Cardiorespiratory Fitness Is Associated with Decreased Platelet Reactivity.

PURPOSE: Platelets are key mediators in cardiovascular disease (CVD). Low cardiorespiratory fitness (CRF) is a risk factor for CVD. The purpose of our study was to assess if CRF associates with platelet function. METHODS: Platelet assays and cardiopulmonary exercise testing were conducted in the Framingham Heart Study (n = 3,014). Linear mixed effects models estimated associations between CRF (assessed by peak oxygen uptake [VO2]), and multiple platelet reactivity assays. Models were adjusted for multiple medications, risk factors, relatedness and prevalent CVD. RESULTS: Nineteen associations passed the significance threshold in the fully adjusted models, all indicating higher CRF associated with decreased platelet reactivity. Significant traits spanned multiple platelet agonists. Strongest associations were observed in Multiplate whole blood testing after TRAP-6 (e.g., velocity, beta = -0.563, 95% CI [-0.735,-0.391], p = 1.38E-10), ADP (e.g., velocity, beta = -0.514, 95% CI [-0.681,-0348], p = 1.41E-09), collagen (e.g., velocity, beta = -0.387, 95% CI [-0.549,-0.224], p = 3.01E-06), ristocetin (e.g., AUC, beta = -0.365, 95% CI [-0.522,-0.208], p = 5.17E-06) and arachidonic acid stimulation of platelets (e.g., velocity, beta = -0.298, 95% CI [-0.435,-0.162], p = 3.39E-04), and light transmission aggregometry (LTA) after ristocetin stimulation (e.g., max aggregation, beta = -0.362, 95% CI [-0.540,-0.184], p = 6.64E-05). One trait passed significance threshold in the aspirin sub-sample (LTA ristocetin primary slope, beta = -0.733, 95% CI [-1.134,-0.333], p = 3.30E-04), and another in a model including von Willebrand Factor levels as a covariate (U46619, a thromboxane receptor mimetic, AUC in the Optimul assay, beta = -0.36, 95%CI [-0.551,-0.168], p = 2.35E-04). No strong interactions were observed between the associations and sex, age or body mass index in formal interaction analyses. CONCLUSIONS: Our findings build on past work that shows CRF to be associated with reduced CVD by suggesting decreased platelet reactivity may play a mechanistic role. We found significant associations with multiple platelet agonists, indicating higher CRF may globally inhibit platelets; however, given multiple strong associations after TRAP-6 and ADP stimulation, PAR-1 and purinergic signaling may be most heavily involved. This is notable since each of these receptor pathways are tied to anti-coagulant (DOACs/thrombin inhibitors) and anti-platelet therapies (P2Y12/PAR1/PAR4 inhibitors) for CVD prevention.

The association between platelet reactivity and lipoprotein levels in Framingham Heart Study participants.

BACKGROUND: Hypertriglyceridemia is an independent risk factor for major adverse cardiovascular events, though the mechanisms linking triglycerides and platelet function with thrombosis, remain elusive. The aim of this study was to assess the association between platelet function and triglyceride levels. METHODS: We included participants from the Framingham Heart Study Third Generation cohort, OMNI, and New Offspring Spouse cohort who attended the third examination cycle (2016-2019). Eligible participants were categorized into four triglyceride subgroups. RESULTS: The study comprised a total of 1897 (55.53 %) participants with normal TG levels; 883 (25.85 %) participants with high-normal TGs; 378 (11.07 %) with borderline high TGs; and 258 (7.55 %) participants with hypertriglyceridemia. After adjusting for age, sex, alcohol consumption, aspirin, statin and P2Y12 inhibitors, the levels of ADP-induced platelet aggregation were inversely associated with total cholesterol levels (P < 0.0001). Platelet disaggregation was associated with low-density lipoprotein and high-density lipoprotein cholesterol levels (P < 0.0001). Lastly, in a shear-stress chamber assay mimicking arterial flow velocities, TG levels in the normal-high group were associated with increased levels of collagen-dependent thrombogenicity (ß = 24.16, SE = 6.65, P < 0.0001). CONCLUSION: Triglyceride levels are associated with altered platelet activation and aggregation. Furthermore, increased platelet-driven thrombogenicity is directly associated with triglyceride levels after adjusting for medications and other covariates.

Serotonin-Affecting Antidepressant Use in Relation to Platelet Reactivity.

Depression is an independent risk factor of cardiovascular disease morbidity. Serotonin is a key neurotransmitter in depressive pathology, contained within platelets, and is a weak activator of platelets. Our study assessed the link between platelet reactivity traits, depression, and antidepressant (AD) use in a large population sample. Our study was conducted in the Framingham Heart Study (n = 3,140), and AD use (n = 563) and aspirin use (n = 681) were noted. Depression was measured using the Center for Epidemiological Studies-Depression (CES-D) survey. Platelet reactivity traits were measured across multiple agonists using five distinct assays. We utilized a linear mixed effects model to test associations between platelet traits and depression, adjusting for age, sex, aspirin use, and AD use. Similarly, we analyzed trait associations with any AD use, serotonin-affecting ADs, and norepinephrine-affecting ADs, respectively. There were strong associations with reduced platelet function and AD use, particularly with serotonin-affecting medications. This included lower Optimul epinephrine maximal aggregation (P = 4.87E-13), higher U46619 half maximal effective concentration (P = 9.09E-11), lower light transmission aggregometry (LTA) adenosine diphosphate (ADP) final aggregation (P = 1.03E-05), and higher LTA ADP disaggregation (P = 2.28E-05). We found similar associations with serotonin-affecting ADs in an aspirin-taking subset of our sample. There were no significant associations between platelet traits and depression. In the largest study yet of AD use and platelet function we show that antidepressants, particularly serotonin-affecting ADs, inhibit platelets. We did not find evidence that depressive symptomatology in the absence of medication is associated with altered platelet function. Our results are consistent with AD use leading to platelet serotonin depletions, decreased stability of platelet aggregates, and overall decreased aggregation to multiple agonists, which may be a mechanism by which ADs increase risk of bleeding and decrease risk of thrombosis.