Sex differences in antiplatelet therapy: state-of-the art

The Impact of Sex on Antiplatelet and Anticoagulant Thromboprophylaxis in Patients With Peripheral Artery Disease Post-revascularization

OBJECTIVE

The aim of this prospective study was to (1) objectively quantify the impact of sex on platelet function in patients with peripheral artery disease (PAD) taking antiplatelet and anticoagulant medications and (2) to develop and test a personalized, iterative algorithm that personalizes thromboprophylaxis that incorporates platelet function testing.

BACKGROUND

Women with PAD have worse outcomes as compared with their male counterparts despite having lower risk factors. This health disparity may be mitigated by personalizing thromboprophylaxis regimens.

METHODS

Patients undergoing revascularization were enrolled. Serial thromboelastography (TEG) and TEG with platelet mapping (TEG-PM) were performed up to 6 months postoperatively to determine objective coagulation profiles. In a subset of patients, the Antiplatelet Coagulation Exactness (ACE) algorithm was implemented, where patients were iteratively evaluated with TEG and given antiplatelet medications to maintain platelet inhibition at >29%. Statistical analysis was performed using unpaired t test, analysis of variance, and Fisher exact test.

RESULTS

One hundred eighty-one patients met the study criteria. Fifty-eight (32%) patients were females and 123 (68%) were males. In the Aspirin cohort, females showed significantly greater clot strength as maximum amplitude - arachidonic acid (MA AA ) and significantly lower platelet inhibition than males: (37.26 vs 32.38, P <0.01) and (52.95% vs 61.65%, P <0.05), respectively. In the Clopidogrel cohort, females showed higher Maximum Amplitude - Adenosine Diphosphate (MA ADP ) (42.58 vs 40.35, P = not significant [NS]) compared with males. Females on dual antiplatelet therapy had higher MA ADP (39.74 vs 35.07, P =NS) and lower platelet inhibition (45.25% vs 54.99%, P= NS) than males. The incidence of thrombosis of the revascularized segment, defined as thrombotic event, was objectively identified on an arterial duplex. Women showed significantly higher thrombotic events than men (22.95% vs 10.57%, P< 0.05) on the same medication. In our pilot study, implementation of the ACE algorithm led to a significant decrease in the thrombosis rate (3%), including nonthrombotic events for females, versus the historic thrombotic rate (22%) from our institution.

CONCLUSIONS

Women with PAD exhibited higher platelet reactivity, clot strength, and reduced platelet inhibition in response to antiplatelet therapy. The use of the ACE algorithm to tailor antiplatelet medication in patients with PAD post-revascularization, resulted in a significant decrease in thrombotic event rates. This may serve as an opportune way to mitigate outcome sex-specific disparities caused by inadequate thromboprophylaxis in women.

Teaching gender medicine can enhance the quality of healthcare

Teaching gender and sex differences is fundamental in medical classes because it has a strong impact in reducing disparity in treatment, in defining effective and personalized therapies that respect the different physiology and pathophysiology of women. Furthermore, it is the prerequisite for the pharmacoequity.

Multi-Modal Venous ThromboembolicProphylaxis Aids in Risk Reduction Following Splenectomy in Female and Male Mice

INTRODUCTION

Splenectomy (SPLN) is associated with elevated risk of venous thromboembolic (VTE) disease. Enoxaparin (ENX) is a low-molecular-weight heparin agent used in VTE chemoprophylaxis. Early aspirin administration ameliorates postSPLN platelet hyperaggregability in male mice. Previous literature has excluded female mice, citing potential effects of estrogen on platelet count and activation as a reason. We hypothesized that multimodal therapy using aspirin and ENX would mitigate postoperative platelet aggregability in mice across sexes.

METHODS

Murine models of SPLN included both male and female mice. Treatment groups included placebo gavage, sham laparotomy, SPLN alone, SPLN and aspirin, SPLN and ENX, and SPLN with aspirin and ENX (n = 5 per group). Chemoprophylaxis dosing was initiated before SPLN. Mice were euthanized on post-operative day (POD) 1 or 3; platelet counts were obtained and blood samples were analyzed via electrical impedance aggregometry.

RESULTS

Females on POD 3 following SPLN demonstrated increased platelet count compared to female mice with no treatment intervention. Male and female mice demonstrated increased adenosine diphosphate (ADP)-induced platelet aggregability on POD 3 following SPLN compared to the placebo group. Treatment with aspirin and ENX decreased this post-SPLN platelet hyperaggregability in both sexes. Females demonstrated significantly higher ADP-mediated platelet aggregability in placebo, SPLN, and SPLN with aspirin and ENX when compared to males of identical treatment groups on POD 3.

CONCLUSIONS

Platelet hyperaggregability following SPLN is mediated primarily by ADP in both males and females, but higher relative aggregability is demonstrated in females. Early administration of dual-agent VTE chemoprophylaxis utilizing aspirin and ENX mitigates this hyperaggregability and may aid in VTE risk reduction across sexes.

Lipoprotein Metabolism, Dyslipidemia, and Lipid-Lowering Therapy in Women: A Comprehensive Review

Lipid-lowering therapy (LLT) is a cornerstone of atherosclerotic cardiovascular disease prevention. Although LLT might lead to different reductions in low-density lipoprotein cholesterol (LDL-C) levels in women and men, LLT diminishes cardiovascular risk equally effectively in both sexes. Despite similar LLT efficacy, the use of high-intensity statins, ezetimibe, and proprotein convertase subtilisin/kexin type 9 inhibitors is lower in women compared to men. Women achieve the guideline-recommended LDL-C levels less often than men. Greater cholesterol burden is particularly prominent in women with familial hypercholesterolemia. In clinical practice, women and men with dyslipidemia present with different cardiovascular risk profiles and disease manifestations. The concentrations of LDL-C, lipoprotein(a), and other blood lipids differ between women and men over a lifetime. Dissimilar levels of LLT target molecules partially result from sex-specific hormonal and genetic determinants of lipoprotein metabolism. Hence, to evaluate a potential need for sex-specific LLT, this comprehensive review (i) describes the impact of sex on lipoprotein metabolism and lipid profile, (ii) highlights sex differences in cardiovascular risk among patients with dyslipidemia, (iii) presents recent, up-to-date clinical trial and real-world data on LLT efficacy and safety in women, and (iv) discusses the diverse medical needs of women and men with dyslipidemia and increased cardiovascular risk.

Do platelets protect the heart against ischemia/reperfusion injury or exacerbate cardiac ischemia/reperfusion injury? The role of PDGF, VEGF, and PAF

BACKGROUND

Acute myocardial infarction (AMI) is one of the main causes of death. It is quite obvious that there is an urgent need to develop new approaches for treatment of AMI.

OBJECTIVE

This review analyzes data on the role of platelets in the regulation of cardiac tolerance to ischemia/reperfusion (I/R).

METHODS

It was performed a search of topical articles using PubMed databases.

FINDINGS

Platelets activated by a cholesterol-enriched diet, thrombin, and myocardial ischemia exacerbate I/R injury of the heart. The P2Y12 receptor antagonists, remote ischemic postconditioning and conditioning alter the properties of platelets. Platelets acquire the ability to increase cardiac tolerance to I/R. Platelet-derived growth factors (PDGFs) increase tolerance of cardiomyocytes and endothelial cells to I/R. PDGF receptors (PDGFRs) were found in cardiomyocytes and endothelial cells. PDGFs decrease infarct size and partially abrogate adverse postinfarction remodeling. Protein kinase C, phosphoinositide 3-kinase, and Akt involved in the cytoprotective effect of PDGFs. Vascular endothelial growth factor increased cardiac tolerance to I/R and alleviated adverse postinfarction remodeling. The platelet-activating factor (PAF) receptor inhibitors increase cardiac tolerance to I/R in vivo. PAF enhances cardiac tolerance to I/R in vitro. It is possible that PAF receptor inhibitors could protect the heart by blocking PAF receptor localized outside the heart. PAF protects the heart through activation of PAF receptor localized in cardiomyocytes or endothelial cells. Reactive oxygen species and kinases are involved in the cardioprotective effect of PAF.

CONCLUSION

Platelets play an important role in the regulation of cardiac tolerance to I/R.

Sex Differences in Cardiovascular Management: A Call for Better Acknowledgment-Part 1 Pharmacological Differences in Women and Men; How Relevant Are They?

BACKGROUND

Sex differences (SDs) in pharmacology of cardiovascular (CV) drugs have been described previously; however, paradoxically, there are scarce recommendations in therapy based on these differences. It is of utmost importance to identify whether these SDs determine a modified clinical response and the potential practical implications for this, to provide a base for personalized medicine.

AREA OF UNCERTAINTY

The aim of this article was to outline the most important pharmacological drivers of cardiovascular drugs that differ between women and men, along with their implications and challenges in clinical practice.

DATA SOURCES

A detailed assessment of English-written resources reflecting SDs impact in CV drug pharmacology was performed using PubMed and Embase databases.

RESULTS

Despite large variations in CV drug pharmacokinetics and pharmacodynamics in individuals, correcting for height, weight, surface area, and body composition compensate for most "sex-dependent" differences. In addition, individual, cultural, and social factors significantly impact disease management in women versus men. Gender-biased prescribing patterns and gender-dependent adherence to therapy also influence outcomes. The development of sex-specific guidelines requires that they should reflect the SDs implications for the management of a disease and that the evidence should be carefully evaluated as to whether there is an adequate representation of both sexes and whether sex-disaggregated data are reported.

CONCLUSIONS

Pharmacological drivers are under the influence of an impressive number of differences between women and men. However, to establish their significance in clinical practice, an adequate representation of women in studies and the reporting of distinct results is mandatory.

Association of sex and aspirin use with postoperative bleeding in patients with lower extremity long bone fractures

Objective

The perioperative management of patients on antiplatelet drugs is a rising challenge in orthopedic trauma because antiplatelet drugs are frequently encountered and carry an increased risk of hemorrhagic consequences. The study objective was to examine the effect of aspirin on bleeding outcomes for patients with lower extremity fractures.

Methods

This retrospective study included patients requiring surgical fixation of traumatic hip, femur, and tibia fractures from January 1, 2018, to March 1, 2020. Patients were excluded if they had a significant head injury, were on chronic anticoagulant therapy, or they did not receive venous thromboembolism chemoprophylaxis. Comparisons between aspirin users (patients on aspirin therapy preinjury) and non-aspirin users were examined using χ2 tests, Cochran-Mantel-Haenszel tests, and multivariate logistic regression. The primary outcome was an overt, actionable bleed (eg, blood transfusion for surgical site hemorrhage) within 24 hours postoperative.

Results

There were 864 patients with lower extremity long bone fractures and 24% were aspirin users. The incidence of postoperative bleeding was 8.8% and significantly differed for patients taking aspirin versus not (13.6% vs 7.3%, p=0.01). However, biological sex at birth (M/F) was a significant effect modifier (interaction p=0.04). Among women, there were significantly more postoperative bleeds for aspirin users (17.8% aspirin vs 7.4% no aspirin, adjusted OR (AOR): 2.48 (1.28-4.81), p=0.01). Among men, there were similar postoperative bleeding events by aspirin use (5.6% aspirin vs 7.2% no aspirin, AOR: 0.50 (0.14-1.82), p=0.30). Postoperative hemoglobin values <8 g/dL were more frequent among female aspirin users (21.5% aspirin vs 12.5% no aspirin, p=0.01), but this association was not observed in men (p=0.43).

Conclusion

Women taking aspirin who suffer lower extremity fractures have greater than twofold greater odds of a postoperative bleeding event. These findings suggest adequate perioperative planning to ensure blood availability, and increased awareness to monitor closely for hemorrhage in the 24-hour postoperative window for women taking aspirin preinjury.

Level of evidence

IV.

Low ambient temperature exposure increases the risk of ischemic stroke by promoting platelet activation

BACKGROUND

Accumulating epidemiological evidence suggests the association between low ambient temperature exposure and the risk of ischemic stroke, but the underlying mechanisms remain unclear.

OBJECTIVE

Given the crucial role of platelet activation and thrombosis in ischemic stroke, this study aims to investigate the effect of ambient temperature on platelet activation through multi-center clinical data in Tianjin as well as animal experiments.

METHODS

From 2018 to 2020, nearly 3000 ischemic stroke patients from three stroke centers in Tianjin were included in the analysis, among them the ADP induced platelet aggregation rate was available. Meteorological data from the same period had also been collected. After controlling for confounding factors, the generalized additive mixed model (GAMM) was used to evaluate the correlation between environmental temperature and platelet aggregation rate. In further animal experiments, platelet function assessments were conducted on mice from the cold exposure group and the normal temperature group, including platelet aggregation, spreading, and clot retraction. Additionally, tail bleeding and mesentery thrombosis were also tested to monitor hemostasis and thrombosis in vivo.

RESULT

A nonlinear "S" shaped relationship between outdoor temperature and platelet aggregation was found. Each 1 °C decrease of mean temperature was associated with an increase of 7.77 % (95 % CI: 2.06 % - 13.48 %) in platelet aggregation. The ambient temperature is not related to other platelet parameters. Subgroup analysis found that males, people aged ≥65 years, and hypertensive individuals are more susceptible to temperature changes. Furthermore, animal experiments demonstrated that the increased CIRBP levels and subsequent activation of p-AKT/p-ERK may be one of the reasons for cold exposure induced platelets activation.

CONCLUSION

Both clinical data and basic research support that low ambient temperature exposure has the potential to increase platelet activation. These results provide a basis for understanding the potential mechanism of temperature variations on the pathogenesis of cerebrovascular diseases.

The Cellular and Protein Arms of Coagulation in Diabetes: Established and Potential Targets for the Reduction of Thrombotic Risk

Diabetes is a metabolic condition with a rising global prevalence and is characterised by abnormally high blood glucose levels. Cardiovascular disease (CVD) accounts for the majority of deaths in diabetes and, despite improvements in therapy, mortality and hospitalisations in this cohort remain disproportionally higher compared to individuals with normal glucose metabolism. One mechanism for increased CVD risk is enhanced thrombosis potential, due to altered function of the cellular and acellular arms of coagulation. Different mechanisms have been identified that mediate disordered blood clot formation and breakdown in diabetes, including dysglycaemia, insulin resistance, and metabolic co-morbidities. Collectively, these induce platelet/endothelial dysfunction and impair the fibrinolytic process, thus creating a prothrombotic milieu. Despite these abnormalities, current antithrombotic therapies are largely similar in diabetes compared to those without this condition, which explains the high proportion of patients experiencing treatment failure while also displaying an increased risk of bleeding events. In this narrative review, we aimed to summarise the physiological functioning of haemostasis followed by the pathological effects of diabetes mellitus on platelets and the fibrin network. Moreover, we carefully reviewed the literature to describe the current and future therapeutic targets to lower the thrombosis risk and improve vascular outcomes in diabetes.

Gender differences in efficacy and safety of antiplatelet strategies for acute coronary syndromes

INTRODUCTION

Dual antiplatelet therapy (DAPT) represents the cornerstone of secondary prevention in patients presenting with acute coronary syndrome (ACS) and undergoing percutaneous coronary intervention. Despite its undisputed efficacy in reducing thrombotic events, DAPT increases the risk of bleeding, which is associated with higher morbidity and mortality. Novel antiplatelet strategies (i.e. in terms of timing, selection of drugs and their combinations, and modulation strategies) have been tested in randomized trials, suggesting the utility of tailored approaches in selected populations (i.e. patients at high bleeding or ischemic risk). It remains uncertain whether the effect of these strategies is influenced by sex.

AREAS COVERED

This narrative review provides an overview of available evidence surrounding sex differences in the efficacy and safety of antiplatelet strategies for ACS and analyzes the potential reasons behind these findings. Relevant content was searched for in PubMed.

EXPERT OPINION

Significant differences between women and men exist in terms of clinical presentation, pharmacotherapies, interventional management, and prognosis of ACS. However, these observations do not appear to be attributed to different pharmacodynamic effects of antiplatelet therapies between women and men. Unfortunately, a critical issue depends on women being often underrepresented in clinical trials, leading to a substantial lack of sex-specific evidence.