Venous thromboembolism in patients with symptomatic atherosclerosis

Prevention of Pulmonary and Venous Thromboembolism Post Coronary Artery Bypass Graft Surgery - Literature Review

Objective

The current review evaluates recent literature on the different aspects of prophylaxis in postoperative pulmonary and venous thromboembolism and their main risk factors.

Methods

The literature survey was carried out based on the PubMed data using the keywords “coronary artery bypass graft” and “venous thromboembolism” as components of the search field title.

Results

Studies reported several risk factors for postoperative thromboembolism including advanced age, postoperative immobilization, type of thromboprophylaxis, obesity, and location of the surgery.

Conclusion

According to the studies, tailored prophylaxis could be easily adapted to decrease the intensity and duration of postoperative thromboembolism in a patient with several disorders and comorbidities, especially in cardiovascular disease.

Frequency, Predictors, and Impact of Combined Antiplatelet Therapy on Venous Thromboembolism in Patients With Symptomatic Atherosclerosis

BACKGROUND

Observational studies suggest that symptomatic atherosclerosis may be associated with risk of venous thromboembolism (VTE). Prior randomized studies have demonstrated a significant reduction in recurrent VTE with aspirin monotherapy. Whether VTE risk is associated with more severe symptomatic atherosclerosis and more intensive antiplatelet therapy reduces VTE risk beyond aspirin monotherapy is unknown.

METHODS

TRA2P-TIMI 50 (Thrombin Receptor Antagonist in Secondary Prevention of Atherothrombotic Ischemic Events-Thrombolysis in Myocardial Infarction) (vorapaxar) and PEGASUS-TIMI 54 (Prevention of Cardiovascular Events in Patients With Prior Heart Attack Using Ticagrelor Compared to Placebo on a Background of Aspirin-Thrombolysis in Myocardial Infarction 54) (ticagrelor) were blinded, randomized placebo-controlled trials of antiplatelet therapy for the prevention of ischemic events in stable patients with symptomatic atherosclerosis. Two blinded vascular specialists systematically identified symptomatic venous thromboembolic events in both trials.

RESULTS

Of 47 611 patients with stable vascular disease followed for 3 years in both studies there were 343 VTE events in 301 patients (Kaplan-Meier rate at 3 years, 0.9% for placebo). The risk of VTE was independently associated with age, body mass index, polyvascular disease, chronic obstructive pulmonary disease, and malignancy. The burden of atherosclerosis manifested as an increasing number of symptomatic vascular territories was associated with a graded increase in the 3-year rates of VTE (0.76% for 1, 1.53% for 2, and 2.45% for 3 territories). More intensive antiplatelet therapy (vorapaxar and ticagrelor pooled) significantly reduced the risk of VTE by 29% compared with background antiplatelet therapy, from 0.93% to 0.64% at 3 years (hazard ratio, 0.71; 95% confidence interval, 0.56-0.89; P=0.003).

CONCLUSIONS

The rate of VTE in patients with atherosclerosis is ≈0.3% per year while on treatment with ≥1 antiplatelet agent, with increased risk independently associated with the number of symptomatic vascular territories. More intensive antiplatelet therapy reduces the risk of VTE. These data suggest a relationship between atherosclerosis burden and VTE risk, and they support inclusion of VTE as a prospective end point in long-term secondary prevention trials evaluating the risks and benefits of antiplatelet therapies in patients with atherosclerosis.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01225562.

Proatherogenic oxidized low-density lipoprotein/β2-glycoprotein I complexes in arterial and venous disease

OxLDL/β2GPI complexes have been implicated in the initiation and progression of atherosclerosis and associated with disease severity and adverse outcomes. We investigate the significance of anti-oxLDL/β2GPI antibodies and oxLDL/β2GPI complexes in patients with arterial and idiopathic venous disease. A cohort of 61 arterial disease patients, 32 idiopathic venous disease patients, and 53 healthy controls was studied. Because statins influence oxLDL/β2GPI, these complexes were analyzed on subjects not taking statins. Arterial and venous groups expressed higher levels of IgG anti-oxLDL/β2GPI antibodies than controls without any other significant clinical association. OxLDL/β2GPI complexes were significantly elevated in arterial (0.69 U/mL, P = 0.004) and venous disease (0.54 U/mL, P = 0.025) than controls (0.39 U/mL). Among arterial diseases, oxLDL/β2GPI was 0.85 U/mL for carotid artery disease, 0.72 U/mL for peripheral artery disease, and 0.52 U/mL for abdominal aortic aneurysm. There was a significant association with male gender, age, hypertension, and history of thrombosis. Subjects with oxLDL/β2GPI above the median (0.25 U/mL) were more likely to have arterial (OR 4.5, P = 0.004) or venous disease (OR 4.1, P = 0.008). Multivariate regression indicated that males (P = 0.021), high cholesterol (P = 0.011), and carotid disease (P = 0.023) were significant predictors of oxLDL/β2GPI. The coexistence of oxLDL/β2GPI in arterial and venous disease may suggest a common oxidative mechanism that independently predicts carotid artery disease.

Alterations in platelet function during aging: clinical correlations with thromboinflammatory disease in older adults

Platelets have a dynamic functional repertoire that mediates hemostatic and inflammatory responses. Many of these functions are altered in older adults, promoting a prothrombotic, proinflammatory milieu and contributing to risk of adverse clinical events. Drawing primarily from human studies, this review summarizes important aspects of aging-related changes in platelets. The relationship between altered platelet functions and thrombotic and inflammatory disorders in older adults is highlighted. Established and developing antiplatelet therapies for the treatment of thrombotic and inflammatory disorders are also discussed in light of these data.

Haemostasis in chronic kidney disease

The coagulation system has gained much interest again as new anticoagulatory substances have been introduced into clinical practice. Especially patients with renal failure are likely candidates for such a therapy as they often experience significant comorbidity including cardiovascular diseases that require anticoagulation. Patients with renal failure on new anticoagulants have experienced excessive bleeding which can be related to a changed pharmacokinetic profile of the compounds. However, the coagulation system itself, even without any interference with coagulation modifying drugs, is already profoundly changed during renal failure. Coagulation disorders with either episodes of severe bleeding or thrombosis represent an important cause for the morbidity and mortality of such patients. The underlying reasons for these coagulation disorders involve the changed interaction of different components of the coagulation system such as the coagulation cascade, the platelets and the vessel wall in the metabolic conditions of renal failure. Recent work provides evidence that new factors such as microparticles (MPs) can influence the coagulation system in patients with renal insufficiency through their potent procoagulatory effects. Interestingly, MPs may also contain microRNAs thus inhibiting the function of platelets, resulting in bleeding episodes. This review comprises the findings on the complex pathophysiology of coagulation disorders including new factors such as MPs and microRNAs in patients with renal insufficiency.

Statin therapy and levels of hemostatic factors in a healthy population: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

HMG-CoA reductase inhibitors (statins) reduce the risk of venous thromboembolism (VTE) in healthy people. Statins reduce levels of inflammation biomarkers; however, the mechanism for the reduction in VTE risk is unknown.

AIM

In a large cohort of healthy people, we studied associations of statin use with plasma hemostatic factors related to VTE risk.

METHODS

Cross-sectional analyses were performed in the Multi-Ethnic Study of Atherosclerosis (MESA), a cohort study of 6814 healthy men and women aged 45-84 years, free of clinical cardiovascular disease at baseline; 1001 were using statins at baseline. Twenty-three warfarin users were excluded. Age, race and sex-adjusted mean hemostatic factor levels were compared between statin users and non-users, and multivariable linear regression models were used to assess associations of statin use with hemostatic factors, adjusted for age, race/ethnicity, education, income, aspirin use, hormone replacement therapy (in women), and major cardiovascular risk factors.

RESULTS

Participants using statins had lower adjusted levels of D-dimer (- 9%), C-reactive protein (- 21%) and factor VIII (- 3%) than non-users (P < 0.05). Homocysteine and von Willebrand factor levels were non-significantly lower with statin use. Higher fibrinogen (2%) and plasminogen activator inhibitor-1 (22%) levels were observed among statin users than among non-users (P < 0.05). Further adjustment for LDL and triglyceride levels did not attenuate the observed differences in these factors with statin use.

CONCLUSIONS

Findings of lower D-dimer, FVIII and C-reactive protein levels with statin use suggest hypotheses for mechanisms whereby statins might lower VTE risk. A prospective study or clinical trial linking these biochemical differences to VTE outcomes in statin users and non-users is warranted.

Oral anticoagulants in the management of venous thromboembolism

Despite advances in diagnosis, prevention, and management, venous thromboembolism (VTE) remains a common cause of morbidity and mortality. For decades, antithrombotic therapy for prevention and treatment of VTE was limited to parenteral agents related to heparin and oral vitamin K antagonists (VKAs). Both classes of anticoagulants are effective, but have limitations, including considerable variability in dose-response, narrow therapeutic margins between the risks of thrombosis and bleeding, and the need to monitor anticoagulation intensity. Over the past decade, the introduction of new oral anticoagulants that specifically inhibit coagulation factors IIa (thrombin) or Xa has changed practice in a variety of clinical situations, including VTE prophylaxis and treatment. In this Review, we outline the use of the novel oral anticoagulants apixaban, dabigatran, edoxaban, and rivaroxaban in the prevention and treatment of VTE, and discuss practical considerations for choosing the appropriate drug for each patient. Although the introduction of novel anticoagulant drugs is promising, selecting the optimum strategy for an individual patient requires an understanding of the specific circumstances associated with thrombus formation and the pharmacological properties of each agent.

Venous thromboembolism in patients with prior stroke

Patients with prior stroke are susceptible to venous thromboembolism (VTE). We studied patients with stroke in the Worcester VTE study of 2488 consecutive patients hospitalized with VTE. In all, 288 (11.6%) had a clinical history of stroke and 2200 (88.4%) did not. Patients with stroke were more likely to die inhospital (9.2% vs 4%) and within 30 days of VTE diagnosis (16.7% vs 6.9%) compared with patients without stroke (all P < .001). Recent immobilization (adjusted odds ratio [OR] 2.15; 95% confidence interval [CI] 1.15-4.09) and inferior vena cava (IVC) filter insertion (adjusted OR 2.1; 95% CI 1.15-3.83) were associated with a doubling of inhospital death. Recent immobilization (adjusted OR 1.84; 95% CI 1.19-2.83) and IVC filter insertion (adjusted OR 1.94; 95% CI 1.2-3.14) were associated with an increased risk of death within 30 days of VTE. In conclusion, patients with VTE and prior stroke were more than twice as likely to die while hospitalized and within 30 days of VTE diagnosis.

Venous thromboembolism: epidemiology and magnitude of the problem

Pulmonary embolism is the third most common cardiovascular disease after myocardial infarction and stroke. The death rate from pulmonary embolism exceeds the death rate from myocardial infarction, because myocardial infarction is much easier to detect and to treat. Among survivors of pulmonary embolism, chronic thromboembolic pulmonary hypertension occurs in 2-4 of every 100 patients. Post-thrombotic syndrome of the legs, characterized by chronic venous insufficiency, occurs in up to half of patients who suffer deep vein thrombosis or pulmonary embolism. We have effective pharmacological regimens using fixed low dose unfractionated or low molecular weight heparin to prevent venous thromboembolism among hospitalized patients. There remains the problem of low rates of utilization of pharmacological prophylaxis. The biggest change in our understanding of the epidemiology of venous thromboembolism is that we now believe that deep vein thrombosis and pulmonary embolism share similar risk factors and pathophysiology with atherothrombosis and coronary artery disease.

Venous thromboembolism in patients with diabetes mellitus

PURPOSE

The majority of epidemiological studies demonstrate an increased risk of venous thromboembolism among diabetic patients. Our aim was to compare clinical characteristics, prophylaxis, treatment, and outcomes of venous thromboembolism in patients with and without previously diagnosed diabetes.

METHODS

We studied diabetic patients in the population-based Worcester Venous Thromboembolism Study of 2488 consecutive patients with validated venous thromboembolism.

RESULTS

Of 2488 venous thromboembolism patients, 476 (19.1%) had a clinical history of diabetes. Thromboprophylaxis was omitted in more than one third of diabetic patients who had been hospitalized for non-venous-thromboembolism-related illness or had undergone major surgery within 3 months before diagnosis. Patients with diabetes were more likely than nondiabetic patients to have a complicated course after venous thromboembolism. Patients with diabetes were more likely than patients without diabetes to suffer recurrent deep vein thrombosis (14.9% vs 10.7%) and long-term major bleeding complications (16.4% vs 11.7%) (all P=.01). Diabetes was associated with a significant increase in the risk of recurrent deep vein thrombosis (adjusted odds ratio [AOR] 1.74; 95% confidence interval [CI], 1.21-2.51). Aspirin therapy at discharge (AOR 1.59; 95% CI, 1.1-2.3) and chronic kidney disease (AOR 2.19; 95% CI, 1.44-3.35) were independent predictors of long-term major bleeding.

CONCLUSION

Patients with diabetes who developed venous thromboembolism were more likely to suffer a complicated clinical course. Diabetes was an independent predictor of recurrent deep vein thrombosis. We observed a low rate of thromboprophylaxis in diabetic patients. Further studies should focus on venous thromboembolism prevention in this vulnerable population.