The effect of ticagrelor versus clopidogrel on high on-treatment platelet reactivity: combined analysis of the ONSET/OFFSET and RESPOND studies

Role of ticagrelor in the peri-thrombolytic phase for patients with ST-segment elevation myocardial infarction: a comprehensive review

Recent years have seen ticagrelor, a potent P2Y12 inhibitor, emerge as a significant advancement in the peri-thrombolytic management of patients with ST-segment elevation myocardial infarction (STEMI), offering a promising alternative to traditional antiplatelet drugs like clopidogrel. This review critically examines the efficacy and safety of ticagrelor during the peri-thrombolytic phase in STEMI patients, drawing on evidence from key clinical trials such as TREAT and MIRTOS, as well as other relevant studies. These investigations underscore ticagrelor's superior platelet inhibition capabilities, which are crucial for minimizing thrombotic complications post-thrombolysis without increasing bleeding risks. Despite its potential, clopidogrel remains the guideline-recommended choice for such patients, leaving the appropriateness of ticagrelor in this context open to debate. By summarizing the current evidence and identifying gaps in our understanding, this study advocates for targeted research to clarify the long-term benefits and optimal deployment of ticagrelor, highlighting its evolving significance in cardiovascular care.

Switching Platelet P2Y12 Receptor Inhibiting Therapies

Antiplatelet therapy involving aspirin and a P2Y12 receptor inhibitor is fundamental in managing patients with atherothrombotic disease. Switching between P2Y12 inhibitors is frequently observed in clinical settings for various reasons, such as safety, efficacy, patient adherence, or cost concerns. Although it occurs often, the optimal method for switching remains a concern owing to potential drug interactions, which can result in either inadequate platelet inhibition and subsequent thrombotic events or low platelet reactivity and increased bleeding risks due to therapy overlap. This review offers practical guidance on switching P2Y12 inhibitors, drawing from pharmacodynamic and clinical data.

Clopidogrel resistance and its relevance: Current concepts

Clopidogrel is the most widely used P2Y12 receptor inhibitor (P2Y12i) as a part of dual antiplatelet therapy along with aspirin. Clopidogrel is a pro-drug and is metabolized to its active metabolite by the hepatic enzyme cytochrome P4502C19 (CYP2C19). This active metabolite is responsible for the antiplatelet action of clopidogrel. Recent studies have demonstrated that single nucleotide polymorphisms in the CYP2C19 gene, including CYP2C19*2,*3,*4, and *5 alleles, result in reduced production of the active metabolite of clopidogrel, and hence reduced inhibition of platelet aggregation. This in turn enhances the incidence of stent thrombosis and recurrent cardiovascular (CV) events. We report a case of coronary stent thrombosis due to clopidogrel resistance proven by CYP2C19 genotyping. We then review the literature on clopidogrel resistance and its impact on CV outcomes. Subsequently, we discuss the methods of diagnosis of resistance, evidence from clinical trials for tailoring clopidogrel therapy, the role of potent P2Y12 inhibitors, the current guidelines, and future directions.

Negative Impact of ST-Segment Elevation Myocardial Infarction and Morphine Dose on Ticagrelor Uptake and Pharmacodynamics: A Population PK/PD Analysis of Pooled Individual Participant Data

BACKGROUND

Ticagrelor is widely used in patients with stable and acute coronary artery disease. Understanding the factors that influence its pharmacokinetics (PK) and pharmacodynamics (PD) could improve therapeutic outcomes. We therefore performed a pooled population PK/PD analysis using individual patient data from two studies. We focused on the impact of morphine administration and ST-segment elevation myocardial infarction (STEMI) on the risk of high platelet reactivity (HPR) and dyspnea.

METHODS

A parent-metabolite population PK/PD model was developed based on data from 63 STEMI, 50 non-STEMI, and 25 chronic coronary syndrome (CCS) patients. Simulations were then run to evaluate the risk of non-response and adverse events associated with the identified variability factors.

RESULTS

The final PK model consisted of first-order absorption with transit compartments, distribution with two compartments for ticagrelor and one compartment for AR-C124910XX (active metabolite of ticagrelor), and linear elimination for both drugs. The final PK/PD model was an indirect turnover model with production inhibition. Morphine dose and STEMI, independently, had a significant negative effect on the absorption rate (reduction of log([Formula: see text]) by 0.21×morphine dose (mg) and by 2.37 in STEMI patients, both p < 0.001), and the presence of STEMI significantly impacted both efficacy and potency (both p < 0.001). The simulations run with the validated model showed a high rate of non-response in patients with those covariates (RR 1.19 for morphine, 4.11 for STEMI and 5.73 for morphine and STEMI, all three p < 0.001). By increasing ticagrelor dosage, the negative morphine effect was reversible in patients without STEMI and just limited in patients with STEMI.

CONCLUSION

The developed population PK/PD model confirmed the negative impact of morphine administration and presence of STEMI on ticagrelor PK and antiplatelet effect. Increasing ticagrelor doses seems effective in morphine users without STEMI, whereas the STEMI effect is not entirely reversible.

The impact of high on-treatment platelet reactivity and fibrinogen levels on ischemic events in patients with ST elevation myocardial infarction: a prospective observational study

BACKGROUND

After treatment, high residual platelet reactivity (HRPR) is considered as an essential risk factor for recurrent ischemic events.

AIM

To evaluate the impact of fibrinogen on HRPR after implantation of emergency drug-eluting stents (DES) in patients treated with aspirin and clopidogrel or ticagrelor due to ST-elevation myocardial infarction (STEMI) and to explore the predictive values of HRPR and fibrinogen for adverse ischemic events at 12 months.

METHOD

This single-center prospective observational study analyzed patients with STEMI who underwent primary percutaneous coronary intervention (PCI) with second-generation DES implantation from January 2017 to December 2018. Platelet reactivity was measured by thromboelastography (TEG) at 60-72 h after primary PCI. HRPR was defined as the adenosine diphosphate-induced maximum amplitude (MA_ADP) > 47 mm.

RESULTS

A total of 919 patients were analyzed, of which 512 (55.8%) received aspirin and clopidogrel and 406 (44.2%) received aspirin and ticagrelor. Elevated fibrinogen levels were associated with an increased prevalence of HRPR (P < 0.001). High fibrinogen (quartile IV, ≥ 410 mg/dL) was an independent risk factor for HRPR after multivariate regression (odds ratio 6.556, 95% confidence interval [CI]: 3.200-13.431, P < 0.001). When analyzed by Kaplan-Meier survival curves, the combination of high fibrinogen and HRPR was strongly predictive for ischemic major adverse cardiac events at 12 months compared to the group without HRPR and with low fibrinogen (hazard ratio 9.681, 95% CI: 4.467-20.98, log-rank P < 0.001). Similar results were confirmed in subgroups according to different dual antiplatelet therapies.

CONCLUSION

A combination of high fibrinogen and HRPR may identify recurrent adverse ischemic events over 12 months. Ticagrelor exhibited more potent platelet inhibition and a better prognosis than clopidogrel.

Treatment of acute upper gastrointestinal bleeding occurred after percutaneous coronary intervention for acute myocardial infarction in patients with acute renal impairment: a case report

Upper gastrointestinal (UGI) bleeding after percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) in ordinary patients is a common complication and poses a dilemma for clinical doctors to treat. In patients with renal impairment, that is more difficult and has rarely been reported. This case report involves an 82-year-old man who received regular hemodialysis and underwent PCI for acute inferior wall ST-segment elevation myocardial infarction. On the third day after PCI, the patient developed acute UGI bleeding, and gastroscopy confirmed that he had developed compound gastroduodenal ulcers (active stage) with hyperemia of the surrounding mucosa. After fasting, blood transfusion, acid inhibition, gastric protection and symptomatic support treatment, the patient’s UGI bleeding remained uncontrolled. Finally, upper gastrointestinal bleeding was stopped by empiric transcatheter arterial embolization (TAE). The patient’s condition was controlled through active treatment, and he was eventually discharged from the hospital. Bleeding complications after coronary stenting often present a dilemma, particularly in patients with renal impairment. Therefore, patients such as this should be thoroughly evaluated before any treatment. In the case of no obvious hemorrhagic spots found on endoscopic examination and failure of conservative medical treatment, empiric transcatheter arterial embolization TAE is a well-tolerated and effective treatment for UGI bleeding.

Vertebral artery dissection and associated ruptured intracranial pseudoaneurysm successfully treated with coil assisted flow diversion: A case report and review of the literature

Dissecting intracranial pseudoaneurysms (IPs) are associated with a high incidence of rupture and poor neurologic outcomes. Lesions in the posterior circulation are particularly malignant and pose even greater management challenges. Traditional management consists of microsurgical vessel sacrifice with or without bypass. Flow diversion (FD) in the setting of subarachnoid hemorrhage (SAH) represents a reconstructive treatment option and can be paired with coil embolization to promote more rapid thrombosis of the lesion. We report a case of a ruptured dissecting vertebral artery (VA) IP successfully acutely treated with coil-assisted FD. A 53-year-old male presented with a right V4 dissection spanning the origin of the posterior inferior cerebellar artery and associated ruptured V4 IP. The patient was treated with coil-assisted FD. Oral dual-antiplatelet therapy (DAPT) was initiated during the procedure, and intravenous tirofiban was used as a bridging agent. Immediate obliteration of the IP was achieved, with near-complete resolution of the dissection within 48 h. The patient made a complete recovery, and angiography at 6 weeks confirmed total IP obliteration, reconstruction of the VA, and a patent stent. The use of FD and DAPT in the setting of acute SAH remains controversial. We believe that coil-assisted FD in carefully selected patients offers significant advantages over traditional microsurgical and endovascular options. The risks posed by DAPT and potential for delayed thrombosis with FD can be effectively mitigated with planning and the development of protocols. We discuss the current literature in the context of our case and review the challenges associated with treating these often devastating lesions.

Intensified antiplatelet therapy in patients after percutaneous coronary intervention with high on-treatment platelet reactivity: the OPTImal Management of Antithrombotic Agents (OPTIMA)-2 Trial

High on-treatment platelet reactivity (HOPR) is associated with increased risk of cardiovascular events in patients undergoing percutaneous coronary intervention (PCI). We randomised post-PCI patients with HOPR after 5 days of standard dual antiplatelet therapy (DAPT) to intensified therapy with aspirin 100 mg once daily in combination with either clopidogrel 150 mg once daily, clopidogrel 75 mg once daily plus cilostazol 100 mg twice daily, ticagrelor 90 mg twice daily, or standard therapy with clopidogrel 75 mg once daily (STD) for 1 month, after which all patients were switched to standard DAPT for a further 11 months. The primary outcome was residual HOPR rate at 1 month. We screened 1724 patients with light transmission aggregation studies and randomised 434 with HOPR. At 1 month the proportion of patients with persistent HOPR was significantly lower in the intensified therapy groups compared with STD group. Compared to the group receiving STD therapy, those receiving intensified therapy had significantly lower rate of major adverse cardiovascular events (MACE) at both 1 month and 12 months with no significant increase in bleeding. In patients with post-PCI HOPR, 1 month of intensified antiplatelet therapy provides greater platelet inhibition and improves outcomes without increasing bleeding. Clinical Trial Registration URL: http://www.clinicaltrials.gov; Unique Identifier: NCT01955200.

Efficacy and safety of ticagrelor versus clopidogrel with different dosages in acute coronary syndrome patients with high GRACE and CRUSADE scores

Objective

To investigate the efficacy and safety of ticagrelor and different dosages of clopidogrel after acute coronary syndrome.

Methods

We compared different antiplatelet strategies for the prevention of cardiovascular events in 1939 patients admitted to the hospital with an acute coronary syndrome undergoing percutaneous coronary intervention (PCI).

Results

At 24 months, a survival analysis showed that ticagrelor and double-dose clopidogrel decreased the incidence of MACCE (a composite of all-cause death, myocardial infarction (MI), target vessel revascularization and stroke) (p < 0.001, p = 0.012, respectively). Although double-dose clopidogrel obviously increased the risk of major bleeding (p < 0.001), a similar result was not observed in the ticagrelor group (p = 0.398). These two stronger antiplatelet strategies also decreased the incidence of myocardial infarction (p = 0.004 and 0.045, respectively). The advantages of ticagrelor are also evident in the endpoints of all cause death and target vessel revascularization. The NACCE (a composite of all-cause death, MI, stroke and major bleeding) rate was also reduced in the ticagrelor group (p = 0.004).

Conclusions

In PCI patients with a high ischemic and bleeding risk, the ticagrelor antiplatelet strategy significantly reduced the MACCE rate without increasing the risk of major bleeding. A decreased MACCE rate was also observed in patients administered the double dosage of clopidogrel, but the bleeding risk was increased compared with the control group.

TicagRelor Or Clopidogrel in severe or terminal chronic kidney patients Undergoing PERcutaneous coronary intervention for acute coronary syndrome: The TROUPER trial

Chronic kidney disease (CKD) is associated with an increased risk of acute coronary syndrome (ACS) and cardiovascular death. CKD patients suffering from ACS are exposed to an increased risk of thrombotic recurrences and a higher bleeding rate than patients with normal renal function. However, CKD patients are excluded or underrepresented in clinical trials. Therefore, determining the optimal antiplatelet strategy in this population is of utmost importance. We designed the TicagRelor Or Clopidogrel in severe or terminal chronic kidney patients Undergoing PERcutaneous coronary intervention for acute coronary syndrome (TROUPER) trial: a prospective, controlled, multicenter, randomized trial to investigate the optimal P2Y12 antagonist in CKD patients with ACS. Patients with stage ≥3b CKD are eligible if the diagnosis of ACS is made and invasive strategy scheduled. Patients are randomized 1:1 between a control group with a 600-mg loading dose of clopidogrel followed by a 75-mg/d maintenance dose for 1 year and an experimental group with a 180-mg loading dose of ticagrelor followed by a 90-mg twice daily maintenance dose for the same duration. The primary end point is defined by the rate of major adverse cardiovascular events, including death, myocardial infarction, urgent revascularization, and stroke at 1 year. Safety will be evaluated by the bleeding rate (Bleeding Academic Research Consortium). To demonstrate the superiority of ticagrelor on major adverse cardiovascular events, we calculated that 508 patients are required. The aim of the TROUPER trial is to compare the efficacy of ticagrelor and clopidogrel in stage >3b CKD patients presenting with ACS and scheduled for an invasive strategy. RCT# NCT03357874.

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).

Effect of Ticagrelor, a Cytochrome P450 3A4 Inhibitor, on the Pharmacokinetics of Tadalafil in Rats

Tadalafil is a cytochrome P450 (CYP) 3A4 substrate. Because there are few data on drug-drug interactions, it is advisable to take sufficient consideration when co-administering tadalafil with CYP3A4 inducers or inhibitors. This study was conducted to assess the effect of ticagrelor, a CYP3A4 inhibitor, on the pharmacokinetic properties of tadalafil after oral administration to rats. A total of 20 Sprague–Dawley male rats were randomly divided into the non-pretreated group and ticagrelor-pretreated group, and tadalafil was orally administered to each group after pretreatment with or without ticagrelor. Blood samples were collected at predetermined time points after oral administration of tadalafil. As a result, systemic exposure of tadalafil in the ticagrelor-pretreated group was significantly increased compared to the non-pretreated group (1.61-fold), and the clearance of tadalafil in the ticagrelor-pretreated group was significantly reduced than the non-pretreated group (37%). The prediction of the drug profile through the one-compartment model could explain the differences of pharmacokinetic properties of tadalafil in the non-pretreated and ticagrelor-pretreated groups. This study suggests that ticagrelor reduces a CYP3A-mediated tadalafil metabolism and that tadalafil and a combination regimen with tadalafil and ticagrelor requires dose control and specific pharmacotherapy.

Role of CYP2C19 alleles in the management of recurrent ischemic stroke

Purpose of review

CYP2C19 is the primary enzyme involved in the activation of clopidogrel, an antiplatelet agent used for secondary stroke prevention. An individual's CYP2C19 alleles are used to understand their CYP2C19-clopidogrel metabolizer phenotype. Single nucleotide polymorphisms of the CYP2C19 gene result in altered metabolism of this prodrug.

Recent findings

Three ischemic stroke cases were treated with clopidogrel. Despite confirming adequate drug exposure, medication adherence, and ruling out drug-drug interactions, all had recurrent ischemic stroke. Each case had a CYP2C19 *2/*17 genotype, categorizing them as intermediate clopidogrel metabolizers. Even with the gain-of-function allele, the loss-of-function allele resulted in lack of prodrug activation, leading to decreased efficacy in platelet inhibition.

Summary

These cases illustrate the importance of a thoughtful approach to secondary stroke prevention and demonstrate the utility of pharmacogenomic testing in clopidogrel hyporesponders. Recognition of the importance of CYP2C19 genotyping has the potential to enable better selection of appropriate secondary prevention strategies.

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.

Switching P2Y12 Receptor Inhibiting Therapies

Antiplatelet therapy with aspirin and a P2Y₁₂ receptor inhibitor is the cornerstone of treatment of patients with atherothrombotic disease manifestations. Switching between P2Y₁₂ inhibitors occurs commonly in clinical practice for a variety of reasons, including safety, efficacy, adherence, and economic considerations. There are concerns about the optimal approach for switching because of potential drug interactions, which may lead to ineffective platelet inhibition and thrombotic complications, or potential overdosing due to overlap in drug therapy, which might cause excessive platelet inhibition and increased bleeding. This review provides practical considerations of switching based on pharmacodynamic and clinical data available from the literature.

No Differences in Levels of Circulating Progenitor Endothelial Cells or Circulating Endothelial Cells Among Patients Treated With Ticagrelor Compared With Clopidogrel During Non- ST -Segment-Elevation Myocardial Infarction

Background

Ticagrelor use during acute coronary syndromes demonstrated a decrease in all‐cause mortality in the PLATO (Platelet Inhibition and Patient Outcomes) trial. This effect has been attributed to a non–platelet‐derived improvement in endothelial function. The aim of this study was to determine differences in the number of endothelial progenitor cells and/or circulating endothelial cells found in peripheral blood in patients treated with either ticagrelor or clopidogrel during non–ST‐segment–elevation myocardial infarction.

Methods and Results

In this multicenter, randomized study (NCT02244710), patients were considered for inclusion after non–ST‐segment–elevation myocardial infarction whenever they were P2Y₁₂‐inhibitor naïve. Ticagrelor and clopidogrel were allocated at a 1:1 ratio. Blood samples for determining endothelial progenitor cells and circulating endothelial cells were extracted before the antiplatelet loading dose, 48 hours after presentation of index symptoms, and 1 month after the event. A multichannel cytometer was used for optimal cell characterization. A total of 96 patients fulfilled the inclusion criteria. Circulating endothelial cell levels corrected by white blood cells were as follows at baseline, 48 hours, and 1 month: 44 (28–64), 50 (33–63), and 38 (23–62) cells/mL, respectively, for clopidogrel and 38 (29–60), 45 (32–85), and 35 (24–71) cells/mL, respectively, for ticagrelor (P=0.6). Endothelial progenitor cell levels were 29 (15–47), 27 (15–33), and 18 (10–25) cells/mL, respectively, for clopidogrel and 20 (11–33), 22 (12–32), and 18 (11–29) cells/mL, respectively, for ticagrelor (P=0.9). No differences in intraindividual changes were found.

Conclusions

Patients treated with ticagrelor during non–ST‐segment–elevation myocardial infarction, in comparison to clopidogrel, showed similar levels of endothelial progenitor cells and circulating endothelial cells. These data suggest that the endothelial protective effect mediated by ticagrelor is not related to bone marrow physiology modulation.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02244710.

Contemporary antiplatelet therapy in acute coronary syndromes: are there differences in outcomes and discontinuation between clopidogrel and ticagrelor?

BACKGROUND/AIM

We studied clinical outcomes and discontinuation rates in a 'real-world' population presenting with myocardial infarction treated with ticagrelor or clopidogrel.

METHODS

Between January 2012 and May 2015, 992 patients with acute myocardial infarction undergoing invasive management and adequately pre-treated with dual antiplatelet therapy were prospectively enrolled. Platelet aggregation was measured using the Multiplate analyser. Baseline characteristics, in-hospital outcomes and 1-year outcomes were collected.

RESULTS

Patients treated with ticagrelor were younger and less likely to be diabetic, have a previous myocardial infarction or present with a ST-elevation myocardial infarction (all P < 0.05). Those treated with ticagrelor also had lower CRUSADE (Can Rapid risk stratification of Unstable angina patients Suppress ADverse outcomes with Early implementation of the ACC/AHA guidelines; 20 ± 9.4 vs 23 ± 10.1, P < 0.0001) and GRACE (119 ± 28 vs 126 ± 32, P = 0.002) scores. High platelet reactivity was greatly reduced with ticagrelor compared to clopidogrel (16.1% vs 37.0%, respectively; P < 0.0001). Non-coronary artery bypass grafting-related thrombolysis in myocardial infarction major and minor bleeding occurred at similar rates in those treated with ticagrelor and clopidogrel. Rates of drug discontinuation in those treated with ticagrelor and clopidogrel were similar in hospital (20.2% vs 16.2%, P = 0.18) and between discharge and 1 year (29.9% vs 27.9%, P = 0.63). However, discontinuation due to dyspnoea, (3.3% vs 0%, P < 0.0001) and discontinuation due to any possible drug-related adverse event (9.3% vs 2.2%, P = 0.0001) was more common in those treated with ticagrelor compared to clopidogrel CONCLUSION: Ticagrelor is paradoxically being used in lower-risk patients rather than those most likely to benefit. Ticagrelor was associated with similar rates of bleeding but higher discontinuation rates due to adverse effects compared to clopidogrel.

Platelet reactivity in patients with acute coronary syndrome treated with prasugrel or ticagrelor in comparison to clopidogrel: a retrospective pharmacodynamic analysis

Dual antiplatelet therapy (DAPT) with aspirin and a P2Y₁₂ inhibitor is a mainstay of the prevention of stent thrombosis following percutaneous coronary intervention (PCI). In the 2015 European guidelines for the management of acute coronary syndrome (ACS), prasugrel (PRA) and ticagrelor (TICA) combined with aspirin are recommended as first-line therapy. Clopidogrel (CLO) is recommended as an alternative medication for patients with contradictions to these new drugs. This single-center study analyzed the platelet function of 809 ACS patients undergoing PCI and treatment with DAPT. The platelet response to ADP was determined using Multiplate® analyzer at a median of 3 days after PCI in 254 patients treated with PRA (loading dose [LD] 60 mg, 10 mg qd), 162 patients receiving TICA (LD 180 mg, D 90 mg bid), and 393 CLO-treated patients (LD 600 mg, 75 mg qd). An aggregation >468 arbitrary units (AU)*min was defined as "high on-treatment platelet reactivity" (HPR), <188 AU*min as "low on-treatment platelet reactivity" (LPR). Platelet response in PRA-treated patients was lower compared to CLO or TICA (median; interquartile range: PRA 220 [163-275] AU*min vs. CLO 268 [186-387] AU*min, p < 0.001 vs. TICA 245 [190-320] AU*min, p = 0.001). Only 1.6% of PRA patients were stratified as HPR and 34.6% as LPR, while in the TICA group 1.9% fulfilled the criteria of HPR and 24.1% criteria of LPR. Sixteen percent of CLO patients were stratified as HPR and 26.2% as LPR. In a real-world cohort of ACS patients following PCI, PRA results in more potent inhibition of platelet function compared to CLO and TICA. TICA achieves a consistent antiplatelet effect with reduced rates of HPR and LPR in relation to CLO.

Ticagrelor vs prasugrel one-month maintenance therapy: Impact on platelet reactivity and bleeding events

Platelet reactivity (PR) and bleeding events following therapy with ticagrelor vs prasugrel have not been adequately studied. We aimed to compare PR and bleeding events in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) while on ticagrelor vs prasugrel for one month. Consecutive patients who were discharged either on ticagrelor 90 mg bid maintenance dose (MD) or prasugrel 10 mg MD were invited for PR assessment (VerifyNow, in PRU) at one month. High PR (HPR) was defined as >208 PRU. Bleeding events [Bleeding Academic Research Consortium (BARC) classification] were monitored. Out of 937 screened patients, 512 were analysed, 278 under ticagrelor MD and 234 under prasugrel MD. PR at 30 days (C-statistic of the propensity score model 0.63, 0.58–0.67 95% CI, p<0.001) was lower when on ticagrelor compared with prasugrel (33.3, 95% CI 29.3–37.3 vs 84.6, 95% CI 73.6–95.6, p<0.001). In the analysed population more BARC type 1 bleeding events were observed with ticagrelor compared to prasugrel (36.7% vs 28.2%, p=0.047). In 221 propensity score matched pairs, BARC type 1 bleeding rate was marginally higher in ticagrelor vs prasugrel treated patients (35.7% vs 27.1%, p=0.05). BARC type ≥2 events did not differ between groups 5 (2.3%) vs 5 (2.3%). HPR rate was higher for prasugrel-treated patients (5.4% vs 0%, p<0.001). In conclusion, in patients with ACS undergoing PCI, ticagrelor MD produces a significantly higher platelet inhibition compared to prasugrel MD. This pharmacodynamic difference might be associated with more nuisance bleeding events with ticagrelor use.

Clinical Trial Registration ClinicalTrials.gov Identifier: NCT01774955.

Parathyroid Hormone Levels and High-Residual Platelet Reactivity in Patients Receiving Dual Antiplatelet Therapy With Acetylsalicylic Acid and Clopidogrel or Ticagrelor

BACKGROUND

High-residual-on-treatment platelet reactivity still represents a challenging issue, potentially vanishing the benefits of dual antiplatelet treatment in patients with coronary artery disease. However, very few is known on the determinants of suboptimal response to antiplatelet agents. Recent interests have emerged on the potential prothrombotic effect of parathyroid hormone (PTH). Therefore, the aim of the present study was to assess the impact of parathyroid hormone (PTH) on platelet reactivity in patients receiving DAPT after an acute coronary syndrome or PCI.

METHODS

Patients treated with DAPT (ASA and clopidogrel or ticagrelor) were scheduled for platelet function assessment at 30- to 90-days postdischarge. By whole blood impedance aggregometry, HRPR was considered for ASPI test >862 AU*min (for ASA) and ADP test values ≥417 AU*min (for ADP antagonists).

RESULTS

We included 362 patients on DAPT, 125 (34.5%) receiving clopidogrel, and 237 (65.5%) on ticagrelor. Patients were divided according to PTH quartiles values (<45.8; 45.8-60.3; 60.4-88; ≥88.1 pg/mL). Higher PTH was associated with older age (P = 0.001); renal failure (P < 0.001), higher HDL cholesterol (P = 0.006) and creatinine (P < 0.001) and lower 25-OH cholecalciferol (P < 0.001). Suboptimal response to ASA was infrequent (2.8%), and not influenced by the levels of PTH (P = 0.57). ADP-mediated platelet aggregation was significantly increased in patients with higher PTH (P = 0.03), with an absolute increase in the prevalence of HRPR to ADP antagonists for higher PTH (24.7% vs. 40%, P = 0.007 for 4th vs. 1-3rd quartiles, adjusted OR[95%CI] = 2.04[1.14-3.64], P = 0.02). By the use of the ROC curve, we identified PTH levels above 96.7 pg/mL as the best predictor of HRPR with ADP antagonists (adjusted OR[95%CI] = 2.52[1.31-4.87], P = 0.006). Higher rate of HRPR was confirmed for PTH >96.7 pg/mL among the subgroup of patients on clopidogrel (51.5 vs. 85.7%, P = 0.001; adjusted OR[95%CI] = 12.5[2.6-60.9], P = 0.002), but not among ticagrelor-treated patients (11.3 vs. 16.7%, P = 0.31; adjusted OR[95%CI] = 1.55[0.56-4.6], P = 0.42).

CONCLUSION

In patients receiving dual antiplatelet therapy for coronary artery disease, higher PTH levels are associated with an increased ADP-mediated platelet reactivity and suboptimal response to clopidogrel, especially for values above 96.7 pg/mL, while not influencing the effectiveness of ASA and ticagrelor.

Impact of oral P2Y12 inhibitors on residual thrombus burden and reperfusion indexes in patients with ST-segment elevation myocardial infarction

AIMS

We sought to assess the impact of different oral P2Y12 receptor inhibitors on residual thrombus and reperfusion indexes in ST-segment elevation myocardial infarction patients enrolled in the COCTAIL II trial, which included 128 primary percutaneous coronary interventions randomized to intracoronary vs. intralesion abciximab bolus with or without thrombectomy.

METHODS

Patients were divided into three groups: clopidogrel (n = 44), prasugrel (n = 45) and ticagrelor (n = 39). Residual intra-stent thrombus was quantified by optical coherence tomography using both the number of cross-sections with thrombus area more than 10% and thrombus volume. Reperfusion indexes included thrombolysis in myocardial infarction (TIMI) flow, corrected TIMI frame count, myocardial blush grade (MBG) and complete ST-segment resolution (≥70%).

RESULTS

In the prasugrel group, optical coherence tomography depicted a lower percentage of cross-sections with residual thrombus area more than 10% [4.0 (1.0-8.5)], as compared with clopidogrel [8.0 (1.0-15.0), P = 0.011] and ticagrelor [7.0 (3.0-13.5), P = 0.026].A higher thrombus volume was found in the clopidogrel group 4.0 mm(2.7-6.2) as compared with the prasugrel group [2.8 mm(1.8-4.4), P = 0.023], whereas the other between-group comparisons yield no significant differences. The frequency of MBG 3 was higher in the prasugrel group (73.3%) as compared with clopidogrel (45.5%) and ticagrelor [(56.4%), P = 0.027]. Final TIMI flow, TIMI frame count and ST resolution were not significantly different across the three groups (P = 0.423, 0.179 and 0.848, respectively). At multivariate analysis, pretreatment with prasugrel was independently associated with MBG 3 (odds ratio = 3.93; 95% confidence interval = 1.01-15.39).

CONCLUSION

Prasugrel loading dose was associated with a lower percentage of cross-sections with residual thrombus area more than 10% as compared with both clopidogrel and ticagrelor, although intrastent thrombus volume was not significantly different between prasugrel and ticagrelor.The frequency of MBG 3 was the only reperfusion index that was significantly more prevalent in prasugrel treated group as compared with clopidogrel and ticagrelor groups.

Morphine decreases ticagrelor concentrations but not its antiplatelet effects: a randomized trial in healthy volunteers

BACKGROUND

Our recent drug interaction trial with clopidogrel shows that morphine decreases the concentrations and pharmacodynamic effects of clopidogrel, which could lead to treatment failure in susceptible individuals. We hypothesized that the pharmacodynamic consequences of drug-drug interactions would be less between morphine and ticagrelor.

MATERIALS AND METHODS

Twenty-four healthy subjects received a loading dose of 180 mg ticagrelor together with placebo or 5 mg morphine intravenously in a randomized, double-blind, placebo-controlled, crossover trial. Pharmacokinetics were determined by liquid chromatography tandem mass spectrometry, and ticagrelor pharmacodynamic effects were measured by platelet function tests (whole blood platelet aggregation: multiplate, platelet plug formation: PFA-100, vasodilator-stimulated phosphoprotein (VASP) phosphorylation assay).

RESULTS

Concomitant i.v. injection of morphine slows drug resorption of ticagrelor and its active metabolite (P < 0·05) by 1 h and decreases plasma levels of ticagrelor and its active metabolite by 25-31% (P ≤ 0·03) and the drug exposure (area under the curve) by 22-23% (P ≤ 0·01). Importantly, however, the pharmacodynamic effects of ticagrelor on platelet aggregation in whole blood, platelet plug formation and VASP phosphorylation are not affected by morphine.

CONCLUSIONS

Morphine co-administration moderately decreases ticagrelor plasma concentrations but does not inhibit its pharmacodynamic effects in healthy volunteers within 6 h after drug administration. Limitations of our trial include the investigation in healthy volunteers under standardized conditions, which does not necessarily reflect a realistic emergency scenario.

Ticagrelor overcomes high platelet reactivity in patients with acute myocardial infarction or coronary artery in-stent restenosis: a randomized controlled trial

High on-treatment platelet reactivity (HTPR) is accompanied by an increased risk of adverse outcomes. Direct comparison of the antiplatelet effects between ticagrelor and high-dose clopidogrel has not yet been reported in acute myocardial infarction (AMI) or coronary artery in-stent restenosis (ISR) patients with HTPR. Consecutive patients with AMI or coronary artery ISR treated with standard-dose clopidogrel (75 mg/day) were screened with the VerifyNow assay, defining HTPR as P2Y12 reaction units (PRUs)>208. Of the 102 screened patients, 48 (47.06%) patients with HTPR were randomly assigned to either ticagrelor (180 mg/90 mg twice daily) or high-dose clopidogrel (150 mg/day) for 24 hours. Baseline characteristics and mean PRUs were similar in both groups. After 24 hours, ticagrelor was associated with a significantly lower platelet reactivity than high-dose clopidogrel (44.38±40.26  vs. 212.58±52.34 PRU, P<0.05). No patient receiving ticagrelor exhibited HTPR, whereas 15 (62.50%) patients after treatment with high-dose clopidogrel remained HTPR (P<0.05). During the follow-up (mean, 138.42±53.59 days), no patient exhibited a major bleeding event in either treatment group. In conclusion, in patients with AMI or coronary artery ISR exhibiting HTPR after standard clopidogrel treatment, ticagrelor is significantly more effective compared with high-dose clopidogrel in overcoming HTPR.

A comparative pharmacodynamic study of ticagrelor versus clopidogrel and ticagrelor in patients undergoing primary percutaneous coronary intervention: the CAPITAL RELOAD study

Background

In patients undergoing primary percutaneous coronary intervention (PPCI) ticagrelor is superior to clopidogrel in reducing cardiovascular events. This study sought to evaluate the effect of clopidogrel pretreatment on the pharmacodynamics of ticagrelor in patients undergoing PPCI.

Methods

We measured platelet reactivity using the VerifyNow P2Y12 assay at baseline, 1, 2, 4, 6, 12, 24, and 48 hours following ticagrelor bolus in patients previously loaded with clopidogrel (C+T) and in thienopyridine-naive patients (T) referred to our centre for PPCI.

Results

In total, 52 consecutive eligible patients with ST-elevation myocardial infarction (STEMI) were enrolled (27 C+T and 25 T). Baseline characteristics and mean baseline platelet reactivity units (PRUs) were similar between the groups. The primary endpoint, the proportion of patients achieving a PRU<208 at 2 hours, was more frequently achieved in the C+T group compared to T treatment (76.0% vs 44.4%, p = 0.026). Notably, C+T therapy resulted in fewer patients with high platelet reactivity at 1 hour (56.0% vs. 14.8%), 4 hours (100.0% vs. 61.5%) and 6 hours (100.0% vs. 64%, p<0.01 for all comparisons). Furthermore, C+T therapy was associated with lower PRU values from 2 to 48 hours.

Conclusions

In patients referred for PPCI, ticagrelor bolus following clopidogrel resulted in more rapid and profound platelet inhibition, demonstrating a positive pharmacodynamic interaction. Further study is needed to determine if this pharmacodynamic effect translates into reduced clinical events.

Assessing post-treatment platelet reactivity: a focus on patient selection and setting

Dual antiplatelet therapy is critical to inhibit platelet reactivity in order to prevent ischemic recurrences in stented patients. However, studies have observed a variable blockade of the P2Y12 adenosine diphosphate receptor between patients following clopidogrel intake. This interindividual variability in the biological response is not uncommon with clopidogrel (about 50%) and even prasugrel (20%). High on-treatment platelet reactivity (HTPR) is correlated with thrombotic events following percutaneous coronary intervention. Several studies suggested that tailoring of antiplatelet therapy based on platelet reactivity (PR) monitoring could safely reduce the rate of major adverse cardiovascular events in HTPR patients. In addition, low on-treatment PR was recently associated with bleeding events both in patients treated with prasugrel and clopidogrel. Of importance, bleedings are associated with a poor prognosis in stented patients. Overall, the potential of PR monitoring to individualize antiplatelet therapy might benefit stented patients by reducing both ischemic and bleeding risks. However, such strategies remain to be evaluated in adequately designed large-scale randomized clinical trials.

Platelet reactivity tests for assessing antiplatelet drug response: what the clinician needs to know

Antiplatelet therapy is a cornerstone in the treatment of cardiovascular disease to prevent ischemic events. Various tests have become clinically available to measure platelet function after antiplatelet treatment. A wide interpatient variability in the magnitude of platelet inhibition has been demonstrated in numerous studies, especially in response to clopidogrel. Several reasons including clinical, pharmacological and genetic factors have been identified. High on-clopidogrel platelet reactivity has been linked to adverse clinical outcome, in particular to stent thrombosis after percutaneous coronary interventions. New antiplatelet drugs including prasugrel and ticagrelor have been advocated to overcome the limitations of clopidogrel. Several studies addressed the concept of tailored antiplatelet treatment according to the results of platelet function testing. Within this review, we summarize the current status of personalized antiplatelet therapy for cardiovascular disease.

Thienopyridine efficacy and cigarette smoking status

Dual antiplatelet therapy with aspirin and a P2Y12 receptor blocker is an established regimen to reduce the risk of ischemic event occurrence in patients with high-risk cardiovascular (CV) disease. Cigarette smoking is an important cardiovascular risk factor. However, several investigators have reported what may be termed a "new" "smoker's paradox", whereby clopidogrel-treated nonsmokers appear to have either less or no CV-event reduction when compared to the substantial CV-event reduction in clopidogrel-treated smokers based on several large-scale trials. This "smoker's paradox" observed in multiple clinical outcome studies is also supported by emerging "real-world" data that also suggest clopidogrel nonsmokers do not fare as well as smokers treated with clopidogrel. In support of the new "smoker's paradox", pharmacodynamic studies have also shown that smoking status influences clopidogrel responsiveness in healthy volunteers, acute coronary syndrome patients, and patients treated with percutaneous coronary intervention. Finally, there is a substantial, albeit not entirely consistent, body of pharmacodynamic and clinical outcome data supporting a reduced antiplatelet effect of clopidogrel in non-smokers as compared to smokers. The clinical relevance of this interaction has never been demonstrated in a prospective trial. The focus of this review is to critically evaluate the reported interaction between cigarette smoking status and thienopyridine efficacy.

Clopidogrel pretreatment in primary percutaneous coronary intervention: prevalence of high on-treatment platelet reactivity and impact on preprocedural patency of the infarct-related artery

To date, there is limited data on levels of platelet inhibition achieved in patients with ST-elevation myocardial infarction (STEMI) who are loaded with clopidogrel and aspirin (ASA) prior to undergoing primary percutaneous coronary intervention (P-PCI). The aim of this investigation was to evaluate the percentage of STEMI patients with high on-treatment platelet reactivity (HPR) to clopidogrel at the time of initiating P-PCI and its association with the initial patency of the infarct-related artery (IRA). This prospective pharmacodynamic study included 50 STEMI patients, previously naïve to oral antiplatelet agents, who received 500-mg ASA and 600-mg clopidogrel loading doses prior to P-PCI. Platelet function assessment was performed at the beginning of the procedure using various assays, including VerifyNow™ system (primary endpoint), light transmission aggregometry and multiple electrode aggregometry. The percentage of patients with suboptimal response to clopidogrel and ASA assessed with the VerifyNow™ system was 88.0% and 28.6%, respectively. Similar results were obtained with the other assays used. A higher percentage of patients with initial patency of the IRA was observed among those patients without HPR compared with those with HPR to clopidogrel (66.7% vs 15.9%; p=0.013), while no differences were observed regarding postprocedural angiographic or electrocardiographic outcomes. In conclusion, this study shows that a high percentage of STEMI patients have inadequate levels of clopidogrel-induced and, to a lesser extent, aspirin-mediated platelet inhibition when starting a P-PCI procedure, and suggests that a poor response to clopidogrel might be associated with impaired initial TIMI flow in the IRA.

Comparison of prasugrel and ticagrelor loading doses in ST-segment elevation myocardial infarction patients: RAPID (Rapid Activity of Platelet Inhibitor Drugs) primary PCI study

OBJECTIVES

This study sought to compare the action of prasugrel and ticagrelor in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PPCI).

BACKGROUND

It has been documented that prasugrel and ticagrelor are able to provide effective platelet inhibition 2 h after a loading dose (LD). However, the pharmacodynamic measurements after prasugrel and ticagrelor LD have been provided by assessing only healthy volunteers or subjects with stable coronary artery disease.

METHODS

Fifty patients with STEMI undergoing PPCI with bivalirudin monotherapy were randomized to receive 60 mg prasugrel LD (n = 25) or 180 mg ticagrelor LD (n = 25). Residual platelet reactivity was assessed by VerifyNow at baseline and 2, 4, 8, and 12 h after LD.

RESULTS

Platelet reactivity units (PRU) 2 h after the LD (study primary endpoint) were 217 (12 to 279) and 275 (88 to 305) in the prasugrel and ticagrelor groups, respectively (p = NS), satisfying pre-specified noninferiority criteria. High residual platelet reactivity (HRPR) (PRU ≥240) was found in 44% and 60% of patients (p = 0.258) at 2 h. The mean time to achieve a PRU <240 was 3 ± 2 h and 5 ± 4 h in the prasugrel and ticagrelor groups, respectively. The independent predictors of HRPR at 2 h were morphine use (odds ratio: 5.29; 95% confidence interval: 1.44 to 19.49; p = 0.012) and baseline PRU value (odds ratio: 1.014; 95% confidence interval: 1.00 to 1.03; p = 0.046).

CONCLUSIONS

In patients with STEMI, prasugrel showed to be noninferior as compared with ticagrelor in terms of residual platelet reactivity 2 h after the LD. The 2 drugs provide an effective platelet inhibition 2 h after the LD in only a half of patients, and at least 4 h are required to achieve an effective platelet inhibition in the majority of patients. Morphine use is associated with a delayed activity of these agents. (Rapid Activity of Platelet Inhibitor Drugs Study, NCT01510171).

Current evidence for monitoring platelet reactivity in acute coronary syndrome: a plea for individualized antiplatelet treatment

Although clopidogrel is more effective in preventing thrombotic complications than aspirin alone in a broad spectrum of patients with ischemic heart disease, many of its limitations were recently brought to light including a delayed onset of action and highly unpredictable P2Y12-receptor inhibition. New-generation ADP-receptor antagonists, such as prasugrel and ticagrelor, were designed and developed to overcome these limitations, providing a more rapid, more reliable and more potent P2Y12-receptor inhibition. These pharmacodynamic benefits of new-generation antiplatelet agents were translated into significant clinical advantage among patients with acute coronary syndrome (ACS), especially in preventing stent thrombosis. However, the downsides of the unselected use of novel P2Y12-receptor antagonists include higher risk of bleeding and increased costs. Platelet reactivity testing might become a useful tool to help balance between bleeding and thrombosis with P2Y12-receptor antagonists; however, its role in clinical practice for patients undergoing percutaneous coronary intervention (PCI) remains uncertain. The aim of this viewpoint article is to summarize the currently available evidence supporting a role of platelet function testing in patients with ACS after PCI.

Ticagrelor: the first novel reversible P2Y(12) inhibitor

INTRODUCTION

Dual antiplatelet therapy is a standard of care for treating patients with acute coronary syndrome (ACS). Combination therapy with aspirin and one of the P2Y(12) inhibitors (clopidogrel, prasugrel, or most recently, ticagrelor ) has been recommended by both ACC/AHA and ESC guidelines for ACS patients.

AREAS COVERED

Ticagrelor is the first generation of a new class of reversible P2Y(12) inhibitors, recently added to updated ACC and ESC guidelines for use in patients with ACS. The authors review the studies that evaluate the pharmacokinetics, pharmacodynamics, clinical efficacy and safety of ticagrelor in comparison to currently available antiplatelet agents.

EXPERT OPINION

Ticagrelor 180 mg loading dose followed by 90 mg b.i.d. is significantly more efficacious and, in general, as safe as clopidogrel in the treatment of all patients with an ACS regardless of treatment strategy. In addition, besides aspirin compared to placebo, it is the only pharmaceutical intervention shown to have a cardiovascular mortality benefit within 1 year in a broad ACS population. Whether this surprising benefit is realized in other populations is currently being tested.

Towards personalized medicine based on platelet function testing for stent thrombosis patients

Stent thrombosis (ST) is a severe and feared complication of coronary stenting. Patients who have suffered from ST are usually treated according to the “one-size-fits-all” dosing regimen of aspirin and clopidogrel. Many ST patients show high on-treatment platelet reactivity (HPR) despite this antiplatelet therapy (APT). It has been shown that HPR is a risk factor for major adverse cardiac events. Therefore, ST patients with HPR are at a high risk for recurrent atherothrombotic events. New insights into the variable response to clopidogrel and the advent of stronger P2Y12 inhibitors prasugrel and ticagrelor have changed the attention from a fixed APT treatment strategy towards “personalized APT strategies.” Strategies can be based on platelet function testing, which gives insight into the overall response of a patient to APT. At our outpatient ST clinic, we practice personalized APT based on platelet function testing to guide the cardiologist to a presumed optimal antiplatelet treatment of ST patients. Beside results of platelet function testing, comedication, clinical characteristics, and genetics have to be considered to decide on personalized APT. Ongoing studies have yet to reveal the optimal personalized APT strategy for cardiologists to prevent their patients from atherothrombotic and bleeding events.

Randomized Assessment of Ticagrelor Versus Prasugrel Antiplatelet Effects in Patients with ST-Segment–Elevation Myocardial Infarction

Background—

Ticagrelor and prasugrel provide stronger platelet inhibition compared with clopidogrel. Direct pharmacodynamic comparison between them has not yet been reported in ST-segment–elevation myocardial infarction patients.

Methods and Results—

In a prospective, single-center, single-blind study, 55 out of 117 (47%) screened consecutive ST-segment–elevation myocardial infarction patients undergoing primary percutaneous coronary intervention were randomized to either ticagrelor 180 mg loading followed by 90 mg bid, or prasugrel 60 mg loading followed by 10 mg od for 5 days. Platelet reactivity (PR) was assessed with the VerifyNow P2Y12 function assay and the Multiplate Analyzer at 0, 1, 2, 6, 24 hours, and 5 days postrandomization. The primary end point, PR with VerifyNow at hour 1, did not differ significantly between patients randomized to ticagrelor versus prasugrel (257.3 P2Y12 reaction unit [PRU], 95% CI 230.8–283.8 versus 231.3 PRU, 95% CI 205.3–257.4; P =0.2). PR did not differ at 2, 6, and 24 hours, although at day 5 it was lower with ticagrelor than prasugrel (25.6 PRU, 95% CI 12.3–38.9 versus 50.3 PRU, 95% CI 36.4–64.1; P =0.01). At hour 2, high on-treatment PR rates (cutoff 208 PRU) were 46.2% and 34.6% for ticagrelor and prasugrel, respectively, decreased significantly thereafter, whereas did not differ significantly between the 2 agents at all the time points of the study.

Conclusions—

In patients with ST-segment–elevation myocardial infarction undergoing primary percutaneous coronary intervention, both ticagrelor and prasugrel exhibit an initial delay in the onset of their antiplatelet action. Ticagrelor did not appear superior to prasugrel in reducing PR during the first 24 hours of ST-segment–elevation myocardial infarction.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01463163.