Faculty Bibliography

BACKGROUND:Coronavirus disease 2019 (COVID-19) is associated with macro- and micro-thromboses, which are triggered by endothelial cell activation, coagulopathy, and uncontrolled inflammatory response. Conventional antithrombotic agents are under assessment in dozens of randomized controlled trials (RCTs) in patients with COVID-19, with preliminary results not demonstrating benefit in several studies. OBJECTIVES/OBJECTIVE:Given the possibility that more novel agents with antithrombotic effects may have a potential utility for management of patients with COVID-19, we assessed ongoing RCTs including these agents with their potential mechanism of action in this population. METHODS:We searched clinicaltrials.gov and the World Health Organization International Clinical Trials Registry Platform to identify RCTs of novel antithrombotic agents in patients with COVID-19. RESULTS:Based on a systematic literature search, 27 RCTs with 10 novel antithrombotic agents (including nafamostat, dociparstat, rNAPc2, and defibrotide) were identified. The results from these trials have not been disseminated yet. The studied drugs in the ongoing or completed RCTs include agents affecting the coagulation cascade, drugs affecting endothelial activation, and mixed acting agents. Their postulated antithrombotic mechanisms of action and their potential impact on patient management are summarized. CONCLUSION/CONCLUSIONS:Some novel antithrombotic agents have pleiotropic anti-inflammatory and antiviral effects, which may help reduce the viral load or fibrosis, and improve oxygenation. Results from ongoing RCTs will elucidate their actual role in the management of patients with COVID-19.

OBJECTIVE:Heightened inflammation, dysregulated immunity, and thrombotic events are characteristic of hospitalized COVID-19 patients. Given that platelets are key regulators of thrombosis, inflammation, and immunity they represent prime candidates as mediators of COVID-19-associated pathogenesis. The objective of this study was to understand the contribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to the platelet phenotype via phenotypic (activation, aggregation) and transcriptomic characterization. APPROACH AND RESULTS/UNASSIGNED:In a cohort of 3915 hospitalized COVID-19 patients, we analyzed blood platelet indices collected at hospital admission. Following adjustment for demographics, clinical risk factors, medication, and biomarkers of inflammation and thrombosis, we find platelet count, size, and immaturity are associated with increased critical illness and all-cause mortality. Bone marrow, lung tissue, and blood from COVID-19 patients revealed the presence of SARS-CoV-2 virions in megakaryocytes and platelets. Characterization of COVID-19 platelets found them to be hyperreactive (increased aggregation, and expression of P-selectin and CD40) and to have a distinct transcriptomic profile characteristic of prothrombotic large and immature platelets. In vitro mechanistic studies highlight that the interaction of SARS-CoV-2 with megakaryocytes alters the platelet transcriptome, and its effects are distinct from the coronavirus responsible for the common cold (CoV-OC43). CONCLUSIONS:Platelet count, size, and maturity associate with increased critical illness and all-cause mortality among hospitalized COVID-19 patients. Profiling tissues and blood from COVID-19 patients revealed that SARS-CoV-2 virions enter megakaryocytes and platelets and associate with alterations to the platelet transcriptome and activation profile.

BACKGROUND AND AIMS/OBJECTIVE:Obesity is an independent risk factor for atherosclerotic cardiovascular disease (CVD), and platelet hyperactivation in obesity may contribute to this association. Olive oil consumption is associated with lower cardiovascular disease (CVD) risk in the general population. However, little is known for individuals with obesity. We investigated whether olive oil intake is associated with platelet activation in obesity. METHODS AND RESULTS/RESULTS:. Olive oil intake was stratified into <1 time/week (n = 21), 1-3 times/week (n = 18), ≥4 times/week (n = 24). Strata did not differ by age, BMI or platelet count. Unstimulated P-selectin expression did not differ by olive oil consumption. Subjects with more frequent olive oil intake exhibited lower P-selectin expression on submaximal thrombin exposure. CONCLUSIONS:More frequent olive oil intake is associated with reduced thrombin-induced platelet activation in obesity.

Myocardial injury after noncardiac surgery is defined by elevated postoperative cardiac troponin concentrations that exceed the 99th percentile of the upper reference limit of the assay and are attributable to a presumed ischemic mechanism, with or without concomitant symptoms or signs. Myocardial injury after noncardiac surgery occurs in ≈20% of patients who have major inpatient surgery, and most are asymptomatic. Myocardial injury after noncardiac surgery is independently and strongly associated with both short-term and long-term mortality, even in the absence of clinical symptoms, electrocardiographic changes, or imaging evidence of myocardial ischemia consistent with myocardial infarction. Consequently, surveillance of myocardial injury after noncardiac surgery is warranted in patients at high risk for perioperative cardiovascular complications. This scientific statement provides diagnostic criteria and reviews the epidemiology, pathophysiology, and prognosis of myocardial injury after noncardiac surgery. This scientific statement also presents surveillance strategies and treatment approaches.

BACKGROUND:Among patients with diabetes and chronic coronary disease, it is unclear if invasive management improves outcomes when added to medical therapy. METHODS:The ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches) trials (ie, ISCHEMIA and ISCHEMIA-Chronic Kidney Disease) randomized chronic coronary disease patients to an invasive (medical therapy + angiography and revascularization if feasible) or a conservative approach (medical therapy alone with revascularization if medical therapy failed). Cohorts were combined after no trial-specific effects were observed. Diabetes was defined by history, hemoglobin A1c ≥6.5%, or use of glucose-lowering medication. The primary outcome was all-cause death or myocardial infarction (MI). Heterogeneity of effect of invasive management on death or MI was evaluated using a Bayesian approach to protect against random high or low estimates of treatment effect for patients with versus without diabetes and for diabetes subgroups of clinical (female sex and insulin use) and anatomic features (coronary artery disease severity or left ventricular function). RESULTS:<0.001). At median 3.1-year follow-up the adjusted event-free survival was 0.54 (95% bootstrapped CI, 0.48-0.60) and 0.66 (95% bootstrapped CI, 0.61-0.71) for patients with diabetes versus without diabetes, respectively, with a 12% (95% bootstrapped CI, 4%-20%) absolute decrease in event-free survival among participants with diabetes. Female and male patients with insulin-treated diabetes had an adjusted event-free survival of 0.52 (95% bootstrapped CI, 0.42-0.56) and 0.49 (95% bootstrapped CI, 0.42-0.56), respectively. There was no difference in death or MI between strategies for patients with diabetes versus without diabetes, or for clinical (female sex or insulin use) or anatomic features (coronary artery disease severity or left ventricular function) of patients with diabetes. CONCLUSIONS:Despite higher risk for death or MI, chronic coronary disease patients with diabetes did not derive incremental benefit from routine invasive management compared with initial medical therapy alone. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01471522.

Background : In addition to their role in thrombosis and hemostasis, platelets are key mediators of inflammation and altered immunity. Circulating monocyte-platelet aggregates (MPA) represent the crossroads between thrombosis and inflammation and may represent a therapeutic target. While antiplatelet therapy (APT) reduces platelet activity and thrombosis, its effect on MPA is uncertain. Aims : To analyze the effect of APT on MPA in vitro. Methods : The effect of different platelet-activating agonists (thromboxane analog U-46619, ADP, PAR4, collagen, and epinephrine) on MPA formation in whole blood (WB) was measured via flow cytometry. Agonist-stimulated WB was incubated in the presence of inhibitors against P-selectin, PSGL-1, PAR1 (ML161), P2Y12 (AZD1283), GPIIb/IIIa (eptifibatide), acetyl salicylic acid (ASA), and dipyridamole and assessed for MPA formation. RNA-Seq data sets of monocytes incubated with healthy platelet releasates (PR) were used to identify platelet-induced upregulation of monocyte transcripts and were validated by RT-qPCR in monocyte-PR co-incubation assays in the presence of APT. Results : Circulating MPA are increased in prothrombotic and inflammatory diseases including the most recent COVID-19. Monocytes aggregated to platelets have more CD40 and tissue factor expression than monocytes not aggregated to platelets ( P < 0.05 for each comparison). As expected, targeting P-selectin (85.4% reduction) and PSGL-1 (88.2% reduction) had the greatest attenuation of MPA. Among platelet inhibitors, P2Y12 inhibition was most effective in lowering MPA formation (30.7% reduction) (figure 1). Flow cytometry analysis of MPA. Incubation of monocytes with platelet releasate induced upregulation of inflammatory mRNA transcripts suppressor of cytokine signaling 3 ( SOCS3 ) and o ncostatin m ( OSM ). Following pretreatment of platelets with APT, both GPIIb/IIIa and P2Y12 inhibition was associated with lower expression of SOCS3 and OSM (figure 2) . SOCS3 and OSM in monocytes incubated with APT-treated PR. Conclusions : Circulating MPA represent a crossroad of platelet and monocyte activation. We show that APT is associated with both reduced MPA formation and platelet-induced monocyte activation

Background : Patients with Human Immunodeficiency Virus (HIV) exhibit an activated platelet phenotype and an increased risk of Cardiovascular Disease (CVD). Aims : We conducted a randomized controlled trial to investigate the efficacy of aspirin and clopidogrel (two anti-platelet medications commonly used to prevent CVD) to reduce platelet activation and platelet effector cell properties in HIV patients. Methods : Fifty five HIV positive patients (mean age 53.5 +/- 7.8 years, 42.6% female, mean CD4+ T-cell count 665.6 cells/m 3 ), were enrolled to receive clopidogrel ( n = 22, 75 mg/d), aspirin ( n = 22, 81 mg/d), or no-treatment ( n = 11) for 14-days. Platelet aggregation and platelet receptor expression of p-selectin and pac-1 was assessed at baseline and day 14. To assess the impact of platelet inhibition on the endothelium ( in vitro ), platelets isolated from 6 patients (2/ group) at baseline and follow-up were incubated in HUVECs and proinflammatory HUVEC gene expression was assessed (Nanostring, 594 transcripts). Results : Aspirin treatment significantly reduced platelet aggregation to arachidonic acid (AA) (84% to 31%, P < 0.01) while clopidogrel reduced platelet aggregation to adenosine diphosphate (ADP) (85% to 41%, P < 0.001), confirming study drug compliance. Clopidogrel treatment decreased platelet p-selectin (-5.9%, P = 0.04), p-selectin plus thrombin (-40.8%, P = 0.03), pac-1 expression (-8%, P = 0.02), and pac-1 plus ADP (-24.0%, P = 0.03) and AA (-24.0%, P < 0.01). In contrast, aspirin did not affect p-selectin or pac-1 expression. When compared to no-treatment, HIV patients on clopidogrel exhibited a reduction in the composite pro-inflammatory transcript expression of platelet treated HUVECS (Log2 Fold DELTA -0.07 +/- 0.58 vs. -0.12 +/- 0.53, P < 0.001) while aspirin treated platelets upregulated HUVEC transcript expression (Log2 Fold DELTA-0.07 +/- 0.58 vs. 0.19 +/- 0.59, P < 0.001). Conclusions : Clopidogrel, but not aspirin, reduced platelet activation and HUVEC pro-inflammatory gene expression. Our results suggest that clopidogrel as opposed to aspirin may be preferential to reduce CV risk in HIV; however, larger clinical trials are needed to expand upon these findings

Background : Cancer and peripheral artery disease (PAD) share common risk factors and are frequently coprevalent. Platelets are culprits in the pathogenesis of PAD and mediators of arterial cardiovascular events. The association between platelet activity and cardiovascular events in patients with versus without cancer is uncertain. Aims : To investigate if cancer history is associated with platelet activity and incident cardiovascular events in a cohort of patients with PAD. Methods : 289 patients with PAD undergoing lower extremity revascularization enrolled in the Platelet Activity and Cardiovascular Events (PACE) study were followed longitudinally for a median of 18 months. Prior to revascularization, patients had platelet activity measured via light transmission aggregometry in response to ADP, collagen, epinephrine, and serotonin. The primary clinical outcome was myocardial infarction (MI). Other endpoints were MI/stroke and major adverse cardiovascular event (MACE; MI/stroke/death). Results : 64 patients (22.1%) reported a cancer history, 10 (15.6%) with metastatic and 10 (15.6%) with active cancer. Patients with (versus without) cancer history were older, less often Hispanic, and less frequently current smokers ( P < 0.05 for each). There was no difference in prevalent diabetes, coronary artery disease, hypertension, or antiplatelet therapy between groups. Platelet aggregation in response to submaximal ADP (0.4 muM, 1.0 muM), collagen (0.2 mug/ml, 1.0 ug/ml), and serotonin (10 muM) was higher in patients with versus without cancer history. Consistently, patients with cancer history experienced more incident MI (18.8% vs. 7.6%, P = 0.02), MI/stroke (25.0% vs. 9.3%, P = 0.002), and MACE (35.9% vs. 22.2%, P = 0.04). After adjustment for age, sex, race/ethnicity, smoking, diabetes, prior stroke, CAD, revascularization procedure, and antiplatelet therapy, patients with cancer history were at higher hazard for MI, MI/stroke, and MACE (Figure). The association between cancer and thrombotic events was most apparent in patients with metastatic and active cancer (Figure). Conclusions : In patients with PAD, cancer history was associated with increased platelet aggregation and risk for arterial thrombotic events

BACKGROUND:Older adults undergoing noncardiac surgery have a high risk of major adverse cardiovascular events (MACE). This study aims to estimate the magnitude of increased perioperative risk, and examine national trends in perioperative MACE following in-hospital noncardiac surgery in older adults compared to middle-aged adults. DESIGN/METHODS:Time-series analysis of retrospective longitudinal data. SETTING/METHODS:The United States Agency for Healthcare Research and Quality National Inpatient Sample (NIS). PARTICIPANTS/METHODS:Hospitalizations for major noncardiac surgery among adults age ≥45 years between January 2004 and December 2014. MEASUREMENTS/METHODS:Inpatient perioperative MACE was defined as a composite of in-hospital death, myocardial infarction (MI), and ischemic stroke. In hospital death was determined from the NIS discharge disposition. MI and ischemic stroke were defined by International Classification of Diseases, Ninth Revision codes. RESULTS:Of an estimated 55,349,978 surgical hospitalizations, 26,423,039 (47.7%) were for adults age 45-64, 14,231,386 (25.7%) age 65-74, 10,621,029 (19.2%) age 75-84 years, and 4,074,523 (7.4%) age ≥85 years. MACE occurred in 1,601,022 surgical hospitalizations (2.9%). Adults 65-74 (2.8%; aOR 1.16, 95% CI 1.14-1.17), 75-84 years (4.5%; aOR 1.30, 95% CI 1.28-1.32), and ≥85 years (6.9%; aOR 1.55, 95% CI 1.52-1.57) had greater risk of MACE than those 45-64 years (1.7%). From 2004 to 2014, MACE declined among adults 65-74 (3.1-2.5%, p < 0.001), 75-85 years (4.9-3.9%, p < 0.001), and ≥85 years (7.7-6.1%, p < 0.001), but was unchanged for adults age 45-64. Declines in MACE were driven by decreased MI and mortality despite increased stroke. CONCLUSION/CONCLUSIONS:Older adults accounted for half of hospitalizations, but experienced the majority of MACE. Older adults had greater adjusted odds of MACE than younger individuals. The proportion of perioperative MACE declined over time, despite increases in ischemic stroke. These data highlight risks of noncardiac surgery in older adults that warrant increased attention to improve perioperative outcomes.