterized the lead RhoA inhibitor, Rhosin/G04, in platelet function and present structure-activity relationship (SAR) analysis. A screening for Rhosin/G04 analogs in our chemical library by similarity and substructure searches revealed compounds that showed enhanced antiplatelet activity and suppressed RhoA activity and signaling. A screening for Rhosin/G04 analogs in our chemical library using similarity and substructure searches revealed compounds that showed enhanced antiplatelet activity and suppressed RhoA activity and signaling. SAR analysis revealed that the active compounds have a quinoline group optimally attached to the hydrazine at the 4-position and halogen substituents at the 7- or 8-position. Having indole, methylphenyl, or dichloro-phenyl substituents led to better potency. Rhosin/G04 contains a pair of enantiomers, and S-G04 is significantly more potent than R-G04 in inhibiting RhoA activation and platelet aggregation. Furthermore, the inhibitory effect is reversible, and S-G04 is capable of inhibiting diverse-agonist-stimulated platelet activation. This study identified a new generation of small-molecule RhoA inhibitors, including an enantiomer capable of broadly and reversibly modulating platelet activity.

Cilostazol: a Review of Basic Mechanisms and Clinical Uses

Primarily used in the treatment of intermittent claudication, cilostazol is a 2-oxyquinolone derivative that works through the inhibition of phosphodiesterase III and related increases in cyclic adenosine monophosphate (cAMP) levels. However, cilostazol has been implicated in a number of other basic pathways including the inhibition of adenosine reuptake, the inhibition of multidrug resistance protein 4, among others. It has been observed to exhibit antiplatelet, antiproliferative, vasodilatory, and ischemic-reperfusion protective properties. As such, cilostazol has been investigated for clinical use in a variety of settings including intermittent claudication, as an adjunctive for reduction of restenosis after coronary and peripheral endovascular interventions, and in the prevention of secondary stroke, although its widespread implementation for indications other than intermittent claudication has been limited by relatively modest effect sizes and lack of studies in western populations. In this review, we highlight the pleiotropic effects of cilostazol and the evidence for its clinical use.

P2Y12 Antiplatelet Choice for Patients with Chronic Kidney Disease and Acute Coronary Syndrome: A Systematic Review and Meta-Analysis

This study aims to evaluate potentially appropriate antiplatelet therapy in patients with chronic kidney disease. A systematic analysis was conducted to identify the clinical outcomes of available antiplatelet therapy regimens with enhanced platelet inhibition activity (intervention of 5 regimens) over the standard dose of clopidogrel-based dual antiplatelet therapy in patients with renal insufficiency. An electronic keyword search was performed on Pubmed, Embase, and Cochrane Library per PRISMA guidelines. We performed a prespecified net clinical benefit analysis (a composite of the rates of all-cause or cardiac-related death, myocardial infarction, major adverse cardiac outcomes, and minor and major bleeding), and included 12 studies. The intervention substantially lowered the incidence of all-cause mortality (RR 0.67; p = 0.003), major adverse cardiac outcomes (RR 0.79; p < 0.00001), and myocardial infarction (RR 0.28; p = 0.00007) without major bleeding (RR 1.14; p = 0.33) in patients with renal insufficiency, but no significant differences were noticed with cardiac-related mortality and stent thrombosis. The subgroup analysis revealed substantially elevated bleeding risk in patients with severe renal insufficiency or on hemodialysis (RR 1.68; p = 0.002). Our study confirmed that the intervention considerably enhances clinical outcomes in patients with renal insufficiency, however, a standard dose of clopidogrel-based antiplatelet therapy is favorable in patients with severe renal insufficiency.

The association of body mass index with long-term clinical outcomes after ticagrelor monotherapy following abbreviated dual antiplatelet therapy in patients undergoing percutaneous coronary intervention: a prespecified sub-analysis of the GLOBAL LEADERS Trial

Background

The efficacy of antiplatelet therapies following percutaneous coronary intervention (PCI) may be affected by body mass index (BMI).

Methods and results

This is a prespecified subgroup analysis of the GLOBAL LEADERS trial, a prospective, multicenter, open-label, randomized controlled trial in an all-comer population undergoing PCI, comparing the experimental strategy (23-month ticagrelor monotherapy following 1-month dual antiplatelet therapy [DAPT]) with a reference regimen (12-month aspirin monotherapy following 12-month DAPT). A total of 15,968 patients were stratified by baseline BMI with prespecified threshold of 27 kg/m². Of those, 6973 (43.7%) patients with a BMI < 27 kg/m² had a higher risk of all-cause mortality at 2 years than those with BMI ≥ 27 kg/m² (adjusted HR 1.24, 95% CI 1.02–1.49). At 2 years, the rates of the primary endpoint (all-cause mortality or new Q-wave myocardial infarction) were similar between treatment strategies in either BMI group (p_interaction = 0.51). In acute coronary syndrome, however, the experimental strategy was associated with significant reduction of the primary endpoint compared to the reference strategy in patients with BMI < 27 kg/m² (HR 0.69, 95% CI 0.51–0.94), but not in the ones with BMI ≥ 27 kg/m² (p_interaction = 0.047). In chronic coronary syndrome, there was no between-group difference in the efficacy and safety of the two antiplatelet strategies.

Conclusions

Overall, BMI did not influence the treatment effect seen with ticagrelor monotherapy; however, a beneficial effect of ticagrelor monotherapy was seen in ACS patients with BMI < 27 kg/m².

Trial registration

The trial has been registered with ClinicalTrials.gov, Number NCT01813435.

Graphic abstract

Electronic supplementary material

The online version of this article (10.1007/s00392-020-01604-1) contains supplementary material, which is available to authorized users.

Assessment of Platelet REACtivity After Transcatheter Aortic Valve Replacement: The REAC-TAVI Trial

OBJECTIVES

The REAC-TAVI (Assessment of platelet REACtivity after Transcatheter Aortic Valve Implantation) trial enrolled patients with aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR) pre-treated with aspirin + clopidogrel, aimed to compare the efficacy of clopidogrel and ticagrelor in suppressing high platelet reactivity (HPR) after TAVI.

BACKGROUND

Current recommendations support short-term use of aspirin + clopidogrel for patients with severe AS undergoing TAVR despite the lack of compelling evidence.

METHODS

This was a prospective, randomized, multicenter investigation. Platelet reactivity was measured at 6 different time points with the VerifyNow assay (Accriva Diagnostics, San Diego, California). HPR was defined as (P2Y₁₂ reaction units (PRU) ≥208. Patients with HPR before TAVR were randomized to either aspirin + ticagrelor or aspirin + clopidogrel for 3 months. Patients without HPR continued with aspirin + clopidogrel (registry cohort). The primary endpoint was non-HPR status (PRU <208) in ≥70% of patients treated with ticagrelor at 90 days post-TAVR.

RESULTS

A total of 68 patients were included. Of these, 48 (71%) had HPR (PRU 273 ± 09) and were randomized to aspirin + ticagrelor (n = 24, PRU 277 ± 08) or continued with aspirin + clopidogrel (n = 24, PRU 269 ± 49). The remaining 20 patients (29%) without HPR (PRU 133 ± 12) were included in the registry. Overall, platelet reactivity across all the study time points after TAVR was lower in patients randomized to ticagrelor compared with those treated with clopidogrel, including those enrolled in the registry (p < 0.001). The primary endpoint was achieved in 100% of patients with ticagrelor compared with 21% with clopidogrel (p < 0.001). Interestingly, 33% of clopidogrel responder patients at baseline developed HPR status during the first month after TAVR.

CONCLUSIONS

HPR to clopidogrel is present in a considerable number of patients with AS undergoing TAVR. Ticagrelor achieves a better and faster effect, providing sustained suppression of HPR to these patients. (Platelet Reactivity After TAVI: A Multicenter Pilot Study [REAC-TAVI]; NCT02224066).

Effects of PON1 Gene Promoter DNA Methylation and Genetic Variations on the Clinical Outcomes of Dual Antiplatelet Therapy for Patients Undergoing Percutaneous Coronary Intervention

INTRODUCTION AND OBJECTIVE

The relationship between either paraoxonase 1 (PON1) gene promoter DNA methylation or genetic variations and bleeding or major adverse cardiac events after dual antiplatelet therapy has been incompletely characterized. We aimed to systematically investigate the role of genetic variations and DNA methylation of the PON1 CpG island promoter on the clinical outcomes of dual antiplatelet therapy for patients with coronary artery disease (CAD) who underwent percutaneous coronary intervention (PCI).

METHODS

This study included 653 patients with CAD undergoing PCI and receiving dual antiplatelet therapy. Genomic DNAs were isolated from whole blood and were genotyped for the three single nucleotide polymorphisms (SNPs) of the PON1 gene. The DNA methylation levels in the PON1 promoter region were determined by bisulfite sequencing or pyrosequencing at five CpG sites (positions -142, -161, -163, -170, and -184 from the transcription start site). Clopidogrel and its metabolites in plasma were examined using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), and platelet function analysis was performed using the VerifyNow assay.

RESULTS

Statistically significant associations between methylation levels at five PON1 CpG sites and bleeding were observed: -184 [odds ratio (OR) 0.98, 95% confidence interval (CI) 0.96-1.00, p = 0.028]; -170 (OR 0.99, 95% CI 0.97-1.00, p = 0.048); -163 (OR 0.98, 95% CI 0.96-1.00, p = 0.029); -161 (OR 0.98, 95% CI 0.97-1.00, p = 0.026); and -142 (OR 0.98, 95% CI 0.97-1.00, p = 0.042) at a false discovery rate of <5%. Statistical analysis also revealed that aspirin reaction units (ARUs) were significantly associated with PON1 methylation level at CpG site -163 (p = 0.0342). The ARUs of patients with the PON1 126 CC genotype was 527 ± 94, which was higher than the ARUs (473 ± 89) of patients with the 126 CG genotype (p = 0.0163). Multivariate logistic regression analysis indicated that the PON1 methylation level at CpG site -161 (OR 0.95, 95% CI 0.92-0.98, p = 0.002) and the use of angiotensin-converting enzyme inhibitors (OR 0.48, 95% CI 0.26-0.89, p = 0.021) were associated with a decreased risk of bleeding events.

CONCLUSIONS

Hypomethylation of CpGs in the PON1 promoter may be a weak, albeit statistically significant, risk factor of bleeding after dual antiplatelet therapy. Further large-scale studies are needed to verify our results.

Shear-Dependent Platelet Aggregation: Mechanisms and Therapeutic Opportunities

Cardiovascular diseases (CVD) are the number one cause of morbidity and death worldwide. As estimated by the WHO, the global death rate from CVD is 31% wherein, a staggering 85% results from stroke and myocardial infarction. Platelets, one of the key components of thrombi, have been well-investigated over decades for their pivotal role in thrombus development in healthy as well as diseased blood vessels. In hemostasis, when a vascular injury occurs, circulating platelets are arrested at the site of damage, where they are activated and aggregate to form hemostatic thrombi, thus preventing further bleeding. However, in thrombosis, pathological activation of platelets occurs, leading to uncontrolled growth of a thrombus, which in turn can occlude the blood vessel or embolize, causing downstream ischemic events. The molecular processes causing pathological thrombus development are in large similar to the processes controlling physiological thrombus formation. The biggest challenge of anti-thrombotics and anti-platelet therapeutics has been to decouple the pathological platelet response from the physiological one. Currently, marketed anti-platelet drugs are associated with major bleeding complications for this exact reason; they are not effective in targeting pathological thrombi without interfering with normal hemostasis. Recent studies have emphasized the importance of shear forces generated from blood flow, that primarily drive platelet activation and aggregation in thrombosis. Local shear stresses in obstructed blood vessels can be higher by up to two orders of magnitude as compared to healthy vessels. Leveraging abnormal shear forces in the thrombus microenvironment may allow to differentiate between thrombosis and hemostasis and develop shear-selective anti-platelet therapies. In this review, we discuss the influence of shear forces on thrombosis and the underlying mechanisms of shear-induced platelet activation. Later, we summarize the therapeutic approaches to target shear-sensitive platelet activation and pathological thrombus growth, with a particular focus on the shear-sensitive protein von Willebrand Factor (VWF). Inhibition of shear-specific platelet aggregation and targeted drug delivery may prove to be much safer and efficacious approaches over current state-of-the-art antithrombotic drugs in the treatment of cardiovascular diseases.

The effect of the CYP2C19*2 allele on cardiovascular outcomes in patients with coronary artery stenting: a prospective study

INTRODUCTION

The aim of the study was to evaluate the effects of cytochrome P450 2C19*2 (CYP2C19*2) on ischemic and bleeding events in the Chinese Han population.

MATERIAL AND METHODS

Patients after coronary artery stenting were enrolled for genotyping CYP2C19*2. Platelet reactivity 4 weeks after stent implantation was compared between different genotype groups. Ischemic and bleeding events were compared after 6 months' follow-up.

RESULTS

A total of 255 patients were enrolled and 57.7% and 42.3% of patients presented with stable angina and acute coronary syndrome, respectively. The prevalence of homozygous (AA) and heterozygous (GA) CYP2C19*2 variants was 3.5% and 24.7% respectively, and the prevalence of wild type (GG) was 71.8%. Compared to GG and GA genotype groups, the absolute platelet activity reduction was significantly lower in AA genotype (GG 43.6 ±7.8%, GA 31.9 ±6.5%, and AA 24.8 ±5.3%, p < 0.01 for trend). After 6 months' follow-up, 3.3%, 4.8% and 11.1% of patients experienced ischemic events in GG, GA and AA genotype groups, respectively (p = 0.003 for trend). After adjusting for traditional risk factors, AA genotype was significantly associated with ischemic events, with hazard ratio 1.19 and 95% confidence interval 1.08-1.30 (p = 0.013). Also, 2.2%, 1.6% and 0% of patients experienced bleeding events in GG, GA and AA genotype groups (p = 0.153 for trend). No independent association of CYP2C19*2 genotype and bleeding events was observed.

CONCLUSIONS

Genotyping of CYP2C19*2 may be useful to guide antiplatelet treatment in the Chinese Han population. Randomized controlled trials are warranted to investigate whether genotype-guided antiplatelet treatment could reduce ischemic events.

Association between High Platelet Reactivity Following Dual Antiplatelet Therapy and Ischemic Events in Japanese Patients with Coronary Artery Disease Undergoing Stent Implantation

AIM

Although high on-treatment platelet reactivity (HTPR) with dual antiplatelet therapy (DAPT) correlates with long-term adverse outcomes in patients undergoing percutaneous coronary intervention, the correlation in Japanese patients remains unclear. Therefore, we examined the relationship between platelet reactivity during DAPT with aspirin and clopidogrel and 1-year clinical outcomes following successful coronary stent implantation.

METHODS

A prospective, multicenter registry study (j-CHIPS) was conducted in patients undergoing coronary stenting and receiving aspirin and clopidogrel at 16 hospitals in Japan. A VerifyNow point-of-care assay was used to assess platelet reactivity, and a cutoff value to define HTPR was established.

RESULTS

Between February 2011 and May 2013, 1047 patients were prospectively enrolled, of which 854 patients with platelet function evaluation at 12-24 h after PCI were included in the final analysis. After 1 year of follow-up, the incidence of the primary endpoint (a composite of all-cause mortality, myocardial infarction, stent thrombosis, and ischemic stroke) was significantly higher in patients with HTPR than in those without (5.9% vs. 1.5%, p=0.008), and HTPR showed a modest ability to discriminate between patients who did and did not experience major adverse cardiac and cerebrovascular events (area under the curve, 0.60; 95% confidence interval, 0.511-0.688, p=0.039). HTPR status did not identify patients at risk for major or minor bleeding events.

CONCLUSION

HTPR was significantly associated with adverse ischemic outcomes at 1 year after PCI in Japanese patients receiving maintenance DAPT, indicating its potential as a prognostic indicator of clinical outcomes in this high-risk patient population.

Bioptically Proven "Anticoagulation-Related Nephropathy" Induced by Dual Antiplatelet Therapy

Anticoagulation-related nephropathy (ARN) is a significant and underdiagnosed complication in patients who receive anticoagulation therapy. It is characterized by acute kidney injury in the setting of excessive anticoagulation defined as an international normalized ratio > 3.0 in patients treated with warfarin. A definitive diagnosis is made by renal biopsy showing acute tubular necrosis with obstruction of the tubuli by red blood cell casts. However, the evidence shows that ARN can occur during treatment with novel oral anticoagulants as well. Although it has been suggested that antiplatelet therapy, such as aspirin, might contribute to coagulopathy (and therefore the hypothetical risk of ARN), there are no reports of ARN induced by antiplatelet therapy according to our knowledge. It is also reported that glomerular lesions (i.e., kidney disease) represent a risk factor for ARN. We present a case of an 82-year-old man who developed biopsy-proven ARN after the administration of dual antiplatelet therapy with no previous anticoagulation treatment and normal coagulation tests.

Prior exposure to aspirin in acute coronary syndrome patients: a cardiovascular risk marker or a predictor of adverse outcome? A contemporary data of a national registry

Despite the known protective cardiovascular effect of aspirin, former studies identified its prior exposure to an acute coronary syndrome (ACS) as an independent risk factor for adverse events. However, those studies did not reflect contemporary approaches. In the current study, we determine whether patients exposed to aspirin before an ACS have a worse cardiovascular risk profile and if it predicts higher risk of recurrent cardiovascular events or mortality. A cohort of patients enrolled in a national registry of ACS was analyzed according to prior exposure to aspirin. A propensity score standardized patients according to baseline comorbidities. Multivariable COX regression analysis was performed in unmatched and matched populations for a primary endpoint (composite of all-cause mortality and/or cardiovascular rehospitalization) and two secondary endpoints (all-cause mortality and cardiovascular rehospitalization, separately) at 1-year follow-up. Among 5533 ACS patients, 1763 were previously exposed to aspirin. They were older and had more comorbidities; contemporary approaches, both coronary angiography and percutaneous coronary angioplasty were less likely to be performed. Before matching the population, prior exposure to aspirin was an independent predictor of primary composite endpoint (p = 0.002) and cardiovascular rehospitalization as the secondary endpoint (p = 0.001). There were no statistically significant differences between both groups in the multivariable model for the primary or secondary endpoints after matching. Previous exposure to aspirin identified ACS patients with worse baseline characteristics, establishing its role as a cardiovascular risk marker. However, our data do not support including aspirin pretreatment in risk stratification scores as an adverse prognostic variable.

SAFE (Sarpogrelate Anplone in Femoro-popliteal artery intervention Efficacy) study: study protocol for a randomized controlled trial

Background

Sarpogrelate is expected to reduce restenosis by protecting blood vessels from oxidative stress and vascular endothelial dysfunction as well as by acting as an antiplatelet agent after endovascular treatment (EVT). This trial was designed to compare aspirin plus sustained-release (SR) sarpogrelate with aspirin plus clopidogrel for the prevention of restenosis in patients with femoro-popliteal (FP) peripheral artery disease (PAD) who underwent EVT.

Methods/Design

This is an open label, multicenter, prospective randomized controlled clinical trial. Patients will be eligible for inclusion in this study if they require EVT for stenosis or occlusion of a de novo FP lesion. Patients in each group will receive aspirin 100 mg with clopidogrel 75 mg or aspirin 100 mg with SR sarpogrelate 300 mg (Anplone®) orally once a day for six months. The primary outcome of the study is the restenosis rate, defined as > 50% luminal reduction by computed tomography angiography or catheter angiography in the six-month follow-up period. Secondary outcomes include target lesion revascularization, major bleeding, ipsilateral major amputation, all-cause mortality, and all adverse events that take place in those six months.

Discussion

This study is a multicenter randomized controlled trial designed to show non-inferiority in terms of the re-stenosis rate of SR sarpogrelate compared to clopidogrel for EVT for PAD in FP lesion patients.

Trial registration

ClinicalTrials.gov, NCT02959606. Registered on 9 November 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2155-5) contains supplementary material, which is available to authorized users.

Recent developments and future directions for the use of pharmacogenomics in cardiovascular disease treatments

INTRODUCTION

Cardiovascular disease is still the leading cause of death worldwide. There are many environmental and genetic factors that play a role in the development of cardiovascular disease. The treatment of cardiovascular disease is beginning to move in the direction of personalized medicine by using biomarkers from the patient's genome to design more effective treatment plans. Pharmacogenomics have already uncovered many links between genetic variation and response of many different drugs. Areas covered: This article will focus on the main polymorphisms that impact the risk of adverse effects and response efficacy of statins, clopidogrel, aspirin, β-blockers, warfarin dalcetrapib and vitamin E. The genes discussed include SLCO1B1, ABCB1, CYP3A4, CYP3A5, CYP2C19, PTGS1, PTGS2, ADRB1, ADCY9, CYP2C19, PON1, CES1, PEAR1, GPIIIa, CYP2D6, CKORC1, CYP2C9 and Hp. Expert opinion: Although there are some convincing results that have already been incorporated in the labelling treatment guidelines, most gene-drug relationships have been inconsistent. A better understanding of the relationships between genetic factors and drug response will provide more opportunities for personalized diagnosis and treatment of cardiovascular disease.

Impact of CYP3A4*1G Allele on Clinical Pharmacokinetics and Pharmacodynamics of Clopidogrel

BACKGROUND AND OBJECTIVES

Resistance to the antiplatelet treatment with clopidogrel has both genetic and non-genetic causes. Polymorphic variants of cytochrome P450 3A4 isoenzyme involved in the bioactivation of clopidogrel might have an influence on responsiveness to the drug. The aim of this study was to evaluate the influence of CYP3A4*1G (IVS10+12G>A, rs2242480) on the pharmacokinetics and pharmacodynamics of clopidogrel.

METHODS

CYP3A4*1G polymorphism was determined in a group of 82 patients undergoing percutaneous coronary intervention and taking 75 mg of clopidogrel daily. Concentrations of clopidogrel and its metabolites, inactive carboxylic acid derivative and two diastereoisomers of active thiol metabolite: H3 and H4, were determined by a validated HPLC-MS/MS method. Pharmacodynamic effect was measured by an impedance method with a Multiplate analyzer. Moreover, an effect of factors, such as CYP2C19 phenotype, age, gender, body mass index and interactions with drugs metabolized by CYP3A4 were also investigated.

RESULTS

In the studied group allele frequencies were: wt-0.921, *1G-0.079. Pharmacokinetic parameters of clopidogrel and its metabolites were not significantly different in carriers of *1G allele, comparing to wt/wt homozygotes. Platelet aggregation was higher in heterozygotes than in wt/wt carriers; however, the difference was not statistically significant (p = 0.484). In a multivariate analysis, which included age, body mass index, co-morbidities and coadministered drugs, CYP3A4*1G was not a predictor of values of H3 and H4 pharmacokinetic parameters and platelet aggregation.

CONCLUSION

CYP3A4*1G might not be a significant contributor to the variability in pharmacokinetic and pharmacodynamic response to clopidogrel therapy.

Aspirin for Primary Cardiovascular Risk Prevention and Beyond in Diabetes Mellitus

Daily administration of low-dose aspirin has proved to be beneficial in preventing recurrent cardiovascular events. However, the role of aspirin for primary prevention in patients with no overt cardiovascular disease is more controversial. In fact, in lower risk patients, the modest benefit in reducing serious vascular events can be offset by the increased risk of bleeding, including intracranial and gastrointestinal hemorrhage. Diabetes mellitus has been associated with a substantially increased risk of both first and recurrent atherothrombotic events, which makes aspirin therapy of potential value in these subjects. Moving from general aspects of aspirin pharmacology and specific issues in diabetes mellitus, this article reviews the literature on the topic of aspirin for primary prevention in general, and in subjects with diabetes mellitus in particular, to culminate with arguments pro and con and a practical risk-based algorithm for aspirin initiation in daily practice.

Medicinal Plants with Antiplatelet Activity

Blood platelets play an essential role in the hemostasis and wound-healing processes. However, platelet hyperactivity is associated to the development and the complications of several cardiovascular diseases. In this sense, the search for potent and safer antiplatelet agents is of great interest. This article provides an overview of experimental studies performed on medicinal plants with antiplatelet activity available through literature with particular emphasis on the bioactive constituents, the parts used, and the various platelet signaling pathways modulated by medicinal plants. From this review, it was suggested that medicinal plants with antiplatelet activity mainly belong to the family of Asteraceae, Rutaceae, Fabaceae, Lamiaceae, Zygophyllaceae, Rhamnaceae, Liliaceae, and Zingiberaceae. The antiplatelet effect is attributed to the presence of bioactive compounds such as polyphenols, flavonoids, coumarins, terpenoids, and other substances which correct platelet abnormalities by interfering with different platelet signalization pathways including inhibition of the ADP pathway, suppression of TXA2 formation, reduction of intracellular Ca(2+) mobilization, and phosphoinositide breakdown, among others. The identification and/or structure modification of the plant constituents and the understanding of their action mechanisms will be helpful in the development of new antiplatelet agents based on medicinal plants which could contribute to the prevention of thromboembolic-related disorders by inhibiting platelet aggregation. Copyright © 2016 John Wiley & Sons, Ltd.

High maintenance dose of clopidogrel in patients with high on-treatment platelet reactivity after a percutaneous coronary intervention: a meta-analysis

OBJECTIVE

High on-treatment platelet reactivity (HTPR) has been linked to cardiovascular (CV) events after a percutaneous coronary intervention. There have been some controversies on whether a high maintenance dose (MD) of clopidogrel is effective for HTPR patients. Thus, we carried out a meta-analysis to assess the efficacy and safety of a high MD of clopidogrel in patients with HTPR.

METHODS

Searches of PubMed (from 1966 to May 2014), EMBASE (from 1974 to May 2014), and the Cochrane Library (2 May 2014) were performed. All randomized-controlled trials assessing the efficacy and safety of a high MD of clopidogrel in patients with HTPR were included.

RESULTS

A total of eight randomized-controlled trials including 3865 patients were included for analysis. In patients with HTPR, high-dose clopidogrel significantly reduced the risk of major adverse CV events or major adverse cardiac and cerebrovascular events [risk ratio (RR) 0.59; 95% confidence interval (CI) 0.39-0.88], stent thrombosis (RR 0.43; 95% CI 0.20-0.92), and target vessel revascularization (RR 0.31; 95% CI 0.10-0.93), without increasing major bleeding (RR 0.75; 95% CI 0.43-1.31) compared with standard-dose clopidogrel.

CONCLUSION

A high MD of clopidogrel may be a feasible and readily available treatment to lower the risk of recurrent CV events in patients with HTPR after undergoing percutaneous coronary intervention, especially in HTPR patients with coronary artery disease and chronic kidney disease.

Assessment of platelet-derived thrombogenicity with the total thrombus-formation analysis system in coronary artery disease patients receiving antiplatelet therapy

BACKGROUND

Accurate evaluation of thrombogenicity helps to prevent thrombosis and excessive bleeding. The total thrombus-formation analysis system (T-TAS) was developed for quantitative analysis of platelet thrombus formation by the use of microchips with thrombogenic surfaces (collagen, platelet chip [PL-chip]; collagen plus tissue factor, atherome chip [AR-chip]). We examined the utility of the T-TAS in the assessment of the efficacy of antiplatelet therapy in patients with coronary artery disease (CAD).

METHODS AND RESULTS

In this cross-sectional study, 372 consecutive patients admitted to the cardiovascular department were divided into three groups: patients not receiving any antiplatelet therapy (control, n = 56), patients receiving aspirin only (n = 69), and patients receiving aspirin and clopidogrel (n = 149). Blood samples were used for the T-TAS to measure the platelet thrombus-formation area under the curve (AUC) at various shear rates (1500 s(-1) [PL18 -AUC10 ] and 2000 s(-1) [PL24 -AUC10 ] for the PL-chip; 300 s(-1) [AR10 -AUC30 ] for the AR-chip). The on-clopidogrel platelet aggregation was measured by the use of P2Y12 reaction units (PRUs) with the VerifyNow system. The mean PL24 -AUC10 levels were 358 ± 111 (± standard deviation) (95% confidence interval [CI] 328.9-387.1) in the control group, 256 ± 108 (95% CI 230.5-281.5) in the aspirin group, and 113 ± 91 (95% CI 98.4-127.6) in the aspirin/clopidogrel group. In the aspirin/clopidogrel group, the PL24 -AUC10 was higher in poor metabolizers (PMs) with cytochrome P450 2C19(CYP2C19) polymorphisms (152 ± 112, 95% CI 103.4-200.6) than in the non-PM group (87 ± 74, 95% CI 73.8-100.2).

CONCLUSIONS

Our findings suggest that the PL24 -AUC10 level measured by the T-TAS is a potentially suitable index for the assessment of antiplatelet therapy in CAD patients.

Association of PON1, P2Y12 and COX1 with Recurrent Ischemic Events in Patients with Extracranial or Intracranial Stenting

BACKGROUND AND PURPOSE

Short-term combined use of clopidogrel and aspirin improves cerebrovascular outcomes in patients with symptomatic extracranial or intracranial stenosis. Antiplatelet non-responsiveness is related to recurrent ischemic events, but the culprit genetic variants responsible for the non-responsiveness have not been well studied. We aimed to identify the genetic variants associated with poor clinical outcomes.

METHODS

Patients with symptomatic extracranial or intracranial stenosis scheduled for stenting and receiving dual antiplatelets (clopidogrel 75 mg and aspirin 100 mg daily) for at least 5 days before intervention were enrolled. Ischemic events including recurrent transient ischemic attack, stroke, myocardial infarction, and vascular-related mortality within 12 months follow-up were recorded. We examined the influence of genetic polymorphisms on treatment outcome in our patients.

RESULTS

A total of 268 patients were enrolled into our study and ischemic events were observed in 39 patients. For rs662 of paraoxonase 1 (PON1), allele C was associated with an increased risk of ischemic events (OR = 1.64, 95%CI = 1.03-2.62, P = 0.029). The A-allele carriers of rs2046934 of P2Y12 had a significant association with adverse events (OR = 2.01, 95%CI = 1.10-3.67, P = 0.041). The variant T-allele of cyclooxygenase-1 (COX1) rs1330344 significantly increased the risk of recurrent clinical events (OR = 1.85, 95%CI = 1.12-3.03, P = 0.017). The other single nucleotide polymorphism (SNP) had no association with ischemic events.

CONCLUSIONS

PON1, P2Y12 and COX1 polymorphisms were associated with poorer vascular outcomes. Testing for these polymorphisms may be valuable in the identification of patients at risk for recurrent ischemic events.

Prevalence and risk factors of clopidogrel non-response among Saudi patients undergoing coronary angiography

OBJECTIVES

To estimate the prevalence of clopidogrel non-response and identify its risk factors among Saudi patients. 

METHODS

This cross-sectional study was conducted at Prince Sultan Cardiac Center, Riyadh, Kingdom of Saudi Arabia between January and June 2013, to assess the degree of platelet inhibition using the VerifyNow assay (Accumetrics, San Diego, CA, USA) after receiving clopidogrel standard loading dose. Clopidogrel resistance was defined as ≤15% platelet inhibition or greater than 213 P2Y12 reaction units (PRU). 

RESULTS

Three hundred and four patients were included in the study. The mean age was 60.3 ± 11.4 years, and 73% were males. Clopidogrel doses were 300 mg (57%), 600 mg (27%), and 75 mg (16%). All patients used aspirin (81 mg in 94%). Approximately 66% (200/304) showed in vitro clopidogrel non-response, 54% had low platelet inhibitions, and 61% had high post-loading PRU. Using multivariate regression analysis that included all significant characteristics; only diabetes (odds ratio [OR]: 2.36, 95% confidence interval [CI]: 1.30-4.27, p=0.005) and higher preloading PRU (OR: 2.39, 95% CI: 1.40-4.11, p=0.002) remained significantly associated with higher clopidogrel non-response while myocardial infarction (OR: 0.34, 95% CI: 0.15-0.81, p=0.014) remained significantly associated with lower clopidogrel non-response. The associations of morbid obesity and diuretics use with higher clopidogrel non-response were slightly attenuated.  

CONCLUSION

Our findings indicate a high rate of clopidogrel in-vitro non-response among Saudi patients undergoing coronary angiography.

Clinical efficacy and safety of cilostazol: a critical review of the literature

Cilostazol is a unique antiplatelet agent that has been commercially available for over two decades. As a phosphodiesterase III inhibitor, it reversibly inhibits platelet aggregation yet also possesses vasodilatory and antiproliferative properties. It has been widely studied in a variety of disease states, including peripheral arterial disease, cerebrovascular disease, and coronary artery disease with percutaneous coronary intervention. Overall, cilostazol appears to be a promising agent in the management of these disease states with a bleeding profile comparable to placebo; even when combined with other antiplatelet agents, cilostazol does not appear to increase the rate of bleeding. Despite the possible benefit of cilostazol, its use is limited by tolerability as some patients often report drug discontinuation due to headache, diarrhea, dizziness, or increased heart rate. To date, it has been predominantly studied in the Asian population, making it difficult to extrapolate these results to a more diverse patient population. This paper discusses the evolving role of cilostazol in the treatment of vascular diseases.

Cost-Effectiveness Analysis of Ticagrelor and Prasugrel for the Treatment of Acute Coronary Syndrome

BACKGROUND

In the management of Asian patients with acute coronary syndrome (ACS), the comparative cost-effectiveness of ticagrelor and prasugrel, referenced to generic clopidogrel, is unknown.

OBJECTIVE

To assess the cost-effectiveness of ticagrelor and prasugrel as compared with generic clopidogrel in patients with ACS in Singapore.

METHODS

A Markov model simulating a typical cohort of 62-year-old patients with ACS was constructed from a patient's perspective over a lifetime horizon. Treatment effects and adverse events, including nonfatal myocardial infarction, major bleeding related to non-coronary artery bypass grafting, dyspnea, or death, were estimated from pivotal trials comparing clopidogrel with ticagrelor and prasugrel, respectively. Costs were estimated from a tertiary hospital with more than 1500 admissions for ACS per year.

RESULTS

The incremental cost-effectiveness ratio (ICER) per life-year gained for ticagrelor was about three times more favorable than for prasugrel (Singapore dollar [SGD] 13,276 vs. SGD 38,809). The ICER per quality-adjusted life-year (QALY) for prasugrel and ticagrelor, however, was comparable at SGD 18,921 and SGD 18,647, respectively. Deterministic sensitivity analysis revealed that the ICER per QALY gained for prasugrel and ticagrelor was most sensitive to the hazard ratio of all-cause mortality and utility for dyspnea, respectively. Probabilistic sensitivity analysis demonstrated that compared with clopidogrel, the probabilities of prasugrel and ticagrelor being cost-effective are 87.1% and 88.3% based on the willingness-to-pay value of SGD 65,000 (one time the gross domestic product per capita in Singapore).

CONCLUSIONS

Ticagrelor is more cost-effective than prasugrel in reducing all-cause mortality in patients with ACS. The cost-effectiveness of ticagrelor and prasugrel become similar, however, when accounting for the impact of dyspnea on QALY.

P2Y12 antagonists in non-ST-segment elevation acute coronary syndromes: latest evidence and optimal use

Dual antiplatelet therapy (DAPT), which includes the combination of aspirin and a P2Y12 platelet receptor inhibitor, is a well-established antiplatelet regimen in the treatment of patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS). Three P2Y12 inhibitor options (clopidogrel, prasugrel and ticagrelor) are currently available, all having different efficacy and safety profiles along with contrasting contraindications, special warnings and precautions for use. This review compares and contrasts the unique P2Y12 antagonists in the NSTE-ACS setting, covering the latest evidence and their optimal use.

Omeprazole, pantoprazole, and CYP2C19 effects on clopidogrel pharmacokinetic-pharmacodynamic relationships in stable coronary artery disease patients

PURPOSE

Proton-pump Inhibitors use and CYP2C19 loss-of-function alleles are associated with reduced responsiveness to standard clopidogrel doses and increased cardiovascular events.

METHODS

Post-myocardial infarction patients heterozygous (wild type [wt]/*2, n = 41) or homozygous (*2/*2, n = 7) for the CYP2C19*2 genetic variant were matched with patients not carrying the variant (wt/wt, n = 58). All patients were randomized to a 300- or 900-mg clopidogrel loading dose. A PK/PD model was defined using the variation of the P2Y12 reaction unit relative to baseline.

RESULTS

Carriage of CYP2C19*2 allele and the use of omeprazole/esomeprazole were associated with the inter-individual variability in the active metabolite clearance. The relationship between inhibition of platelet aggregation (IPA, %) and the active metabolite AUC (h*μg/L) was described by a sigmoid function (Emax 56 ± 5%; EAUC50 15.9 ± 0.8 h*μg/L) with a gamma exponent (7.04 ± 2.26).

CONCLUSION

This on/off shape explains that a small variation of exposure may have a clinical relevance.

Stimulation of nitric oxide production contributes to the antiplatelet and antithrombotic effect of new peptide pENW (pGlu-Asn-Trp)

INTRODUCTION

New peptide pGlu-Asn-Trp (pENW), initially extracted from snake venom, significantly attenuates the formation of arterial and venous thrombi in vivo, and has modest in-vitro antiplatelet activity. This study was designed to investigate the underlying mechanisms.

METHODS

The rat carotid thrombosis model induced by FeCl3 was established to evaluate the antithrombotic activity of pENW. The effects of pENW on the production of nitric oxide (NO), as well as the expression and activity of endothelial nitric oxide synthase (eNOS), were determined. The vasorelaxant effect of pENW was evaluated using isolated rat aortic rings in the absence or presence of N(G)-nitro-L-arginine methyl ester (L-NAME, eNOS inhibitor). Furthermore, the in-vitro antiplatelet activity of pENW was investigated with the addition of sodium nitroprusside (SNP, NO donor) and/or L-NAME to further prove the role of NO and eNOS in the inhibitory effect of pENW on platelet aggregation.

RESULTS

In vivo, pENW inhibited thrombus formation induced by endothelial injury in a dose-dependent manner, with a significantly prolonged time to the occurrence of arterial occlusion. It was shown that pENW offered protection for blood vessels from oxidative injury. pENW significantly increased NO production in rats treated with pENW at 4 or 2mg/kg body weight. Furthermore, the production of NO from the cultured vascular endothelial cells was increased with the treatment of 10(-4)M and 10(-5)M pENW; pENW also enhanced eNOS expression and activity both in vivo and in vitro, and elicited a concentration-dependent vasorelaxation which was significantly inhibited by L-NAME. Notably, pENW inhibited ADP-induced platelet aggregation, and the inhibition was more significant in the presence of NO. The inhibition of platelet aggregation by pENW was significantly abolished by L-NAME.

CONCLUSIONS

The in-vivo antiplatelet and antithrombotic effects of pENW are at least partly mediated by the increased production of endogenous NO via up-regulation and stimulation of eNOS. The findings suggest that pENW could potentially be developed as a novel therapeutic agent in the treatment of platelet-driven disorders.

Platelets and diabetes mellitus

Platelet activation plays a key role in atherothrombosis in type 2 diabetes mellitus (T2DM) and increased in vivo platelet activation with enhanced thromboxane (TX) biosynthesis has been reported in patients with impairment of glucose metabolism even in the earlier stages of disease and in the preclinical phases. In this regards, platelets appear as addresses and players carrying and transducing metabolic derangement into vascular injury. The present review critically addresses key pathophysiological aspects including (i) hyperglycemia, glycemic variability and insulin resistance as determinants and predictors of platelet activation, (ii) inflammatory mediators derived from platelets, such as soluble CD40 ligand, soluble CD36, Dickkopf-1 and probably soluble receptor for advanced glycation-end-products (sRAGE), which expand the functional repertoire of platelets from players of hemostasis and thrombosis to powerful amplifiers of inflammation by promoting the release of cytokines and chemokines, cell activation, and cell-cell interactions; (iii) molecular mechanisms underpinning the less-than-expected antithrombotic protection by aspirin (ASA), despite regular antiplatelet prophylaxis at the standard dosing regimen, and (iv) stratification of patients deserving different antiplatelet strategies, based on the metabolic phenotype. Taken together, these pathophysiological aspects may contribute to the development of promising mechanism-based therapeutic strategies to reduce the progression of atherothrombosis in diabetic subjects.

CYP2C19 polymorphisms and coronary heart disease risk factors synergistically impact clopidogrel response variety after percutaneous coronary intervention

BACKGROUND

Platelet inhibition by clopidogrel is highly variable and the elevated platelet activity will increase the risk of major adverse cardiovascular events after percutaneous coronary intervention (PCI). CYP2C19 loss-of-function (LOF) alleles and risk factors of coronary heart disease (CAD) were reported to be associated with the low response of clopidogrel.

PURPOSE

This study was carried out to analyze the contributions of CYP2C19 polymorphisms and risk factors to the various clopidogrel responses in Chinese patients with stable CAD after PCI.

MATERIALS AND METHODS

The platelet reactivity index (PRI) was measured in 145 patients who underwent PCI using the vasodilator-stimulated phosphoprotein assay. Gene chip hybrid tests were used to analyze the genetic polymorphisms of CYP2C19.

RESULTS

With a cutoff value of 50% in PRI, 20.67% (31/145) of the patients were defined to be clopidogrel resistant. With respect to the normal *1, *2, and *3 LOF CYP2C19 alleles, patients were classified into three metabolism phenotypes: 39.31% were extensive, 47.59% were intermediate, and 13.10% were poor metabolizers (PMs). Of the enrolled patients, 53.82 and 9.66%, respectively, were carriers of *2 and *3 alleles. There was a significant difference in PRI between PM and either extensive or intermediate metabolizers (P<0.05). In all, 36.84% of the patients with the PM phenotype were clopidogrel resistant. Carriers of two CYP2C19 LOF alleles, BMI, and the presence of type 2 diabetes were three independent risk factors for clopidogrel resistance.

CONCLUSION

Genetic CYP2C19 polymorphisms and CAD risk factors - type 2 diabetes mellitus and BMI - synergistically affect the antiplatelet activity of clopidogrel and the occurrence of major adverse cardiovascular events after PCI.

Comparison of the effect of CYP2C19 polymorphism on clinical outcome between acute coronary syndrome and stable angina

AIM

CYP2C19 polymorphism modulates platelet reactivity in coronary artery disease patients with stent implants. However, the impact of the CYP2C19 genotype on clopidogrel response and clinical outcome has not been fully understood to date.

METHODS

We enrolled 518 consecutive patients with acute coronary syndrome (ACS) (n=214) and stable angina (SA) (n=304). All patients received stent implants followed by dual antiplatelet therapy of aspirin and clopidogrel. We determined CYP2C19 phenotype, measured platelet reactivity, and assessed the risk of cardiovascular events.

RESULTS

During a median follow-up of 894 days, the rate of cardiovascular events was higher in patients of the ACS group than the SA group (ACS: 20.1%, SA: 12.5%, p=0.015). The mean platelet reactivity was significantly higher in the CYP2C19 loss-of-function allele carriers of the two groups (ACS, non-carriers: 3909±1836AUmin, carriers: 4854±1594AUmin, respectively, p<0.01; SA, 3606±1579AUmin, 4381±1373AUmin, ±SD, p<0.01). In the ACS group, cardiovascular events were higher in the loss-of-function allele carriers (24.6%) versus non-carriers (11.1%, p<0.05), but no such difference was noted in the SA group (carriers: 14.8%; non-carriers: 7.9%, p=0.078). Furthermore, landmark analysis from 30 days did not show differences in ACS group (carriers: 14.8%, non-carriers: 11.1%, p=0.315). Multivariate Cox proportional hazards analysis identified the presence of loss-of-function allele as an independent predictor of cardiovascular events (hazard ratio, 2.1, 95% CI, 1.194-3.587, p=0.010).

CONCLUSIONS

The impact of CYP2C19 loss-of-function gene on clinical outcome is more powerful in early phase of ACS compared with SA.

High rates of prasugrel and ticagrelor non-responder in patients treated with therapeutic hypothermia after cardiac arrest

INTRODUCTION

After cardiac arrest due to acute coronary syndromes (ACS) therapeutic hypothermia (HT) is the standard care to reduce neurologic damage. Additionally, the concomitant medical treatment with aspirin and a P2Y12 receptor inhibitor like clopidogrel (Cl), prasugrel (Pr) or ticagrelor (Ti) is mandatory. The platelet inhibitory effect of these drugs under hypothermia remains unclear.

METHODS

164 patients with ACS were prospectively enrolled in this study. 84 patients were treated with HT, 80 patients were under normothermia (NT). All patients were treated with aspirin and one of the P2Y12 receptor inhibitors Cl, Pr or Ti. 24h after the initial loading dose the platelet reactivity index (PRI/VASP-index) was determined to achieve the platelet inhibitory effect.

RESULTS

In the HT-group the PRI/VASP-index was significantly higher compared to the NT-group (54.86%±25.1 vs. 28.98%±22.8; p<0.001). In patients under HT receiving Cl, the platelet inhibition was most markedly reduced (HT vs. NT: 66.39%±19.1 vs. 33.36%±22.1; p<0.001) compared to Pr (HT vs. NT: 37.6%±25.0 vs. 27.04%±25.5; p=0.143) and Ti (HT vs. NT: 41.5%±21.0 vs. 17.83%±14.5; p=0.009). The rate of non-responder defined as PRI/VASP-index>50% was increased in HT compared to NT (60.7% vs. 22.5%; p<0.001) with the highest rates in the group receiving Cl (CL: 82% vs. 26%, p<0.001; Pr: 32% vs. 23%; n.s.; Ti: 30% vs. 8%, n.s.).

CONCLUSION

The platelet inhibitory effect in patients treated with HT after cardiac arrest is significantly reduced. This effect was most marked with the use of Cl. The new P2Y12-inhibitors Pr and Ti improved platelet inhibition in HT, but could not completely prevent non-responsiveness.

[New antiplatelet drugs in coronary artery disease]

The dual antiplatelet therapy with acetylsalicylic acid and clopidogrel has been the mainstay of both acute and chronic phase coronary artery disease, reducing importantly the risk of adverse events. Despite a correct compliance, a non-negligible rate of adverse events still happens. New compounds, with improved properties, are now clinically available (such as prasugrel or ticagrelor) or under advanced development. The aim of the present review is the description of these new compounds, particularly prasugrel and ticagrelor.