Evidence against hypercoagulability in coronary artery disease

A Journey with LGMD: From Protein Abnormalities to Patient Impact

The limb-girdle muscular dystrophies (LGMD) are a collection of genetic diseases united in their phenotypical expression of pelvic and shoulder area weakness and wasting. More than 30 subtypes have been identified, five dominant and 26 recessive. The increase in the characterization of new genotypes in the family of LGMDs further adds to the heterogeneity of the disease. Meanwhile, better understanding of the phenotype led to the reconsideration of the disease definition, which resulted in eight old subtypes to be no longer recognized officially as LGMD and five new diseases to be added to the LGMD family. The unique variabilities of LGMD stem from genetic mutations, which then lead to protein and ultimately muscle dysfunction. Herein, we review the LGMD pathway, starting with the genetic mutations that encode proteins involved in muscle maintenance and repair, and including the genotype–phenotype relationship of the disease, the epidemiology, disease progression, burden of illness, and emerging treatments.

Antithrombotic effect and mechanism of Rubus spp. Blackberry

The compounds of Rubus spp. Blackberry (RSB) were isolated and identified by a bioassay-guided method, and their antithrombotic effects and mechanism were investigated with the acute blood stasis rat model. The RSB extract was evaluated by activated partial thromboplastin time (APTT), thrombin time (TT), prothrombin time (PT), and fibrinogen (FIB) assays in vitro. Results indicated that RSB extract exhibited anticoagulant activity. In addition to compounds 1 and 6, the other compounds also exhibited anticoagulant activity in vitro. Therefore, the in vivo antithrombosis effects of RSB extract were investigated by measuring whole blood viscosity (WBV), plasma viscosity (PV), APTT, PT, TT, and FIB. Meanwhile, the levels of thromboxane B2 (TXB₂), 6-keto prostaglandin F1α (6-keto-PGF1α), endothelial nitric oxide synthase (eNOS) and ET-1 (endothelin-1) were measured. Results suggested that RSB extract had inhibitory effects on thrombus formation, and its antithrombotic effects were associated with the regulation of vascular endothelium active substance, activation of blood flow and an anticoagulation effect.

Antithrombotic Effect and Mechanism of Radix Paeoniae Rubra

The compounds of Radix Paeoniae Rubra (RPR) were isolated and identified by bioassay-guided method, and antithrombotic effects and mechanism were investigated by the acute blood stasis rat model. The RPR extract was evaluated by APTT, TT, PT, and FIB assays in vitro. Results indicated that RPR extract exhibited the anticoagulant activity. In order to find active compounds, six compounds were isolated and identified, and four compounds, paeoniflorin (Pae), pentagalloylglucose (Pen), albiflorin (Ali), and protocatechuic acid (Pro), exhibited the anticoagulant activity in vitro. Therefore, the antithrombosis effects of RPR extract and four active compounds were investigated in vivo by measuring whole blood viscosity (WBV), plasma viscosity (PV), APTT, PT, TT, and FIB. Meanwhile, the levels of TXB₂, 6-Keto-PGF_1α, eNOS, and ET-1 were detected. Results suggested that RPR extract and four active compounds had the inhibition effect on thrombus formation, and the antithrombotic effects were associated with the regulation of vascular endothelium active substance, activating blood flow and anticoagulation effect.

Association between Stable Coronary Artery Disease and In Vivo Thrombin Generation

Background. Thrombin has been implicated as a key molecule in atherosclerotic progression. Clinical evidence shows that thrombin generation is enhanced in atherosclerosis, but its role as a risk factor for coronary atherosclerotic burden has not been proven in coronary artery disease (CAD) stable patients. Objectives. To evaluate the association between TAT levels and homocysteine levels and the presence of coronary artery disease diagnosed by coronary angiography in patients with stable CAD. Methods and Results. We included 95 stable patients admitted to the Haemodynamics Department, including 63 patients with significant CAD and 32 patients without. We measured the thrombin-antithrombin complex (TAT) and homocysteine concentrations in all the patients. The CAD patients exhibited higher concentrations of TAT (40.76 μg/L versus 20.81 μg/L, p = 0.002) and homocysteine (11.36 μmol/L versus 8.81 μmol/L, p < 0.01) compared to the patients without significant CAD. Specifically, in patients with CAD+ the level of TAT level was associated with the severity of CAD being 36.17 ± 24.48 μg/L in the patients with bivascular obstruction and 42.77 ± 31.81 μg/L in trivascular coronary obstruction, p = 0.002. Conclusions. The level of in vivo thrombin generation, quantified as TAT complexes, is associated with the presence and severity of CAD assessed by coronary angiography in stable CAD patients.

Taoren-Honghua herb pair and its main components promoting blood circulation through influencing on hemorheology, plasma coagulation and platelet aggregation

ETHNOPHARMACOLOGICAL RELEVANCE

Persicae Semen (Taoren) and Carthami Flos (Honghua) used in pair which is named as Taoren-Honghua (TH) herb pair has been used in traditional Chinese medicine (TCM) for promoting blood circulation to dissipate blood stasis for many years in China.

AIM OF THE STUDY

This paper investigated the effects of TH and its main components amygdalin and hydroxysafflor yellow A (HSYA) on hemorheological disorders of blood stasis in rats.

MATERIALS AND METHODS

Rats were randomly divided into seven groups (control group, model group, TH group, amygdalin group, HSYA group, amygdalin+HSYA group, and aspirin group) with eight animals in each, whose gender was equally distributed throughout groups. All treatments were performed by gavage and administered seven times with an interval of 12h. After the fifth administration, the model rats except those in control group with blood stasis were established by being placed in ice-cold water during the interval between two injections of adrenaline hydrochloride (Adr); and blood samples were collected 30min after the last administration on the following day.

RESULTS

TH could significantly decrease whole blood viscosity (WBV), plasma viscosity (PV) and packed cell volume (PCV). It also significantly prolonged thrombin time (TT) and thromboplastin time (APTT), increased prothrombin time (PT) and lowered fibrinogen content (FIB). HSYA which significantly decreased WBV and PV had no effect on plasma coagulation parameters. Amygdalin could significantly decrease PV, prolong APTT and decrease FIB, showing few effects on WBV. TH and its main components amygdalin and HSYA could significantly reduce platelet aggregation and protect vascular endothelial cells. Based on the above results, amygdalin and HSYA were responsible for the main curative effects of TH and usually had synergetic effects, such as decreasing PV and platelet aggregation percentage.

CONCLUSIONS

The study may provide scientific information to further understanding of the mechanism(s) of TH and its main components in activating blood circulation to dissipate blood. It may also create valuable insight into the possible effects and utilization of TH and its components as a feasible alternative therapeutic agent for patients with hemorheological disorders.

Contemporary issues on clopidogrel therapy

In this paper, data from available studies regarding some contemporary issues on clopidogrel therapy are analyzed. In particular, the following clinical questions have been considered and addressed: (a) Is early clopidogrel treatment needed in patients with acute coronary syndromes treated medically or undergoing percutaneous coronary intervention (PCI)? (b) What is the optimal clopidogrel loading dose in patients undergoing PCI? (c) Is pre-treatment with clopidogrel before PCI needed, or can clopidogrel loading be given in the catheter laboratory before intervention, but after coronary anatomy is known? (d) What is the optimal clopidogrel strategy in patients on chronic clopidogrel therapy undergoing PCI? (e) Does the degree of clopidogrel response influence clinical outcome in patients undergoing PCI?

Randomized Trial of High Loading Dose of Clopidogrel for Reduction of Periprocedural Myocardial Infarction in Patients Undergoing Coronary Intervention

Background— Aggressive platelet inhibition is crucial to reduce myocardial injury and early cardiac events after coronary intervention. Although observational data have suggested that pretreatment with a high loading dose of clopidogrel may be more effective than a conventional dose, this hypothesis has never been tested in a randomized trial.

Methods and Results— A total of 255 patients scheduled to undergo percutaneous coronary intervention were randomized to a 600-mg (n=126) or 300-mg (n=129) loading regimen of clopidogrel given 4 to 8 hours before the procedure. Creatine kinase MB, troponin I, and myoglobin levels were measured at baseline and at 8 and 24 hours after intervention. The primary end point was the 30-day occurrence of death, myocardial infarction (MI), or target vessel revascularization. The primary end point occurred in 4% of patients in the high loading dose versus 12% of those in the conventional loading dose group ( P =0.041) and was due entirely to periprocedural MI. Peak values of all markers were significantly lower in patients treated with the 600-mg regimen ( P ≤0.038). Safety end points were similar in the 2 arms. At multivariable analysis, the high loading regimen was associated with a 50% risk reduction of MI (OR 0.48, 95% CI 0.15 to 0.97, P =0.044). An incremental benefit was observed in patients randomized to the 600-mg dose who were receiving statins, with an 80% risk reduction.

Conclusions— Pretreatment with a 600-mg loading dose of clopidogrel 4 to 8 hours before the procedure is safe and, as compared with the conventional 300-mg dose, significantly reduced periprocedural MI in patients undergoing percutaneous coronary intervention. These results may influence practice patterns with regard to antiplatelet therapy before percutaneous revascularization.

Prevalence and Risk of Thrombophilia Defects in Vascular Patients

This paper reviews the available data on the prevalence of thrombophilia defects in patients with peripheral vascular disease (PVD) and attempts to delineate the risk of failure of vascular intervention in these patients. The prevalence of thrombophilia in stable claudicants is 25% and increases to 40% in those requiring revascularisation, compared to only 11% in the control group. The overall prevalence of thrombophilia defects in patients with premature atherosclerosis appears to be between 15 and 30%. The prevalence in the typical cohort of patients with PVD appears to be similar. All these studies have recruited patients with symptoms significant enough to warrant intervention. The overall prevalence of thrombophilia calculated from these trials, therefore, may not be truly indicative of the general vascular population who may not even present primary or secondary healthcare. The risk of thrombotic occlusion following arterial revascularisation in patients with an identified thrombophilia defect appears to be almost three times that of patients with no evidence of a thrombophilia defect. The best management of these patients has not been determined and needs to be evaluated by prospective randomized trials.

Prothrombin Fragment 1+2 Is Associated With Carotid Intima-Media Thickness in Subjects Free of Clinical Cardiovascular Disease

Background and Purpose— Thrombin, a central enzyme in the clotting cascade, plays a role not only in thrombosis but also in the progression of atherosclerosis. We studied the relationship between prothrombin fragment 1+2 (F1+2), a specific marker of thrombin generation in vivo, and carotid intima-media thickness (IMT), an index of subclinical atherosclerosis.

Methods— We examined 181 asymptomatic middle-aged subjects (mean age 55.6 years, 76.7% men) free of overt clinical atherosclerotic disease. F1+2 was measured by enzyme-linked immunosorbent assay and IMT by duplex ultrasonography of carotid artery. Multiple linear regression analysis was used to assess the relationship between the 2 parameters.

Results— Compared with individuals in the lowest tertile of F1+2, those in the upper tertile (>0.55 nmol/L) showed significantly higher IMT ( P <0.01). In correlation analysis, a positive relationship was found between plasma F1+2 and carotid IMT. F1+2 also correlated positively with cholesterol ( P <0.008) and low-density lipoprotein cholesterol ( P <0.005), but not with blood pressure or body mass index. In the multivariate analysis, the association of F1+2 with carotid IMT remained significant ( P <0.001) after adjustment for age, sex, body mass index, systolic blood pressure, cholesterol, diabetes, and smoking.

Conclusions— In a population sample of adults without clinically overt atherosclerotic disease, the plasma levels of F1+2 were significantly associated with carotid IMT, suggesting a relationship between thrombin generation and the development atherosclerosis.

Markers of hypercoagulation and von Willebrand factor in postmenopausal women with unstable coronary artery disease. Discriminatory ability regarding unstable coronary artery disease and coronary atherosclerosis using receiver operating characteristics

OBJECTIVES

Many women with typical anginal chest pain have normal coronary angiograms. The pathogenetic mechanisms behind the chest pain in these patients are unknown but may be due to increased thrombogenicity. We evaluated markers of hypercoagulation and thrombosis in women with clinical signs of unstable coronary artery disease (CAD).

METHODS AND RESULTS

A total of 158 patients with unstable CAD and 101 controls were examined: 16% of the patients had normal vessels and 84% had coronary atherosclerosis at coronary angiography. Mean plasma concentrations of von Willebrand factor antigen, soluble fibrin (SF), thrombin-antithrombin complex and D-dimer were significantly higher, whereas there was no difference regarding prothrombin fragment 1+2 between patients and controls. Patients with coronary atherosclerosis had higher mean plasma levels for most variables compared with those with normal coronary vessels, although only significantly higher for SF. D-Dimer was significantly higher in patients with normal coronary vessels compared with the control group. Although multivariate analyses showed strong significant correlations of the haemostatic variables to the diagnosis of unstable CAD, receiver operating characteristics (ROC) revealed that none of the variables represented high diagnostic accuracy in separating patients with unstable CAD. Likewise, none of the variables was particularly good at identifying coronary atherosclerosis.

CONCLUSION

Our results are in favour of a hypercoagulable state in postmenopausal women with unstable CAD and coronary atherosclerosis, whereas this does not seem to be the case in patients with normal vessels. ROC revealed no variable to be particularly clinically useful in separating patients from controls or patients from those without coronary atherosclerosis.

Grape juice, but not orange juice or grapefruit juice, inhibits human platelet aggregation

Coronary artery disease is responsible for much mortality and morbidity around the world. Platelets are involved in atherosclerotic disease development and the reduction of platelet activity by medications reduces the incidence and severity of disease. Red wine and grapes contain polyphenolic compounds, including flavonoids, which can reduce platelet aggregation and have been associated with lower rates of cardiovascular disease. Citrus fruits contain different classes of polyphenolics that may not share the same properties. This study evaluated whether commercial grape, orange and grapefruit juices, taken daily, reduce ex vivo platelet activity. In a randomized cross-over design, ten healthy human subjects (ages 26-58 y, five of each gender) drank 5-7.5 mL/(kg. d) of purple grape juice, orange juice or grapefruit juice for 7-10 d each. Platelet aggregation (whole blood impedance aggregometry, Chronolog Model #590) at baseline was compared to results after consumption of each juice. Drinking purple grape juice for one week reduced the whole blood platelet aggregation response to 1 mg/L of collagen by 77% (from 17.9 +/- 2.3 to 4.0 +/- 6.8 ohms, P = 0.0002). Orange juice and grapefruit juice had no effect on platelet aggregation. The purple grape juice had approximately three times the total polyphenolic concentration of the citrus juices and was a potent platelet inhibitor in healthy subjects while the citrus juices showed no effect. The platelet inhibitory effect of the flavonoids in grape juice may decrease the risk of coronary thrombosis and myocardial infarction.

Prothrombin fragments F1+2, thrombin-antithrombin III complexes, fibrin monomers and fibrinogen in patients with coronary atherosclerosis

We determined the plasma levels of prothrombin fragment F1+2, thrombin-antithrombin III complexes (TAT), fibrin monomers (FM), D-dimers (DD) and fibrinogen in 57 patients with angiographically verified graded coronary artery disease (CAD) free of concomitant peripheral atherosclerosis, cerebrovascular disease or diabetes mellitus and a group of 21 apparently healthy controls. Blood was collected from the antecubital vein through atraumatic venipuncture prior to the angiographic procedure. Plasma levels of hemostatic markers were related to the presence and graded severity of CAD. The levels of prothrombin fragment F1+2 (1.74+/-0.11 vs. 1.0+/-0.07 nmol/l, P<0.001), FM (41.6+/-5.5 vs. 7.42+/-3.05 nmol/l, P<0.001), TAT (15.6+/-2.7 vs. 2.96+/-0.32 microg/l, P<0.001) and fibrinogen (3.64+/-1.3 vs. 3.08+/-0.33 g/l, P<0.01) were significantly higher in patients with CAD compared to controls, while there was no difference regarding the fibrinolytic system represented by DD (441.6+/-58.9 vs. 337.4+/-42.05 microg/l, n.s.). Within the CAD group, patients with extensive coronary atherosclerosis (> or =2 vessel disease) had significantly higher values for prothrombin fragment F1+2 (1.89 vs. 1.57 nmol/l, P = 0.04), FM (50.7 vs. 29.8 nmol/l, P = 0.03), and a trend to significance was noted for fibrinogen (3.9 vs. 3.3 g/l, P = 0.07) suggesting that blood coagulability was related to the severity of the disease and that hemostatic markers of thrombin activity represent a useful tool to identify patients with a latent hypercoagulable state with a higher susceptibility to sustain coronary thrombosis.

Thrombosis and Hemostasis in Cardiology: Review of Pathophysiology and Clinical Practice (Part I)

The adverse consequences of thrombosis are per haps nowhere more evident than in clinical cardiology. Throm bosis and hemostasis are primary issues in the management of patients with atrial fibrillation, prosthetic heart valves, severe left ventricular dysfunction, and coronary artery disease. Clini cal trials have defined a crucial role for anticoagulation with warfarin in patients with atrial fibrillation to reduce the inci dence of stroke. Anticoagulation with warfarin and aspirin in combination offers significant protection from systemic emboli in patients with mechanical prosthetic valves, without a sub stantial increased risk of hemorrhage. The risk of systemic emboli may also be reduced by anticoagulation in patients with severe left ventricular dysfunction. Disturbance of the normal balance of hemostasis is a major factor in the pathophysiology of coronary artery disease. Antiplatelet therapy, antithrombin agents, anticoagulants, and fibrinolytic agents have been used to prevent and treat acute coronary thrombosis and to prevent reocclusion following thrombolysis and interventional therapy. Guidelines are presented for antithrombotic therapy in the prac tice of clinical cardiology.