The prevalence and factors associated with aspirin resistance in patients premedicated with aspirin

Postoperative myocardial injury and platelet reactivity in patients undergoing vascular surgery: The platelet reactivity and postoperative myocardial injury after major vascular surgery (PROMISE) study

BACKGROUND

Postoperative myocardial injury (PMI) after major vascular surgery, detected by elevated cardiac troponin (cTn), has been associated with morbidity and mortality. It is unclear whether the pathophysiology of PMI is determined by increased platelet activity.

OBJECTIVE

To examine the relationship between platelet activation (P-selectin expression) and PMI in patients undergoing elective open abdominal aortic surgery.

METHODS

This prospective, single-centre, observational, cohort study included 33 patients undergoing elective open abdominal aortic surgery between March 2018 and April 2021. Patients were routinely treated with aspirin. Unstimulated platelet activation was measured by platelet bound P-selectin expression (range 0-100 %). Explorative coagulation measurements were: stimulated platelet aggregation measured with the VerifyNow® assay (aspirin cartridge), with the Multiplate® analyzer (ASPI, ADP and TRAP) and stimulated coagulation status evaluated by the TEG® Hemostasis Analyzer System (global hemostasis cartridge). The primary outcome was cTn release assessed by the fifth generation high-sensitive cTn assay. Multivariable generalized linear mixed models were used to evaluate the association between platelet function and cTn concentrations over time.

RESULTS

Ten patients (30.3 %) developed PMI. Increased P-selectin expression directly after surgery was associated with the cTn concentrations over 48 h (β = 1.39 (1.1-1.75), P = 0.0064). No association was found between P-selectin measured later after surgery (at 24 h or 48 h) and cTn concentrations. Furthermore, there was no association between the explorative coagulation parameters and cTn release.

CONCLUSION

Platelet reactivity, assessed by P-selectin expression measured directly after surgery is associated with PMI, assessed by elevated cTn concentrations in the early postoperative period in patients undergoing elective open abdominal aortic surgery.

Mechanism of Improving Aspirin Resistance: Blood-Activating Herbs Combined With Aspirin in Treating Atherosclerotic Cardiovascular Diseases

Atherosclerotic thrombotic disease continues to maintain a high morbidity and mortality rate worldwide at present. Aspirin, which is reckoned as the cornerstone of primary and secondary prevention of atherosclerotic cardiovascular diseases (ASCVDs), has been applied in clinics extensively. However, cardiovascular events continue to occur even though people utilize aspirin appropriately. Therefore, the concept of aspirin resistance (AR) was put forward by scholars, which is of great significance for the prediction of the clinical outcome of diseases. The pathogenesis of AR may be incorporated with low patient compliance, insufficient dose, genetic polymorphism, increased platelet transformation, inflammation, and the degenerative changes and calcification of platelets. The improvement of AR in the treatment of ASCVDs has gradually become a research hot spot in recent years. Traditional Chinese medicine (TCM) regards individuals as a whole and treats them from a holistic view, which has been found to have advantages in clinical studies on the treatment of AR. Many kinds of blood-activating TCM have the effect of improving AR. The potential mechanism for the improvement of AR by blood-activating herbs combined with aspirin was explored. The combination of blood-activating herbs and aspirin to improve AR is likely to turn into a hot topic of research in the future.

Why Me? To Be an Ultra-Responder to Antiplatelet Therapy: A Case Report

Background: Platelet function testing is a valid tool to investigate the clinical response to antiplatelet therapy in different clinical settings; in particular, it might supply helpful information in patients with cerebrovascular disease. Oral antiplatelet treatment, such as Aspirin (ASA) and Clopidogrel, is the gold standard in secondary stroke prevention of non-cardiogenic ischemic stroke; conversely, its application as a primary prevention therapy is not routinely recommended in patients with vascular risk factors. Multiple electrode platelet aggregometry (MEA) impedance aggregometer is a validated device to test platelet inhibition induced by ASA or Clopidogrel.

Case Report: We report the case of a 78-year-old patient without relevant clinical history, taking ASA as primary prevention strategy, who was admitted for sudden onset of dysarthria and left facial hyposthenia during physical effort. Brain CT revealed two small subcortical bilateral spontaneous intracranial hemorrhages. Platelet aggregometry with MEA performed upon admission revealed a very strong platelet inhibition induced by ASA (result of the ASPI Test was 5 U, consistent with an ultra-responsiveness to ASA, and the cutoff value of correct responsiveness is <40 U). MRI at longitudinal follow-up revealed the presence of two small cavernous angioma underlying hemorrhagic spots.

Conclusion: The evaluation of platelet reactivity in stroke patients undergoing antiplatelet therapies, not commonly performed in clinical practice, could be useful to optimize prevention strategies; the verification of the biological effectiveness of ASA or Clopidogrel could be a valid tool in the definition of each patient's risk profile, particularly in patients with cerebrovascular disease known to be at increased risk for both hemorrhagic and thrombotic complications.

[Evaluation of treatment adaptation for low response to ASA in vascular surgery]

Hintergrund

Eine verminderte antithrombozytäre Prophylaxe („Low-Response [LR]“/„high on-treatment platelet reactivity [HPR]“) mit Acetylsalicylsäure (ASS) ist mit einem erhöhten Risiko für thrombembolische Ereignisse assoziiert. Die Prävalenz einer Low-Response ist mit ca. 20 % häufig und ein Therapieregime wurde bisher noch nicht etabliert. Das Ziel dieser prospektiven Studie war es, die Effektivität eines Therapieschemas zur Therapieanpassung bei detektierter LR/HPR bei gefäßchirurgischen Patienten zu evaluieren.

Methodik

Insgesamt wurden 36 gefäßchirurgischen Patienten mit einer antithrombozytären Dauermedikation mit ASS 100 mg/Tag und einer nachgewiesenen ASS-Low-Response (ALR) in die Studie eingeschlossen. Entsprechend dem festgelegten Therapieplan wurde bei diesen Patienten eine Therapieanpassung durchgeführt und eine Kontrollaggregometrie zur Erfolgskontrolle durchgeführt. Das verwendete Therapieschema folgte dem Test-and-treat-Prinzip. Zur Beurteilung der Wirkung von ASS diente die Impedanzaggregometrie mittels Mehrelektrodenaggregometer (Multiplate).

Ergebnisse

Insgesamt konnten alle 36 Patienten erfolgreich in eine Response überführt werden. Bei 32 (88,89 %) Patienten erfolgte eine Dosiserhöhung auf 300 mg ASS, 2 (5,56 %) Patienten wurden von ASS auf Clopidogrel umgestellt. Bei weiteren 2 (5,56 %) Patienten wurde auf eine orale Antikoagulation mit Phenprocoumon aufgrund anderer Indikationen umgestellt. Blutungskomplikationen oder Nebenwirkungen traten nicht auf.

Schlussfolgerung

Das gewählte Therapieschema zur Behandlung einer Low-Response erwies sich als effektiv und sicher bei gefäßchirurgischen Patienten. Überwiegend führte eine leitliniengerechte Dosiserhöhung der Prophylaxe von 100 mg auf 300 mg ASS zu einer effektiven Thrombozytenaggregationshemmung in der Aggregometrie.

Perioperative changes of response to antiplatelet medication in vascular surgery patients

Introduction

Reduced antiplatelet activity of aspirin (ALR) or clopidogrel (CLR) is associated with an increased risk of thromboembolic events. The reported prevalence data for low-responders vary widely and there have been few investigations in vascular surgery patients even though they are at high risk for thromb-embolic complications. The aim of this prospective observational monocentric study was to elucidate possible changes in ALR or CLR after common vascular procedures.

Methods

Activity of aspirin and clopidogrel was measured by impedance aggregometry using a multiple electrode aggregometer (Multiplate®). Possible risk factors for ALR or CLR were identified by demographical, clinical data and laboratory parameters. In addition, a follow-up aggregometry was performed after completion of the vascular procedure to identify changes in antiplatelet response.

Results

A total of 176 patients taking antiplatelet medications aspirin and/or clopidogrel with peripheral artery disease (PAD) and/or carotid stenosis (CS) were included in the study. The prevalence of ALR was 13.1% and the prevalence of CLR was 32% in the aggregometry before vascular treatment. Potential risk factors identified in the aspirin group were concomitant insulin medication (p = 0.0006) and elevated C-reactive protein (CRP) (p = 0.0021). The overall ALR increased significantly postoperatively to 27.5% (p = 0.0006); however, there was no significant change in CLR that was detected. In a subgroup analysis elevation of the platelet count was associated with a post-procedure increase of ALR incidence.

Conclusion

The incidence of ALR in vascular surgery patients increases after vascular procedures. An elevated platelet count was detected as a risk factor. Further studies are necessary to analyse this potential influence on patency rates of vascular reconstructions.

Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers in Acute Coronary Syndrome: Implications for Platelet Reactivity?

BACKGROUND

In patients with acute coronary syndrome (ACS), angiotensin-converting enzyme (ACE) inhibitors are preferred over angiotensin receptor blockers (ARBs). However, in a recent pilot study, treatment with ACE inhibitors was associated with increased platelet reactivity compared to ARBs. Therefore, we sought to investigate the impact of renin-angiotensin-aldosterone system (RAAS) blockade with ACE inhibitors and ARBs on platelet aggregation in patients with ACS undergoing percutaneous coronary intervention.

METHODS

On-treatment residual platelet reactivity in response to arachidonic acid (AA), adenosine diphosphate (ADP), SFLLRN, AYPGKF, and collagen was assessed by multiple electrode aggregometry (MEA) in 197 ACS patients on dual antiplatelet therapy (DAPT) with aspirin and either prasugrel or ticagrelor.

RESULTS

One hundred sixty-five (83.7%) patients were treated with ACE inhibitors, 32 (16.3%) with ARBs. On-treatment residual AA- and ADP-inducible platelet reactivity was significantly higher in patients with ACE inhibitors (both p < 0.05). Likewise, SFLLRN was significantly higher in patients with ACE inhibitors (p = 0.036) and there was a trend for higher AYPGKF- and collagen-inducible platelet reactivity (p = 0.053 and p = 0.082). The incidence of high on-treatment residual platelet reactivity AA was significantly higher in patients with ACE inhibitors (52 [31.5%] vs. 3 [9.4%] patients; p = 0.019).

CONCLUSION

ACE inhibitors are associated with increased on-treatment residual platelet reactivity in ACS patients with potent DAPT. Further clinical trials are needed to elucidate the role of RAAS blockade with ACE inhibitors and ARBs in ACS patients treated according to current standards.

Resistance to Antiplatelet Therapy Is Associated With Symptoms of Cerebral Ischemia in Carotid Artery Disease

Background:

Platelet inhibitory therapy is prescribed to prevent arterial thromboembolism in patients with atherosclerotic disease. Although taken by millions of people, around 30% are resistant to the treatment they are being prescribed.

Aims:

To determine whether symptoms of cerebral ischemia, or pre-operative cerebral emboli, in patients admitted for a carotid endarterectomy were associated with resistance to aspirin or clopidogrel.

Methods:

Venous blood from 133 patients immediately before carotid endarterectomy (CEA) was analyzed for resistance to aspirin and clopidogrel by multiplate impedance aggregometry. The number of emboli/hour entering the ipsilateral middle cerebral artery was counted by transcranial Doppler (TCD) on the day before surgery in 33 of these patients.

Results:

Resistance was found in 21 (26.3%) of 100 patients taking aspirin and 14 (42%) of 33 taking clopidogrel. Mean (sd) residual platelet aggregation was significantly higher at 41.9(32) Au in patients who had suffered recent symptoms of cerebral ischemia compared with 30.8(16) Au in asymptomatic patients (p = 0.012). Residual platelet aggregation also correlated significantly with the number of emboli/hour counted by TCD in the ipsilateral middle cerebral artery (r = 0.45, p = 0.009).

Conclusion:

Antiplatelet resistance was associated with the frequency of cerebral emboli and recent symptoms of cerebral ischemia in patients with carotid disease. Definitive clinical studies are needed to explore whether testing for antiplatelet resistance should be undertaken routinely in patients starting platelet inhibitory therapy for cardiovascular disease.

Resistance of aspirin during and after pregnancy: A longitudinal cohort study

OBJECTIVES

The objective of this study is to investigate possible changes in aspirin resistance during and after pregnancy over time.

STUDY DESIGN

A longitudinal cohort study in obstetric high risk women with an indication for aspirin usage during pregnancy to prevent placenta mediated pregnancy complications.

MAIN OUTCOME MEASURES

Aspirin resistance measured in the first, second and third trimester of pregnancy and at least three months postpartum by four complementary test: PFA-200, VerifyNow®, Chronolog light transmission aggregometry (Chronolog LTA) and serum thromboxane B₂ (TxB₂) level measurements. Correlation between the devices was investigated.

RESULTS

In total, 23 pregnant women participated in the present study. Aspirin resistance according to the PFA-200, VerifyNow®, Chronolog LTA and serum TxB₂, was 30.4%, 17.4%, 26.1% and 23.8% respectively. Resistance by any device was 69.6%. Aspirin resistance measured by the VerifyNow®, Chronolog LTA, serum TxB₂ and aspirin resistance by any device during pregnancy was demonstrated more frequently than aspirin resistance after pregnancy. Correlation between the different devices was weak.

CONCLUSION

Aspirin resistance was found in a considerable part of the participants. Considerable variation between participants, within participants over time and between the different devices was found. Prevalence of aspirin resistance during pregnancy differs from after pregnancy. More research on aspirin resistance and clinical obstetric outcome is needed.

Evaluation of platelet activity by multiple electrode impedance aggregometry in acute coronary syndromes: pilot study in a Brazilian tertiary-care public hospital

There is no definite recommendation for testing platelet aggregation (PA) in acute coronary syndromes (ACS) due to inconclusive evidence on the usefulness of platelet function tests to guide therapy and improve clinical outcomes. The evaluation of PA with multiple electrode impedance platelet aggregometry (MEA) may be useful to manage antiplatelet therapy and possibly influence patient outcome. The primary aim of this study was to measure PA with MEA in Brazilian patients with ACS and evaluate the association between PA and adverse clinical outcomes. Forty-seven consecutive patients admitted with ACS to a Brazilian tertiary-care public hospital were studied and PA was evaluated using MEA. Patients were followed for six months for the occurrence of all-cause death, acute myocardial infarction, or stroke. Suboptimal inhibition of PA was found in 7 patients (14.9%); 5 (10.6%) in response to ASA (acetylsalicylic acid), 2 (5.0%) to clopidogrel, and none to ticagrelor. Inadequate PA inhibition in response to ASA was significantly associated with the composite end point, but there was no significant association for insufficient PA inhibition in response to clopidogrel. This study suggested that the evaluation of PA in ACS using MEA may identify non-responders to ASA. Larger studies are necessary to define, in a public health scenario, the value of MEA in the management of ACS.

Multiplate® evaluation of acetylsalicylic acid efficacy in carotid surgery: routine and genetic influencing factors

Essentials Acetylsalicylic acid (ASA) is prescribed to patients scheduled for carotid endarterectomy (CEA). We measured ASA efficacy during CEA by Multiplate® and searched for influencing factors. Most patients scheduled for CEA and treated by ASA are sensitive to this therapy. Influencing genomic factors are involved in ASA metabolism and in platelet function modulations.

SUMMARY

Background Acetylsalicylic acid (ASA) is recommended before, during and after carotid endarterectomy (CEA). The efficacy of ASA is influenced by numerous biological and genotypic factors. Objectives To determine the biological efficacy of ASA by using the Multiplate® method, and to explore the biological parameters and genomic factors influencing this efficacy. Methods This descriptive cross-sectional study included all patients scheduled for CEA between January 2012 and April 2013. Multiplate® tests were performed at day 0 and day 30. A set of 66 single-nucleotide polymorphisms (SNPs) from 38 genes or DNA regions were selected and studied along with phenotypic parameters by the use of hierarchical clustering (HC) for multidimensional data management. Results Fifty-five patients receiving ASA were analyzed. Of the patients, 95% were found to be sensitive to ASA, with values under the threshold of normality (400 AU min-1 ). However, there were notable differences in residual aggregation among subjects over a wide range. HC revealed four subclusters comprising three categories of parameters: (i) routine and functional parameters - in ASA-treated patients, the ASPItest was highly linked to the ADPtest, to platelet count, and, to a lesser extent, to fibrinogen and hematocrit; (ii) polymorphisms in genes involved in ASA absorption and in the arachidonic acid pathway (ABCB1 and COX-1); and (iii) polymorphisms in genes modulating basal platelet function, i.e. TBXA2R, ADRA2A, PEAR1, ITGA2 and ITGB1. Conclusion Most patients treated with ASA before CEA were sensitive to it, according to Multiplate® ASPItest results. Genomic factors influencing this efficacy are SNPs involved in ASA absorption and metabolic pathway, and in modulations in basal platelet function.

[Prevalence of acetylsalicylic acid (ASA) - low response in vascular surgery]

BACKGROUND

Research has revealed that a decreased antiplatelet effect (low response [LR]/high on-treatment platelet reactivity [HPR]) of acetylsalicylic acid (ASA) and clopidogrel is associated with an increased risk of thromboembolic events. There are extensive ASA low response (ALR) and clopidogrel low response (CLR) prevalence data in the literature, but there are only a few studies concerning vascular surgical patients. The aim of this study was to examine the prevalence and risk factors of ALR and CLR in vascular surgical patients.

MATERIALS AND METHODS

We examined n = 154 patients with an antiplatelet long-term therapy, who were treated due to peripheral artery occlusive disease (PAD) and/or arteria carotis interna stenosis (CVD). To detect an ALR or CLR, we examined full blood probes with impedance aggregometry (ChronoLog® Aggregometer model 590). Risk factors were examined by acquisition of concomitant disease, severity of vascular disease, laboratory test results and medication.

RESULTS

We found a prevalence of 19.3 % in the ALR group and of 21.1 % in the CLR group. Risk factors for ALR were an increased platelet and leucocyte count and co-medication with pantoprazole. We found no significant risk factors for a decreased antiplatelet effect of clopidogrel treatment.

CONCLUSION

The investigated prevalence for ALR and CLR are in the range of other studies, particularly based on cardiological patients. More investigations are needed to gain a better evaluation of the risk factors for HPR and to develop an effective antiplatelet therapy regime to prevent cardiovascular complications.

PFA-100-measured aspirin resistance is the predominant risk factor for hospitalized cardiovascular events in aspirin-treated patients: A 5-year cohort study

WHAT IS KNOWN AND OBJECTIVE

Aspirin therapy is the clinical gold standard for the prevention of cardiovascular events. However, cardiovascular events still develop in some patients undergoing aspirin therapy. Many laboratory methods exist for measuring aspirin resistance. Using the platelet Function Analyzer (PFA)-100 system, we aimed to determine the effect of aspirin resistance on hospitalized cardiovascular events (hCVE) in a 5-year follow-up cohort. We also sought to determine the impact of aspirin resistance on the relationship between common cardiovascular risk factors and cardiovascular hospitalization.

METHOD

Aspirin resistance was evaluated in aspirin-treated patients from the outpatient department. A total of 465 patients during a 5-year follow-up period were included in this study. The primary endpoint of the study was hospitalization for any acute cardiovascular event. The prevalence and associated risk factors of acute cardiovascular events were evaluated.

RESULTS AND DISCUSSION

Aspirin resistance was prevalent in 91 (20.0%) of 465 patients. Prior hospitalization history of cardiovascular events was highly associated with aspirin resistance (P = .001). At the 5-year follow-up, cardiovascular events were found to have developed in 11 patients (8 stroke and 3 myocardial infarction) who exhibited aspirin resistance (12.1%) and in 9 (4 stroke and 5 myocardial infarction) patients who did not exhibit aspirin resistance (2.4%) (P < .001). At the 5-year follow-up, multivariate logistic regression analysis results showed a strong association between aspirin resistance and cardiovascular events (adjusted odds ratio 4.28; 95% CI: 1.64-11.20; P = .03).

WHAT IS NEW AND CONCLUSION

PFA-100 measurements of aspirin resistance correlate with hCVE, as evidenced by both the past medical history and the 5-year follow-up. The logistic regression analysis results showed that aspirin resistance plays a larger role in hospitalized cardiovascular disease than do other cardiovascular risk factors.

Recurrent Cardiovascular Events Despite Antiplatelet Therapy in a Patient with Polycythemia Vera and Accelerated Platelet Turnover

Patient: Male, 58

Final Diagnosis: STEMI

Symptoms: Angina pectoris

Medication:—

Clinical Procedure: —

Specialty: Hematology

The incidence of aspirin resistance in heart transplantation recipients

Introduction

Coronary allograft vasculopathy can cause as many deaths as infections or rejection episodes within 3 years following heart transplantation.

Aim

To compare the aspirin resistance rate in an allograft heart transplantation population and in a control group by laboratory tests including the Aspirin-Resistant Patients Identification Test (ASPItest).

Material and methods

A total of 24 heart recipients (20 men and 4 women) at a mean age of 48 ±13 years who underwent routine clinical follow-up were consecutively enrolled in group 1. The control group consisted of 24 patients (19 men and 5 women) at a mean age of 64 ±7 years waiting for coronary artery bypass grafting in our department. All patients were treated with a standard dose of 75 mg aspirin (ASA) daily.

Results

Aspirin resistance was evaluated by the Multiplate platelet function test. The ASPItest revealed a mean value of 27 ±22 U in the transplant group. Results above 30 U were obtained in 8 (34%) patients, with a mean value of 50.3 ±20.6 U, indicating aspirin resistance. In the control group ASPItest results above 30 U were obtained in 5 (20%) patients, with a mean value of 43.3 ±6.4 U.

Conclusions

There is a high incidence (34% vs. 20%, NS) of ASA resistance in heart transplantation recipients and in the general population, respectively.

Characterisation of clot microstructure properties in stable coronary artery disease

Background

Coronary artery disease (CAD) is associated with an increased prothrombotic tendency and is also linked to unfavourably altered clot microstructure. We have previously described a biomarker of clot microstructure (d_f) that is unfavourably altered in acute myocardial infarction. The d_f biomarker assesses whether the blood will form denser or looser microstructures when it clots. In this study we assessed in patients with stable chest pain whether d_f can differentiate between obstructed and unobstructed CAD.

Methods

A blood sample prior to angiography was obtained from 251 consecutive patients undergoing diagnostic coronary angiography. Patients were categorised based on angiographic findings as presence or absence of obstructive CAD (stenosis ≥50%). The blood sample was assessed using the d_f biomarker, standard laboratory markers and platelet aggregometry (Multiplate).

Results

A significant difference (p=0.028) in d_f was observed between obstructive CAD (1.748±0.057, n=83) and unobstructive CAD (1.732±0.052, n=168), where patients with significant CAD produce denser, more tightly packed clots. d_f was also raised in men with obstructive CAD compared with women (1.745±0.055 vs 1.723±0.052, p=0.007). Additionally d_f significantly correlated with the platelets response to arachidonic acid as measured by the ASPItest area under the curve readings from platelet aggregometry (correlation coefficient=0.166, p=0.008), a low value of the ASPItest indicating effective aspirin use was associated with looser, less dense clots.

Conclusions

For the first time, we characterise clot microstructure, as measured by d_f, in patients with stable CAD. d_f can potentially be used to risk-stratify patients with stable CAD and assess the efficacy of therapeutic interventions by measuring changes in clot microstructure.

Post-pregnancy aspirin resistance appears not to be related with recurrent hypertensive disorders of pregnancy

OBJECTIVE

The FRUIT-RCT concluded that low-molecular-weight heparin added to aspirin compared to treatment with aspirin alone is beneficial in the prevention of early-onset hypertensive disorders of pregnancy (HD) in women with inheritable thrombophilia and prior HD and/or a small-for-gestational age (SGA) infant leading to delivery before 34 weeks gestation. The aim of this study is to answer the question whether aspirin resistance is associated with recurrent HD.

STUDY DESIGN

Women with and without recurrent HD matched for age, study arm, and chronic hypertension were invited for this follow-up study 6-16 years after they participated in the FRUIT-RCT. Aspirin resistance was tested after 10days of aspirin intake using three complementary tests: PFA-200, VerifyNow^® and serum thromboxane B₂ (TXB₂). An independent t-test, Mann-Whitney U test, Fisher's Exact test and Chi² test were used for the statistical analyses.

RESULTS

Thirteen of 24 women with recurrent HD and 16 of 24 women without recurrent HD participated. The prevalence of laboratory aspirin resistance was 34.5% according to the PFA-200, 3.4% according to the VerifyNow^® and 24.1% according to TXB₂. The prevalence of aspirin resistance by any test was 51.7%. Aspirin resistance per individual test did not differ between women with and without recurrent HD. Aspirin resistance measured by any test occurred more frequently in women without recurrent HD (p<0.01), irrespective of low-molecular-weight heparin.

CONCLUSIONS

No relation could be demonstrated between recurrent HD and aspirin resistance per test, measured up to 16 years after pregnancy. On the contrary, complementary aspirin resistance measurements were encountered more frequently in women without recurrent HD.

Assessment of platelet function in patients with stroke using multiple electrode platelet aggregometry: a prospective observational study

Background

There is a link between high on-treatment platelet reactivity (HPR) and adverse vascular events in stroke. This study aimed to compare multiple electrode platelet aggregometry (MEA), in healthy subjects and ischaemic stroke patients, and between patients naive to antiplatelet drugs (AP) and those on regular low dose AP. We also aimed to determine prevalence of HPR at baseline and at 3–5 days after loading doses of aspirin.

Methods

Patients with first ever ischaemic stroke were age and sex-matched to a healthy control group. Three venous blood samples were collected: on admission before any treatment given (baseline); at 24 h and 3–5 days after standard treatment. MEA was determined using a Mutliplate® analyser and agonists tested were arachidonic acid (ASPI), adenosine diphosphate (ADP) and collagen (COL).

Results

Seventy patients (mean age 73 years [SD 13]; 42 men, 28 women) were age and sex-matched to 72 healthy subjects. Thirty-three patients were on antiplatelet drugs (AP) prior to stroke onset and 37 were AP-naive. MEA results for all agonists were significantly increased in AP-naive patients compared to healthy subjects: ADP 98 ± 31 vs 81 ± 24, p < 0.005; ASPI 117 ± 31 vs 98 ± 27, p < 0.005; COL 100 ± 25 vs 82 ± 20, p < 0.005. For patients on long term AP, 33% (10/30) of patients were considered aspirin-resistant. At 3–5 days following loading doses of aspirin, only 11.1% were aspirin resistant based on an ASPI cut-off value of 40 AU*min.

Conclusions

Many patients receiving low dose aspirin met the criteria of aspirin resistance but this was much lower at 3–5 days following loading doses of aspirin. Future studies are needed to establish the causes of HPR and potential benefits of individualizing AP treatment based on platelet function testing.

High prevalence of aspirin resistance in elderly patients with cardiovascular disease and metabolic syndrome

Background

Metabolic syndrome is known to be a prothrombotic state. We undertook this study to examine a hypothesis that aspirin resistance may be associated with metabolic syndrome, and to assess other potential determinants of aspirin resistance in patients with cardiovascular disease (CVD).

Methods

A total of 469 elderly patients with CVD were recruited. One hundred and seventy-two patients with metabolic syndrome and 297 without metabolic syndrome (control group) received daily aspirin therapy (≥ 75 mg) over one month. Platelet aggregation was measured by light transmission aggregometry (LTA). Aspirin resistance was defined as ≥ 20% arachidonic acid (AA)- and ≥ 70% adenosine diphosphate (ADP)-induced aggregation according to LTA. Aspirin semi-responders were defined as meeting one (but not both) of these criteria.

Results

By LTA, 38 of 469 (8.1%) patients were aspirin resistant. The prevalence of aspirin resistance was higher in the metabolic syndrome group compared with the control group [11.6 % vs. 6.6%, odds ratio (OR) = 2.039; 95% confidence interval (CI): 1.047–3.973]. In the multivariate logistic regression analysis, metabolic syndrome (OR = 4.951, 95% CI: 1.440–17.019, P = 0.011) was a significant risk factor for aspirin resistance.

Conclusions

A significant number of patients with CVD and metabolic syndrome are resistant to aspirin therapy. This might further increase the risk of cardiovascular morbidity and mortality in these patients.

Laboratory-Based Markers as Predictors of Brain Infarction During Carotid Stenting: a Prospective Study

AIM

New ischemic lesions in the brain can be detected in approximately 50% of patients undergoing carotid artery stenting (CAS). We wished to discover the laboratory-based predictors of new infarctions in the brain after CAS.

METHODS

All consecutive patients with internal carotid artery stenosis of ≥70% with indication for CAS were enrolled in a prospective study for 16 months. All patients used dual antiplatelet therapy for ≥7 days before CAS. Neurologic examination and magnetic resonance imaging (MRI) of the brain were undertaken before and at 24 h after CAS. Samples of venous blood were collected at ＜24 h before CAS for the evaluation of hematology, reticulocytes, coagulation markers (PT, APTT, Fbg, Clauss), vWF antigen, PAI-1 activity, PAI-1 polymorphism 4G/5G, and the multiplate (aspirin and clopidogrel) resistance test. Blood samples for the assessment of anti-Xa activity were collected during CAS. Differences in the values of laboratory markers between patients with and without new ischemic lesions of the brain on control MRI were evaluated.

RESULTS

The cohort comprised 81 patients (53 males; mean age, 67.3±7.2 years). New ischemic infarctions in the brain on control MRI were found in 46 (56.8%) patients. Three of seven patients with resistance to aspirin or clopidogrel had a new ischemic infarction in the brain. No significant differences for particular markers were found between patients with and without an ischemic lesion in the brain.

CONCLUSION

A high risk of a new ischemic infarction in the brain was detected in patients undergoing CAS, but a laboratory-based predictor of such an infarction could not be identified.

Aspirin resistance may be identified by miR-92a in plasma combined with platelet distribution width

OBJECTIVE

Aspirin is a widely used drug for prevention of thrombotic events in cardiovascular patients, but approximately 25% of patients experience insufficient platelet inhibition due to aspirin, and remain in risk of cardiovascular events. This study aimed to investigate the value of circulating miR-92a and platelet size as biomarkers of the individual response to aspirin therapy.

METHODS

Blood samples were collected from 50 healthy blood donors without antithrombotic medication and 50 patients with intermittent claudication on daily aspirin therapy. Based on results from the arachidonic acid stimulated aggregation test on Multiplate®analyzer (ASPItest), patients were defined as aspirin resistant (n=10) or aspirin responders (n=40). Plasma levels of miR-92a were evaluated by RT-qPCR analysis and platelet distribution width (PDW) was used to assess platelet size variability. Receiver operating characteristic curves for miR-92a levels and PDW were used to set cut-off values for discrimination between aspirin responding and aspirin resistant patients.

RESULTS

When defining aspirin resistance as an ASPItest ≥30U, the optimal cut-off values for discrimination of aspirin responders and aspirin resistant patients were found to be PDW>11.8fL and a relative expression level of miR-92a>4.5. Using these cut-off values we could define a PDW/miR-92a-score with a specificity of 97.5% and a sensitivity of 80.0% in relation to detect aspirin resistance. The corresponding positive and negative predictive values were found to be 88.9% and 95.1%, respectively.

CONCLUSION

Aspirin resistance can potentially be identified by miR-92a levels in plasma combined with PDW.

Individualising dual antiplatelet therapy after percutaneous coronary intervention: the IDEAL-PCI registry

OBJECTIVE

To evaluate the clinical utility of individualising dual antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI) in an all-comers population, including ST-elevation myocardial infarction (STEMI) patients.

SETTING

Tertiary care single centre registry.

PARTICIPANTS

1008 consecutive PCI patients with stent implantation, without exclusion criteria.

INTERVENTION

Peri-interventional individualisation of DAPT, guided by multiple electrode aggregometry (MEA), to overcome high on-treatment platelet reactivity (HPR) to ADP-induced (≥50 U) and arachidonic acid (AA)-induced aggregation (>35 U).

OUTCOME MEASURES

The primary efficacy end point was definite stent thrombosis (ST) at 30 days. The primary safety end point was thrombolysis in myocardial infarction (TIMI) major and minor bleeding. Secondary end points were probable ST, myocardial infarction, cardiovascular death and the combined end point: major cardiac adverse event (MACE).

RESULTS

53% of patients presented with acute coronary syndrome (9% STEMI, 44% non-ST-elevation). HPR to ADP after 600 mg clopidogrel loading occurred in 30% of patients (73±19 U vs 28±11 U; p<0.001) and was treated by prasugrel or ticagrelor (73%), or clopidogrel (27%) reloading (22±12 U; p<0.001). HPR to ADP after prasugrel loading occurred in 2% of patients (82±26 U vs 19±10 U; p<0.001) and was treated with ticagrelor (34±15 U; p=0.02). HPR to AA occurred in 9% of patients with a significant higher proportion in patients with HPR to ADP (22% vs 4%, p<0.001) and was treated with aspirin reloading. Definite ST occurred in 0.09% of patients (n=1); probable ST, myocardial infarction, cardiovascular death and MACE occurred in 0.19% (n=2), 0.09% (n=1) and 1.8% (n=18) of patients. TIMI major and minor bleeding did not differ between patients without HPR and individualised patients (2.6% for both).

CONCLUSIONS

Individualisation of DAPT with MEA minimises early thrombotic events in an all-comers PCI population to an unreported degree without increasing bleeding. A randomised multicentre trial utilising MEA seems warranted.

TRIAL REGISTRATION NUMBER

http://www.clinicaltrials.gov; NCT01515345.

The clinical utility of Multiplate analyser measurement in platelet function testing following stroke and transient ischaemic attack

BACKGROUND

Platelet responsiveness to aspirin in people with cerebrovascular disease is poorly understood.

OBJECTIVES

To determine: (i) normal reference range, imprecision and reproducibility of the Multiplate instrument in healthy volunteers naive to aspirin; (ii) imprecision and reproducibility of the Multiplate instrument in acute stroke and transient ischaemic attack (TIA); (iii) the relationship between aspirin responsiveness and clinical outcome.

MATERIALS AND METHODS

We evaluated platelet function response to three agonists [Adenosine Diphosphate (ADP), Arachidonic Acid (AA), Collagen (Col)] using the Mulitplate platelet function analyser in a two-phase pilot study. In phase 1, we recruited healthy volunteers to determine the normal reference range and imprecision of the Multiplate instrument. In phase 2, we assessed platelet function in acute stroke or TIA patients presenting to hospital. These patients were bled within 24 h of presentation and between 12 and 24 h after ≥75 mg dose of Aspirin. Patients were followed up to 1 yr to assess mortality and recurrent cardiovascular event.

RESULTS

Overall, 29 healthy volunteers and 81 stroke/TIA patients were recruited. On assessing components of variance, Multiplate testing is reproducible and precise in volunteers and stroke/TIA patients. In stroke patients receiving aspirin, Bland-Altman plots show initial day 1 measurement provided a reliable measure of continuing response to aspirin at day 3. We defined one-third of patients as aspirin resistant [31.8% (95% CI: 22.1%-42.8%)] using cut off mean aggregation of ≥23.08% for AA and mean aggregation of ≥80.76% for ADP.

CONCLUSION

The Multiplate device gives reproducible, precise results in volunteers and stroke/TIA patients.

Effect of statin therapy on vaspin levels in type 2 diabetic patients

BACKGROUND

Statins are commonly used antihyperlipidemic agents, with anti-inflammatory and immunomodulatory properties that are thought to account for a significant portion of their ability to protect against atherosclerosis and cardiovascular disease. Vaspin, a visceral adipose tissue-derived serine protease inhibitor, is an emerging adipokine with important insulin-sensitizing, cardioprotective, and antiatherosclerotic properties in patients with diabetes. In this randomized controlled clinical trial, we evaluated the effect of statin therapy on vaspin levels in patients with type 2 diabetes mellitus.

METHODS

Patients were divided into two groups, ie, those receiving simvastatin (study group, n = 33), and those who did not (control group, n = 29). Patient data, blood biochemistry, and vaspin levels were recorded at the beginning of the study (baseline) and after 8 weeks (end of the study).

RESULTS

After 8 weeks of treatment, vaspin levels were increased in patients treated with simvastatin (504.58 ± 203.07 pg/mL at baseline versus 629.15 ± 68.39 pg/mL after 8 weeks, P < 0.01), but not in patients who were not treated with simvastatin (613.33 ± 357.53 pg/mL at baseline versus 582.37 ± 84.63 pg/mL after 8 weeks, P > 0.05). In addition, the lipid-lowering effect of simvastatin was reflected in a statistically significant reduction in total cholesterol in the study group (220.75 ± 55.66 mg/dL at baseline versus 201.90 ± 53.65 mg/dL after 8 weeks P < 0.01) but not in the control group (214.24 ± 47.2 mg/dL at baseline versus 215.72 ± 43.65 mg/dL after 8 weeks, P > 0.05) and in a statistically significant reduction in triglyceride levels in the study group (265.8 ± 210.41 mg/dL at baseline versus 223.03 ± 178.67 mg/dL after 8 weeks, P < 0.05) but not in the control group (225.44 ± 115.13 mg/dL at baseline versus 215.58 ± 110.2 mg/dL after 8 weeks, P > 0.05). Mean vaspin levels were significantly higher in the study group than in the control group.

CONCLUSION

These results indicate that statin therapy increases plasma vaspin levels in addition to having a lipid-lowering effect. This could be a mechanism underlying the pleiotropic effects seen with statins, including their cardioprotective and antiatherosclerotic effects.