Aspirin resistance: mechanisms and clinical implications

Effect of PEAR1, PTGS1 gene polymorphisms on the recurrence of aspirin-treated patients with ischemic stroke in the Han population of China: A 4-year follow-up study

Platelet endothelial aggregation receptor 1 (PEAR1) and prostaglandin endoperoxide synthase 1 (PTGS1) polymorphisms can affect laboratory aspirin resistance. However, the impact of genetic polymorphisms on the recurrence of ischemic stroke (IS) patients treated with aspirin is not fully understood. This study aimed to examine the relationship between gene polymorphisms of PEAR1 and PTGS1 and IS recurrence in patients treated with aspirin. Peripheral blood samples were collected from 174 patients with nonrecurrent IS and 34 with recurrent IS after aspirin treatment. Follow-up was performed on all patients. PEAR1 rs12041331 and PTGS1 rs10306114 polymorphisms were determined using the PCR fluorescence probe method. And the correlations of them with the clinical characteristics were examined by multivariable logistic regression analysis. The distribution frequencies of PEAR1 rs12041331 and PTGS1 rs10306114 genotypes were in Hardy-Weinberg equilibrium, and there was no significant difference in the distribution of PEAR1 rs12041331 polymorphism. Compared to the nonrecurrent group, the AA genotype of the PTGS1 polymorphism was more frequent in the recurrent group (59.77% vs 35.29%, P = .003), and the A allele also showed a higher frequency than the G allele in the recurrent group (P = .001). Multivariable logistic regression analysis showed that smoking (OR = 5.228, 95% CI: 1.938-14.102, P = .001), coronary heart disease (OR = 4.754, 95% CI: 1.498-15.089, P = .008), and the polymorphism at PTGS1(A>G) AA/AG + GG (OR = 2.955, 95% CI: 1.320-6.616, P = .008) were independently associated with IS recurrence in Chinese patients. Our findings suggested that PTGS rs10306114 polymorphisms should receive more attention in the use of aspirin in patients with IS.

Application Progress and Prospect of Herbal and Western Medicine Combined with Antiplatelet Therapy for Cardiovascular Events

Antiplatelet therapy is the key point in the treatment of cardiovascular and cerebrovascular diseases. Effective and safe antiplatelet therapy can avoid the risk of thrombosis or bleeding again. Herbal and Western medicine combined with antiplatelet therapy for ischemic cardiovascular events is a common phenomenon in clinical application, and more and more animal experiments, in vitro cell experiments, and randomized controlled clinical studies have also clarified the efficacy and interaction mechanism of the combination and safety. Herbal and Western medicine combined with antiplatelet therapy has made some progress in improving aspirin resistance and clopidogrel resistance, enhancing antiplatelet and antithrombotic effect, and reducing gastrointestinal adverse reactions caused by antiplatelet drugs. Both of them play the role of antiplatelet and antithrombotic by reducing platelet adhesion, inhibiting platelet activation and aggregation, and inhibiting platelet release, and the combination of drugs is safe. This article elaborates and analyzes the application progress and prospect of Chinese and Western medicine combined with antiplatelet therapy, in order to provide more theoretical support for future research.

Platelet glycoprotein IIIa gene polymorphism (Leu33Pro) and aspirin resistance in a very elderly Chinese population

OBJECTIVES

To study the relationship between platelet glycoprotein IIIa gene (GP IIIa) polymorphism (Leu33Pro) and aspirin resistance in a very elderly Chinese population.

METHODS

Four hundred fifty very elderly Chinese people receiving aspirin therapy were enrolled in the study. Patients who underwent arachnoid acid-induced platelet aggregation were then divided into two groups based on their resistance to aspirin: aspirin-resistant (AR) group (n=236) and aspirin-sensitive (AS) group (n=214). The Leu33Pro polymorphism of the GP IIIa gene was scanned by polymerase chain reaction-restriction fragment-length polymorphism.

RESULTS

In the AR group, 224 participants had the A1/A1 genotype and 12 had the A1/A2 genotype. All patients in the AS group had the A1/A1 genotype. Thus, there was significant difference between these two groups in the genotype distribution (p<0.05).

CONCLUSION

The genetic polymorphism of the GP IIIa gene was associated with AR in a very elderly Chinese population.

A contemporary viewpoint on 'aspirin resistance'

Aspirin is an irreversible inhibitor of platelet prostaglandin synthase activity, and is the most widely prescribed drug for the secondary prevention of cardiovascular disease. In recent years, clinical and laboratory evidence has shown significant individual variability in the response to aspirin and its link to clinical outcome. The term 'aspirin resistance' has been introduced to describe situations when clinical or ex-vivo effects of aspirin are less than expected. The accumulating evidence of increased risk of major adverse clinical events (MACE) associated with 'aspirin resistance' in the settings of acute coronary syndrome (ACS), stroke, and peripheral arterial disease has stimulated the search for ways of overcoming aspirin resistance. Existence of the link between high on-treatment platelet reactivity and atherothrombotic events suggests the common mechanisms for atherosclerosis progression and thrombotic complications with the platelets, being a key cellular interface between coagulation and inflammation. This review article provides a contemporary view on 'aspirin resistance' and discusses its definition, clinical importance, and possible mechanisms in light of recent data on the role of platelets in atherothrombosis.

The impact of upper gastrointestinal symptoms on nonadherence to, and discontinuation of, low-dose acetylsalicylic acid in patients with cardiovascular risk

BACKGROUND

While low-dose acetylsalicylic acid (ASA [aspirin]; 75-325 mg) is a mainstay of cardiovascular (CV) protection in patients at high risk of CV events, such protection may be compromised due to poor adherence (or discontinuation) resulting from gastrointestinal (GI) adverse events. To date, however, the link between GI adverse events and nonadherence to, and discontinuation of, low-dose ASA is not well established in the literature.

OBJECTIVE

The aim of this study was to characterize the real-world impact of upper GI symptoms on low-dose ASA nonadherence and discontinuation in patients with CV risk taking low-dose ASA for CV protection.

STUDY DESIGN

Multicenter, observational, noninterventional study.

SETTING

Primary-care, cardiology, and practice group centers in the US, Canada, and France.

PATIENTS

Subjects aged ≥18 years at risk of, or with confirmed, CV disease, and who had been prescribed or recommended low-dose ASA (75-325 mg daily) by a physician.

MAIN OUTCOME MEASURE

Adherence to low-dose ASA was assessed using 3 months of data prospectively collected using an electronic diary (completed at least three times/day). Adherence was defined as low-dose ASA intake of ≥75% over the 3-month eDiary phase. Discontinuation was defined as no reported low-dose ASA intake for ≥7 continuous days. The odds of daily adherence were calculated using a mixed-model analysis for repeated measures, and a Cox-proportional hazard model was used to assess the association between upper GI symptoms and time to discontinuation of low-dose ASA.

RESULTS

Overall, 340 patients (mean age 50 years; 59% women) participated in the analysis. Most patients (75%) were low-dose ASA naïve at inclusion, and had not experienced upper GI symptoms within the previous 14 days. Among these patients, the onset of upper GI symptoms was rapid; symptoms were reported by 19% of patients on the first day of the study, rising to 46% of patients at the end of the first week. Over the 3-month study period, 18% of patients were nonadherent to low-dose ASA treatment. The occurrence of upper GI symptoms negatively affected low-dose ASA adherence, in both the overall patient population (odds ratio [OR] = 0.84; 95% CI 0.70, 1.0) and among patients who were low-dose ASA naïve at baseline (OR = 0.76; 95% CI 0.57, 1.0). A total of 13% of patients discontinued low-dose ASA therapy. For the overall cohort and for the low-dose ASA-naïve patients at baseline, more than three episodes of upper GI symptoms during the previous week was associated with an increased risk of low-dose ASA discontinuation compared with no episodes of upper GI symptoms during the previous week (hazard ratio [HR] = 2.60; 95% CI 1.00, 6.80, and HR = 7.52; 95% CI 2.57, 22.04, respectively).

CONCLUSIONS

Upper GI symptoms can lead to nonadherence to, and discontinuation of, low-dose ASA CV-protective therapy. Patients who initiate low-dose ASA may experience an early onset of upper GI symptoms. (

TRIAL REGISTRATION NUMBER

NCT00681759 [ClinicalTrials.gov Identifier]; AstraZeneca study code: D961FC00004).

Dose-related effect of aspirin on laboratory-defined platelet aggregation and clinical outcome after coronary stenting

BACKGROUND

Acetylsalicylic acid (aspirin) is widely used in the secondary prevention of coronary artery disease. There is controversy regarding the prevalence of aspirin resistance in patients with coronary artery disease and the effect of dose on resistance. Our primary aims were to determine the degree of platelet responsiveness to aspirin, and to study the influence of dose on platelet inhibition and clinical outcomes after coronary stenting.

METHODS AND RESULTS

We prospectively studied the effect of aspirin on platelet function in 106 stable outpatients 6 months after successful percutaneous coronary angioplasty. Participants were randomized in a double-blind, double-crossover study (80 or 500 mg per day for 6 months). The platelet response to aspirin was determined by 10 micromol/L adenosine-5-diphosphate-induced aggregation with light transmission aggregometry. The clinical outcome was determined by single photon emission computed tomography with Tc-99m, and major adverse cardiac events were recorded (myocardial infarction, death, unstable angina or need for revascularization). In both groups 30.2% of the participants were resistant to aspirin. There was no significant difference between the dose of 80 mg compared to 500 mg aspirin in the incidence of aspirin resistance (P= 0.3). No correlation was found between aspirin resistance and clinical outcome (P= 0.4). Female sex and smoking were strongly associated with aspirin resistance.

CONCLUSION

The frequency of aspirin resistance is not dependent on the dose of aspirin. Female sex and smoking were the strongest predictors of aspirin resistance. Aspirin resistance is not a predictor of poor clinical outcome in patients who received double antiplatelet therapy.

Diabetes, vascular complications and antiplatelet therapy: open problems

Diabetes mellitus is commonly associated with both microvascular and macrovascular complications (coronary artery disease, cerebrovascular events, severe peripheral vascular disease, nephropathy and retinopathy). There is wide evidence demonstrating that platelet degranulation and synthesis of TxA2 are increased in diabetic patients. For this reason, many studies on anti-platelet therapy have been made to reduce thrombotic complication of diabetes mellitus. Some diabetic patients, although treated with ASA, have a high prevalence of recurrent thrombotic events, which may presumably be due to an "ASA resistance". Nevertheless, this drug remains the one with the greatest benefit. To optimize its function, we should try to understand the causes of "aspirin resistance", try to find the most suitable dosage, recommending patients to comply constantly with the prescription given and to avoid interactions with other drugs. "Clopidogrel resistance" is a term not clearly defined. The clinical implications of "clopidogrel resistance" are unknown. An important consideration affecting the use of aspirin in diabetic patients is its interaction with ACE-inhibitors. Another question is antiplatelet therapy in nephropathic diabetic patients. Although these patients are at high thrombotic and haemorrhagic risk, they should nevertheless be considered eligible to undergo antithrombotic therapy, taking into account the individual's haemorrhagic risk.

Higher Thrombelastograph platelet reactivity in cardiac surgery patients than in blood donors

OBJECTIVES

Platelet reactivity, evaluated by Thrombelastograph (TEG) predicts the recurrence of ischemic events in patients undergoing percutaneous coronary intervention (PCI). The aim of this study was to investigate the platelet hyperreactivity and the variability in platelet reactivity due to ADP in cardiac surgery patients and donors.

METHODS

Preoperative blood samples from 22 patients undergoing CABG surgery and 43 blood donors were analysed by the TEG Platelet Mapping assay. Maximal platelet reactivity and platelet reactivity response to ADP stimulation (MAADP) were evaluated.

RESULTS

Maximal platelet reactivity (MAThrombin) and MAADP was higher in the CABG patients than in the blood donors, p=0.001 for MAThrombin and p<0.0001 for MAADP. Six patients (27.2%) had a MAThrombin above the normal reference range compared to only one (2.3%) of the healthy donors (p=0.005).

CONCLUSIONS

The identification of a higher subpopulation of CABG patients compared to donors presenting with platelet reactivity above the normal range together with increased platelet responsiveness to ADP may reflect the higher risk for ischemic events in this cohort.

Review: Aspirin and Diabetes Mellitus: revisiting an old player

Type 2 Diabetes Mellitus confers an excess risk of cardiovascular disease. The mechanisms involved in the development of the disease are an active field of research, and prompt the development of newer and safer therapeutics with implications for cardiovascular disease. Currently there is increasing awareness of the role of platelet dysfunction, low-grade chronic inflammation and thrombogenesis in the pathophysiology of insulin resistance, T2DM, as well as type 1 diabetes mellitus and cardiovascular disease. This new evolving knowledge has allowed a better understanding of the role of aspirin, an old medication with proven beneficial effects on patients with established cardiovascular disease. The influence of salicylates on insulin resistance, glucose homeostasis, platelet function and inflammatory pathways, in particular related to the activation of the NF κB pathway, is a promising field of active research, and will help in the management of both diabetes mellitus and atherosclerotic-related cardiovascular disease.

Aspirin and bleeding in dentistry: an update and recommendations

Aspirin use in the United States remains high because of its diverse and beneficial activities. In adults at risk for cardiovascular thrombotic events, low-dose aspirin is an excellent preventive agent; however, its antiplatelet properties have contributed to a perceived increased risk for bleeding after dental extractions. This article discusses recent evidence regarding the thrombotic risks associated with discontinuing aspirin use in patients who take aspirin daily and presents a new recommendation for continuing low-dose aspirin during invasive dental procedures.