Aspirin Resistance: Cardiovascular Risk Game Changer

Aspirin 15cH has Different Effects on Morphology and Function of Lipopolysaccharide-Challenged RAW 264.7 Macrophages In Vitro Compared to a Pharmacological Dose of Aspirin

INTRODUCTION

 Aspirin is one of the most commonly used drugs worldwide. It is known to present antipyretic, anti-inflammatory and anti-thrombotic actions, making it extremely useful in a wide range of clinical contexts. Interestingly, homeopathically prepared Aspirin 15cH has been found to have a pro-thrombotic effect in rats, raising the hypothesis that Aspirin 15cH could also modulate the activity of inflammatory cells in different pathological processes.

OBJECTIVE

 Our objective was to assess what effect Aspirin 15cH has on RAW 264.7 macrophages in vitro.

METHODS

 The effects of Aspirin 15cH on biochemical and morphological activities of lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages were evaluated. These effects were compared with unchallenged macrophages (negative control), untreated LPS-stimulated macrophages, macrophages treated with succussed water (vehicle control), or aspirin 200 µg/mL (pharmacological inhibitor of LPS activity). Cell morphology (adhered cell area and cytoskeleton arrangements), cell viability, toll-like receptor-4 (TLR-4) expression, and the production of nitric oxide, cytokines and intracellular reactive oxygen species were assessed.

RESULTS

 Aspirin 15cH reduced the number of cells expressing TLR-4 on the surface (p = 0.03) and induced a "columnar" morphology of macrophage pseudopods, indicating changes in cytoskeleton arrangement. When cells were treated with both Aspirin 15cH and LPS, cell morphology became heterogeneous, suggesting that sub-populations of cells had differing sensitivities to LPS or Aspirin 15cH. Exposure of the cells to LPS alone, succussed water or aspirin 200 µg/mL produced effects consistent with the literature.

CONCLUSION

 Aspirin 15cH, aspirin 200 µg/mL, LPS and succussed water appear to act as independent stimuli able to induce different patterns of macrophage response. Aspirin 15cH induced changes suggestive of M2 polarization of the macrophages (i.e., toward a wound healing or tissue repair, rather than inflammatory, phenotype). These preliminary findings need to be confirmed in further specific studies.

Factors Associated with Aspirin Resistance in Hong Kong Chinese Patients with Stable Coronary Heart Disease Using the Multiplate® Analyzer and Serum Thromboxane B2

Introduction: Aspirin resistance may be associated with various conditions. We measured serum thromboxane B2 (TXB2) and platelet function using the Multiplate® Analyzer with arachidonic acid (ASPI) in patients on long term aspirin therapy to identify aspirin resistance and associated factors. Materials and Methods: Chinese patients with stable coronary heart disease had samples for serum TXB2 and ASPI measurement taken before and 1 h after taking a morning dose of 80 mg aspirin. Results: In 266 patients with mean age 66.6 ± 10.7 years, 17% were female and 55% were current or previous smokers. TXB2 and ASPI measurements were significantly higher before the dose than at 1 h post dose, with 46% of subjects having high ASPI values (AUC > 300 AU*min) pre dose compared with 27% at 1 h post dose. TXB2 and ASPI measures of platelet aggregation showed weak correlations, which were only significant before the dose (r = 0.219, p = 0.001). Increased ASPI measurements were associated with white blood cell (WBC) count, haematocrit, platelet count and heart rate at 24 h post dose but only with WBC count, smoking history and heart rate at 1 h post dose. Diabetes was not associated with reduced platelet response to aspirin. The WBC count associated with aspirin resistance was over 6.55 × 109/L by receiver operating characteristic analysis. Conclusions: The antiplatelet response to aspirin was reduced in a large proportion of patients. Patients with higher WBC count within the normal range appear to be at increased risk of aspirin resistance. Higher or more frequent doses of aspirin may be needed in many patients.

Association of PeriOPerative Aspirin-ResisTance and CardioVascular Outcome (POPART- CVO) - a prospective non-interventional cohort study

OBJECTIVES

New onset of aspirin-resistance during surgery, known as perioperative aspirin-resistance, is observed in up to 30% of vascular surgery patients and is associated with post-OP myocardial damage; questioning aspirin effectiveness towards perioperative cardiovascular events. The objective of this study was to prospectively evaluate whether perioperative aspirin-resistance in vascular surgery is associated with adverse cardiovascular outcome.

DESIGN AND METHODS

Based on a sample size calculation, 194 adult elective vascular or endovascular surgery patients receiving aspirin were analyzed in this prospective, single-centered, non-interventional cohort study. Platelet function was measured before surgery, one hour after incision, four hours postoperatively, and on the morning of the first and second postoperative days using the Multiplate® analyzer. The primary outcome was Myocardial Injury after Non-Cardiac Surgery (MINS). Secondary outcomes included major bleeding, admission to intensive care unit, length of hospital stay, and Major Adverse Cardiac and Cerebrovascular Events. Subgroup analyses were performed for patients with different cardiovascular risk and for patients who underwent endovascular surgery.

RESULTS

Perioperative aspirin-resistance was observed in 27.8% of patients but was not associated with MINS (27.8% vs. 32.1%, aspirin-resistance vs. no aspirin-resistance, OR 0.812, 95% CI [0.406;1.624], p=.555) or with any of the secondary endpoints (all p>.05). In nine of the ten subgroup analyses, aspirin-resistance was not associated with a difference in MINS rate. However, in patients with a low cardiovascular risk profile (RCRI 0-2), MINS occurred more frequently in patients without aspirin-resistance (p=.049).

CONCLUSIONS

We confirmed previous reports demonstrating that perioperative aspirin-resistance is frequent in patients undergoing vascular or endovascular surgery. However, in patients who continue aspirin throughout the perioperative period, aspirin-resistance is a phenomenon, that does not appear to be related to MINS. Measuring perioperative platelet function using the Multiplate® analyzer with the intention to identify and potentially prevent or treat perioperative aspirin-resistance seems to be dispensable.

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.

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.

The Association between Multi-Vessel Coronary Artery Disease and High On-Aspirin Platelet Reactivity

BACKGROUND

Multi-vessel coronary artery disease (MV-CAD) is correlated with worse clinical outcomes compared with single-vessel CAD (SV-CAD). The aim of this study was to evaluate the association between MV-CAD and high on-aspirin platelet reactivity (HAPR) in patients with stable CAD treated with aspirin.

METHODS

The current study is an analysis of prospectively enrolled randomly selected patients with known stable CAD, who were taking aspirin (75-100 mg qd) regularly for at least one month, and had undergone coronary angiography at least 3 months prior to the enrollment to the study.

EXCLUSION CRITERIA

acute coronary syndrome at the time of platelet function testing, active malignancy, acute infection, active inflammatory/rheumatic disease, major surgery in the past 6 months, chronic liver failure, treatment with oral anticoagulation, non-adherence with Aspirin and thrombocytopenia (<100 K/micl). Blood was drawn from the participants and sent for platelet function testing (VerifyNow, Instrumentation Laboratory Company, Bedford, Massachusetts, United States). MV-CAD was defined as >50% stenosis in ≥2 separate major coronary territories per coronary angiography. HAPR was defined as aspirin reaction units (ARU) >550.

RESULTS

Overall, 507 patients were analyzed; age 66.7 ± 11.2, 17.9% women, 223 (44%) had MV-CAD. The rate of HAPR was significantly higher among patients with MV-CAD vs. SV-CAD (14.8% vs. 3.5%, p < 0.001, respectively). Furthermore, a "dose response"-like association was found between the number of stenotic coronary arteries and the rate of HAPR (3.5%, 13.5 and 17.3% for SV-CAD, 2-vessel and 3-vessel disease, respectively). In a multivariate analysis adjusted for potential confounders, MV-CAD was found to be a strong independent predictor of HAPR [OR = 1.8 (95%CI: 1.05-4.7), p = 0.014].

CONCLUSIONS

A significant association between MV-CAD and HAPR was found. Additional studies designed to investigate the mechanisms of HAPR and different therapeutic options for this subset of patients are warranted.

[Serum concentration of phospholipase A2 and platelet aggregation during hyperbaric oxygen therapy in patients with ischemic heart disease]

Hyperbaric oxygenation (HBO) for correction of platelet haemostasis disorders in coronary heart disease (CHD) is reasonable due to the associated hypocoagulation. However, in practice, the baseline state of platelet activity is not considered when prescribing HBO therapy. Available publications lack information on structural changes in the platelet membrane associated with the of phospholipase A2 (PLA2) activity, and on the HBO effect on the various steps of hemostasis.

OBJECTIVE

To study changes in serum PLA2 concentration and its relation to platelet aggregation activity during HBO in patients with stable CHD.

MATERIAL AND METHODS

We examined 42 patients with stable angina FC II-III, 27 received antiplatelet therapy (Cardiomagnyl 75 mg: acetylsalicylic acid + magnesium hydroxide), and 15 patients did not. All patients received a 10-day course of HBO at 1.2 atmosphere mode for 40 min. Platelet hemostasis and serum PLA2 concentration were evaluated. Platelet aggregation was tested using Biola LA-230-2 aggregation analyzer (Biola Scientific, Russia). The platelets count and mean platelet volume (MPV) were determined on a Mindray BS-3200 hematology analyzer (Mindray, China). PLA2 levels were determined by enzyme immunoassay using Model 680 microplate reader (Bio-Rad, USA). Residual platelet reactivity was evaluated by 5.0 ADP-induced aggregation.

RESULTS

Assessment of the HBO effect on the functional state of platelets depending on their aggregation activity and the therapy taken showed a significant increase in spontaneous aggregation and ADP-induced aggregation at inducer concentration of 1.0 μM (p=0.049) in patients with baseline hyperaggregation taking Cardiomagnyl after HBO. No significant changes in PLA2 concentration were observed. At the same time, patients with baseline hyperaggregation who did not take antiplatelet agents had no changes in platelet aggregation activity and a decreased serum PLA2. In patients with baseline normal aggregation receiving an antiplatelet drug, a course of HBO had no effect on platelet aggregation activity and PLA2 level. In patients with baseline normal aggregation who did not take antiplatelet agents, a course of HBO resulted in significant decrease in PLA2 levels and no changes in platelet aggregation activity. In patients with low aggregation activity (hypoaggregation) who took antiplatelet agents, a significant increase in spontaneous aggregation and no change of serum PLA2 after an HBO course was observed.

CONCLUSION

The study showed a divergent response to the hyperbaric oxygen, depending on the antiplatelet therapy and the background aggregation.