Clotting and myocardial infarction: a cycle of insights

Association Between R353Q (rs6046) Polymorphism in Factor VII with Coronary Heart Disease

A number of studies have showed the relationship between R353Q (rs6046) polymorphism in factor VII gene and coronary heart disease (CHD). However, the results remain controversial due to the limitations of the research objects and small sample size of individual study. We conducted this meta-analysis to validate the association between R353Q (rs6046) polymorphism and the risk of CHD.The relevant data was collected up to March 25, 2019 from PubMed, Web of Science, CNKI, and Wanfang databases. We examined all eligible studies using the Newcastle-Ottawa Quality Assessment Scale (NOS). The odds ratio (OR) and its corresponding 95% confidence interval (CI) were adopted to evaluate the relationship between the R353Q (rs6046) polymorphism and CHD. Stata version 14.0 (Stata Corporation, USA) was used in all statistical tests.There were at least 28 eligible studies, including 14626 cases and 17994 controls, included in our meta-analysis. R353Q (rs6046) polymorphism was associated with the reduced risk of CHD in four genetic models: allele model (Q versus R: OR = 0.79, 95% CI: 0.69 to 0.90, P < 0.001, I² = 56.4%), homozygote (co-dominant) model (QQ versus RR: OR = 0.72, 95% CI = 0.58 to 0.92, P = 0.004, I² = 5.8%), heterozygote (co-dominant) model (RQ versus RR: OR = 0.71, 95% CI = 0.58 to 0.86, P = 0.001, I² = 75.4%), and dominant model (RQ+QQ versus RR: OR = 0.74, 95% CI = 0.63 to 0.865, P < 0.001, I² = 64.1%) excluding recessive model (QQ versus RR+RQ: OR = 0.86, 95% CI = 0.57 to 1.28, P = 0.447, I² = 51.6%).The results of the current meta-analysis suggested that R353Q (rs6046) polymorphism was associated with the reduced risk of CHD, especially in Asians.

Prothrombin G20210A (rs1799963) polymorphism increases myocardial infarction risk in an age-related manner: A systematic review and meta-analysis

G20210A polymorphism (rs1799963) within the prothrombin gene is associated with a higher circulation level of prothrombin, thus increasing the likelihood of developing myocardial infarction (MI). Opinions differ regarding the correlation between prothrombin G20210A genotype and MI risk, which prompted us to conduct a meta-analysis to determine this association. PubMed, EMBASE, Web of Science and CNKI were searched for pertinent reports. A total of 34 studies involving 14 611 MI cases and 84 358 controls were analyzed in this quantitative analysis. We found a statistically significant association between prothrombin G20210A polymorphism and MI in the allele model (A vs. G, OR = 1.43, 95%CI: 1.18–1.72), heterozygote model (GA vs. GG, OR = 1.41, 95%CI: 1.16–1.72) and dominant model (GA + AA vs. GG, OR = 1.41, 95%CI: 1.15–1.72). The association remains significant in Caucasians but not in non-Caucasians. Moreover, prothrombin G20210A polymorphism increases MI risk in an age-related manner. A further significant association was found in a subpopulation younger than 55 years (allele model, OR = 1.76, 95%CI: 1.32–2.35; heterozygote model, OR = 1.70, 95%CI: 1.24–2.33; dominant model, OR = 1.70, 95%CI: 1.24–2.34). Sensitivity analysis and publication bias analysis revealed stable and statistically robust results. Our meta-analysis demonstrated that prothrombin G20210A polymorphism may represent a risk factor for MI.

Hypercoagulability and the risk of myocardial infarction and ischemic stroke in young women

BACKGROUND

Myocardial infarction (MI) and ischemic stroke (IS) are acute forms of arterial thrombosis and share some, but not all, risk factors, indicating different pathophysiological mechanisms.

OBJECTIVE

This study aims to determine if hypercoagulability has a differential effect on the risk of MI and IS.

PATIENTS AND METHODS

We reviewed the results from the Risk of Arterial Thrombosis in Relation to Oral Contraceptives study, a population-based case-control study involving young women (< 50 years) with MI, non-cardioembolic IS and healthy controls. From these data, relative odds ratios (ORIS /ORMI ) and their corresponding confidence intervals for all prothrombotic factors that were studied in both subgroups were calculated.

RESULTS

Twenty-nine prothrombotic risk factors were identified as measures of hypercoagulability. Twenty-two of these risk factors (21/29, 72%) had a relative odds ratios > 1; for 12 (41%), it was > 2; and for 5 (17%), it was > 2.75. The five risk factors with the largest differences in associations were high levels of activated factor XI (FXI) and FXII, kallikrein, the presence of lupus anticoagulans, and a genetic variation in the FXIII gene.

CONCLUSION

In young women, prothrombotic factors are associated more with the risk of IS than with MI risk, suggesting a different role of hypercoagulability in the mechanism leading to these two diseases.

Reduced plasma fibrinolytic capacity as a potential risk factor for a first myocardial infarction in young men

Studies on the relationship between fibrinolysis and arterial thrombosis have been conflicting. Previously, we demonstrated that hypofibrinolysis, as measured by a plasma-based assay, increased the risk of venous thrombosis. The present study investigated increased clot lysis time (CLT) measured with the same assay as a risk factor for myocardial infarction in a case-control study including 421 men with a first myocardial infarction and 642 controls below 70 years. CLT was strongly associated with body-mass index, lipid levels, blood pressure and C-reactive protein. Overall, risk of myocardial infarction was 1.4-fold (95% confidence interval (CI) 1.0-1.9) increased for CLT in the fourth quartile (longest CLT) compared with the first quartile. After adjusting for cardiovascular risk factors this risk disappeared (OR 1.0, 95%CI 0.6-1.5). In men aged <50 years the association was pronounced (OR 3.2, 95%CI 1.5-6.7). After adjustment for cardiovascular risk factors the risk was nearly twofold increased (OR 1.8, 95%CI 0.7-4.8). In men aged > or = 50 years, no clear association between CLT and risk of myocardial infarction was found. Our study suggests that hypofibrinolysis increases the risk of a first myocardial infarction in young men, although the causality of this association remains to be determined.

Prevalence and risk factors for heart disease among males with hemophilia

There have been conflicting reports in the literature about the protective effect of hemophilia on the occurrence of ischemic heart disease (IHD). Circulatory disease has been reported as the second most common cause of death in persons with hemophilia in the United States. In addition to diabetes and hypertension, high levels of FVIII, as may occur during factor concentrate infusions, may increase IHD risk in this population. To estimate the prevalence of heart disease and examine factors associated with IHD and other heart diseases among persons with hemophilia, we analyzed data collected from the medical records of 3,422 males with hemophilia living in six U.S. states from 1993 to 1998. Heart disease cases were ascertained from among 2,075 persons who were hospitalized at least once during the 6-year period. Of these, 48 were diagnosed with IHD and 106, with other types of heart disease. The age-specific prevalence of IHD ranged from 0.05% in those under 30 years to 15.2% in those 60 years or older. Hospital discharge rates in males with hemophilia with IHD and other types of heart disease were lower compared to rates in age-matched U.S. males. In our cohort, as in the general population, IHD was independently associated with age, hypertension, diabetes, and hyperlipidemia. Other heart diseases were associated with HIV infection, hypertension, hemophilia B, and diabetes. In summary, persons with hemophilia have unique risk factors such as infusion of factor concentrates and infection with HIV that may predispose them to heart disease as their life expectancy increases.

The blood coagulation system as a molecular machine

The human blood coagulation system comprises a series of linked glycoproteins that upon activation induce the generation of downstream enzymes ultimately forming fibrin. This process is primarily important to arrest bleeding (hemostasis). Hemostasis is a typical example of a molecular machine, where the assembly of substrates, enzymes, protein cofactors and calcium ions on a phospholipid surface markedly accelerates the rate of coagulation. Excess, pathological, coagulation activity occurs in "thrombosis", the formation of an intravascular clot, which in the most dramatic form precipitates in the microvasculature as disseminated intravascular coagulation. Thrombosis occurs according to a biochemical machine model in the case of atherothrombosis on a ruptured atherosclerotic plaque, but may develop at a slower rate in venous thrombosis, illustrating that the coagulation machinery can act at different velocities. The separate coagulation enzymes are also important in other biological processes, including inflammation for which the rapid conversion of one coagulation factor by the other is not a prerequisite. The latter role of coagulation enzymes may be related to the old and probably maintained function of the coagulation machine in innate immunity.