Identifying Sex Dimorphism in Peripheral Artery Disease with Platelet Mapping

Demographic diversity in platelet function and response to antiplatelet therapy

Recent studies have highlighted the complexity of platelet biology, revealing their diverse roles beyond hemostasis. Pathological platelet activation is now recognized as a key contributor to thrombosis and inflammation that are both central to cardiovascular disease (CVD). Emerging research emphasizes the significant impact of demographic factors - such as age, sex, race, and ethnicity - on CVD risk and responses to antiplatelet therapies. These population-based differences, shaped by genetic and non-genetic factors, highlight the need for reevaluation of antiplatelet strategies. We address current knowledge and emphasize the pressing need for further research into platelet biology and cardiovascular outcomes across diverse populations. In this review we advocate for tailored therapeutic approaches in CVD based on the recent demographic-focused findings.

Evaluation of sex-based differences in below-the-knee plaque histology in patients who underwent amputation for chronic limb-threatening ischemia

Objective

With the growing incidence of peripheral arterial disease (PAD) and the historic under-representation of female patients in cardiovascular trials, a comprehensive evaluation of sex-based variances in PAD presentation and treatment outcomes is needed. This study aims to evaluate sex-based differences in the vessel wall characteristics of patients who underwent amputation owing to critical limb-threatening ischemia to optimize personalized treatment planning and aid in the selection of endovascular devices for PAD patients.

Methods

A total of 35 lower limbs were collected from 34 patients with end-stage PAD undergoing major amputation. We selected, harvested, and cross-sectioned at 3- to 4-mm intervals 163 diseased below-the-knee arterial segments resulting in 1260 arterial rings. Histological analyses were conducted on each individual ring and later summarized by arterial segment.

Results

Male and female patients were remarkably similar across multiple plaque characteristics, including degree of stenosis, calcification severity and localization, and atherosclerotic patterns. A significant sex-based difference was noted in the presence of luminal thrombus, which was more prevalent in females (38.7% vs 25.0%; P = .016). Histopathological differences were noted between popliteal and tibial lesions, with popliteal segments demonstrating increased chronic total occlusion presence and atherosclerosis, whereas severe calcification occurred more often in tibial segments. A sex-based evaluation of the popliteal segments showed increased calcification (60.71% vs 28.0%; P = .003) and atherosclerosis (96.4% vs 73.0%; P = .028) in males compared with females.

Conclusions

Differences in the degree of calcification, incidence of atherosclerosis, and presence of luminal thrombus may pose important clinical implications for antiplatelet and anticoagulation regimen choice and guide treatment options. Further studies are warranted to evaluate the impact of these differences on outcomes of endovascular procedures.

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.

The impact of sex on platelet responses to aspirin in patients with peripheral artery disease

Women with peripheral artery disease (PAD) have poorer limb salvage outcomes in spite of having lower risk factors for vascular disease than their male counterparts. Mono antiplatelet therapy with aspirin is the cornerstone of medical treatment for PAD to reduce the risk of arterial thrombosis, but platelets in women may have a variable response to this standard of care compared to men. Viscoelastic assays, such as thromboelastography with platelet mapping (TEG-PM), have been utilized to identify prothrombotic states and may provide insight into a patient's real-time coagulation profile and their response to specific antiplatelet medications. The aim of this prospective, observational study was to delineate the sex differences in platelet function using TEG-PM in patients with PAD on aspirin post-revascularization for PAD. All patients with PAD undergoing revascularization on aspirin monotherapy were prospectively enrolled between December 2020 and September 2023. The cohort was divided by sex, demographics, medications, procedure type, and outcomes were documented. Serial perioperative TEG-PM assays (1, 3, and 6 months) were performed up to 6 months postoperatively and platelet function was evaluated in both groups. Statistical analysis between women and men was performed to identify sex-specific differences in platelet function. Over the study period, a total of 303 patients were enrolled. Of this cohort, 149 patients met the study criteria and 266 samples were analyzed; 52 (34.89%) were women and 97 (65.11%) were men. In the platelet mapping assay, women showed significantly greater MAActF and MAAA, than men (16.66 vs. 14.94, p < .03 and 37.26 vs. 32.38, p < .01, respectively) indicating stronger thrombotic propensity. Additionally, platelet inhibition was significantly lower in women compared to men (52.95% vs. 61.65%, p < .05). In clinical outcomes reported as thrombotic events, women showed significantly higher occlusion in the area of intervention than men (4 vs. 1, p < .05). There is a growing awareness of the variations in the natural course, underlying mechanisms, and resulting outcomes of cardiovascular conditions, including PAD, in relation to sex. In this study, women did not achieve the same levels of platelet inhibition and displayed a procoagulant tendency in comparison to men when administered aspirin. Overall, aspirin monotherapy may be potentially sufficient for men, but women may require increased doses and/or additional antiplatelet medications to achieve an equivalent therapeutic effect.