Excesso de fator VIII em doente com síndroma coronária aguda

Factor VIII is a clotting factor that plays a crucial role in the coagulation cascade. Above‐normal levels are found in 11% of the general adult population. Various studies have established a causal association between elevated factor VIII and venous thrombosis; some studies also suggest a relation with arterial thrombosis, particularly myocardial infarction and stroke.We report the case of a 36‐year‐old man with obesity, smoking and dyslipidemia as cardiovascular risk factors and a history of acute myocardial infarction at age 26. He was admitted to the coronary care unit with a diagnosis of ST‐elevation myocardial infarction. Coronary angiography showed a thrombus in the distal segment of the first obtuse marginal artery, which was causing the obstruction. The thrombus was aspirated but there was no reflow. A coagulation study revealed elevated factor VIII; other parameters were normal.Even though this patient presented several cardiovascular risk factors, we highlight the need for more studies on the effect of elevated factor VIII on thrombus formation leading to acute coronary syndrome. Another important question is the use of oral anticoagulation in these patients as an integral part of the management of acute coronary syndrome.     

Raised factor VIII is associated with coronary thrombotic events

Coagulation is triggered during the onset of myocardial infarction, resulting in vascular occlusion. However, a causal role for individual haemostatic factors in the development of thrombotic occlusion is not established. Three cases (all relatively young women) are reported of raised factor VIII associated with myocardial infarction. Two patients presented acutely with myocardial infarction at a relatively young age with no preceding history of angina. The other patient had had venous thrombosis when young and activated protein C resistance (APCR), without the presence of factor V Leiden. A functional relation exists between APCR and factor VIII; therefore, raised factor VIII may contribute to APCR and the increased thrombotic risk in patients without factor V Leiden. Factor VIII is an important risk factor for atherothrombotic events, including sudden death, in patients with vascular disease. These cases support the association of raised factor VIII with acute thrombotic events, even in patients without significant underlying atheromatous disease.

Keywords: factor VIII;  thrombosis;  myocardial infarction;  activated protein C resistance     

Coronary artery disease in severe haemophilia

It has been suggested that the coagulation defect in haemophilia A protects these patients from coronary artery disease. We report two patients with severe haemophilia, who each had severe atheroma localised to the coronary arteries. Both patients had received only small amounts of factor VIII concentrates in their lifetime because of various social reasons. In one case death resulted from myocardial infarction secondary to an occlusive thrombus in a coronary artery. The implications of these findings to the pathogenesis of vascular disease are discussed.     

Coronary artery disease in severe haemophilia.

It has been suggested that the coagulation defect in haemophilia A protects these patients from coronary artery disease. We report two patients with severe haemophilia, who each had severe atheroma localised to the coronary arteries. Both patients had received only small amounts of factor VIII concentrates in their lifetime because of various social reasons. In one case death resulted from myocardial infarction secondary to an occlusive thrombus in a coronary artery. The implications of these findings to the pathogenesis of vascular disease are discussed.     

Myocardial infarction in Beh?et's disease

A case of myocardial infarction in a 23-year old male patient with Beh?et's disease is reported. The infarction occurred 4 years after the onset of the disease, which had been marked by recurrent venous thrombosis. Coronary arteriography showed stenosis of the anterior interventricular artery and occlusion of the first diagonal artery; the other coronary vessels were normal. A search for vascular risk factors, including haemostasis, was undertaken, yielding only moderate cigarette-smoking. About 10 cases of myocardial infarction associated with Beh?et's disease have been reported. They concerned young, usually male subjects. Infarction usually occurred late in the course of the disease, and vascular risk factors were seldom elicited. The leukocytoclastic vasculitis of Beh?et's disease alone may be responsible for stenosis, thrombosis and false arterial aneurysms, as shown by anatomical studies. The physiopathological mechanisms involved (reduction of endothelial or systemic fibrinolytic activity, rise in fibrinogen and factor VIII) are still unclear; we believe that these abnormalities are inconstant. Beh?et's disease may be regarded as a possible cause of myocardial infarction in young subjects.     

Coexistence of factor V Leiden and primary antiphospholipid syndrome: a patient with recurrent myocardial infarctions and thrombocytopenia

Increased thrombin generation associated with resistance to activated protein C makes the latter a likely candidate for an increased risk of acute coronary events. Activated protein C resistance (factor V Leiden) on its own, however, appears to have no significant effect in this regard. We describe a case of recurrent myocardial infarction caused by coronary thrombosis in a patient with persistent thrombocytopenia who was found to have a coexistence of heterozygous factor V Leiden and primary antiphospholipid syndrome. Since both thrombophilic disorders interfere with the protein C anticoagulant system, the simultaneous existence of inherited and acquired resistance against activated protein C could account for an increased thrombophilia with manifestation in the coronary arteries. This case suggests that evaluation of patients who present with recurrent acute coronary events should also consider these coagulation defects.     

Thrombosis and Fibrinolysis in Acute Myocardial Infarction

The development of coronary thrombosis in response to rupture of atherosclerotic plaques is the primary determinant of the evolution of stable atherosclerotic coronary disease to unstable ischemic syndromes and acute myocardial infarction. Activation of the tissue factor pathway of coagulation and adhesion of platelets are critical events in the initiation of thrombosis. However, subsequently, other factors may determine the extent of thrombosis by modulating the intensity of procoagulant and fibrinolytic activity. Marked procoagulant activity, attenuation of physiologic fibrinolytic activity, or both appear to be risk factors for myocardial infarction. The results of recent studies have provided considerable insight into potential mechanisms for thrombosis in response to rupture of atherosclerotic plaque and have identified potential novel antithrombotic interventions to inhibit the progression of coronary thrombosis.     

Myocardial infarction and thrombophilia: Do not miss the right diagnosis!

Protein C deficiency is a coagulation cascade disorder often resulting in venous thromboembolic events but is also a possible contributor to arterial thrombosis. To date, approximately ten cases of myocardial infarction (MI) due to protein C deficiency have been reported in the literature. However, affirming this mechanism requires ruling out the most common causes of MI, i.e. the rupture or erosion of an atherosclerotic plaque. Intravascular imaging of coronary arteries can be of help to identify angiographically undetected atherosclerosis. We report a case of an ST-segment elevation myocardial infarction (STEMI) in a young man with apparent evidence of arterial thrombosis resulting from protein C deficiency and heterozygous factor Leiden mutation which was contradicted by intravascular imaging demonstrating atherosclerosis.     

Coexistence of factor V Leiden and primary antiphospholipid syndrome: a patient with recurrent myocardial infarctions and thrombocytopenia

Increased thrombin generation associated with resistance to activated protein C makes the latter a likely candidate for an increased risk of acute coronary events. Activated protein C resistance (factorV Leiden) on its own, however, appears to have no significant effect in this regard. We describe a case of recurrent myocardial infarction caused by coronary thrombosis in a patient with persistent thrombocytopenia who was found to have a coexistence of heterozygous factor V Leiden and primary antiphospholipid syndrome. Since both thrombophilic disorders interfere with the protein C anticoagulant system, the simultaneous existence of inherited and acquired resistance against activated protein C could account for an increased thrombophilia with manifestation in the coronary arteries. This case suggests that evaluation of patients who present with recurrent acute coronary events should also consider these coagulation defects.     

Hormone Therapies and Vascular Outcomes: Who is at Risk?

Postmenopausal hormone replacement therapy (HRT), such as estrogen with a progestin (E+P), is associated with an increased risk of myocardial infarction (MI), stroke, and venous thrombosis. Subgroups of susceptible women for these clinical outcomes have not been clearly identified, although women with a prior history of venous thrombosis and women with factor V Leiden are at higher risk of venous thrombosis on HRT than others. Effects of HRT on atherosclerosis, coagulation, and inflammation have been investigated, and might improve our understanding of the pathogenesis of this drug effect. In 2 trials E+P did not alter the progression of coronary atherosclerosis, while in a third trial unopposed estradiol retarded atherosclerosis progression in the carotid arteries. HRT is associated with an increase in high-sensitivity C-reactive protein (CRP), an inflammation marker associated with arterial disease risk, and an increase in activated protein C resistance, the biochemical defect associated with factor V Leiden. Given recent data, the only current indication for E+P is the short-term treatment of symptoms of estrogen deficiency, such as hot flashes. Testing for coagulation disorders or inflammatory factors, such as factor V Leiden or CRP, for use in decision-making about HRT use would be premature in unselected patients. Further research is needed to identify pathophysiological mechanisms of vascular harm from these hormones.     

A case report of recurrent vascular access thrombosis in a hemodialysis patient reveals combined acquired and inherited thrombophilia

Vascular access thrombosis represents a serious and unfortunately common problem in hemodialysis patients. Usually, but not always, this complication can be attributed to low access blood flow. However, there are some patients who experience thrombosis despite a well functioning vascular access. We describe the case of a 31-year-old Caucasian male, who was hemodialyzed via an arteriovenous fistula for two years due to Alport's syndrome. During this time period he had two episodes of vascular access thrombosis that destroyed two arteriovenous fistulas. Both fistulas were functioning well and the thrombosis events took place in days between the hemodialysis sessions. Thrombophilia was suspected and the relative investigation revealed high levels of factor VIII procoagulant, which is frequent in hemodialysis patients, and resistance to activated protein C. Polymerase chain reaction detected that the patient was heterozygous for factor V Leiden, which is quite common in general population. Thereafter, a new arteriovenous fistula was formed and the patient started oral anticoagulation therapy with warfarin. Now, three years after the last arteriovenous fistula formation, the patient is hemodialyzed without vascular access problems. In conclusion, evaluation of the coagulation cascade in hemodialysis patients with recurrent vascular access thrombosis is necessary.     

In vivo and in vitro effects of thrombin and plasmin on human factor VIII (AHF).

The relationship between factor VIII (AHF) procoagulant activity and factor VIII-related antigen were examined in patients with disseminated intravascular coagulation (DIC), pulmonary embolism (PE), and coronary artery disease with or without myocardial infarction (MI). It was found that 13 of 13 patients with DIC, 17 of 17 patients with PE, and 10 of 12 patients with MI possessed a significantly elevated factor VIII-related antigen to factor VIII activity ratio (VIII-ratio). The VIII-ratio returned to normal in each of 2 patients with DIC and 1 paitent with PE after treatment with heparin, heparin and alpha-amino-caproic acid, and heparin and coumadin respectively. In contrast, the VIII-ratio was slightly elevated only in 1 of 15 patients with coronary artery insufficiency without MI. In in vitro studies, after treatment of plasma with thrombin or plasmin, factor VIII activity was lost, whereas the amount of factor VIII-related antigen remained the same or was even increased when measured by agarose quantitative immunoelectrophoresis. These observations have led us to conclude that an elevated VIII-ratio is a very sensitive indicator of intravascular coagulation.     

Venous thrombosis of the upper extremity: effect of blood group and coagulation factor levels on risk

Venous thrombosis of the upper extremity is a rare form of thrombosis, accounting for around 4% of all venous thromboses, and for which only a few risk factors are known. This case‐control study investigated the effect of coagulation factors on risk of venous thrombosis of the upper extremity. Patients with venous thrombosis of the arm and partner controls were selected from the Multiple Environmental and Genetic Assessment study, a large population‐based case‐control study. Participants with a malignancy were excluded. Odds ratios (OR) were estimated for elevated levels of factor II, VII, VIII, IX, X, XI, von Willebrand Factor (VWF), and fibrinogen, low levels of protein C, protein S, and antithrombin, and for blood group non‐O. Substantially increased risks of venous thrombosis of the upper extremity were found for patients with high levels (above 90th percentile versus below) of factor VIII (OR: 4·2, 95% confidence interval (CI): 2·2–7·9), VWF (OR: 4·0, 95% CI: 2·1–7·8), fibrinogen (OR: 2·9, 95% CI, 1·5–5·7), and for blood group non‐O compared to O (OR: 2·1, 95% CI, 1·3–3·6). The other factors were not associated with an increased risk. Elevated levels of several procoagulant factors are associated with a strongly increased risk of venous thrombosis of the upper extremity.     

Tissue factor: A key molecule in hemostatic and nonhemostatic systems

Tissue factor (also known as tissue thromboplastin or CD142) is the protein that activates the blood clotting system by binding to, and activating, the plasma serine protease, factor VIIa, following vascular injury. Because of its essential role in hemostasis, tissue factor plays a role in pathology associated with hemostasis, triggering the coagulation system in many thrombotic diseases and the coagulopathies associated with sepsis and other forms of disseminated intravascular coagulation. Recent research has also implicated tissue factor in a variety of nonhemostatic roles, including cell signaling, inflammation, vasculogenesis, and tumor growth and metastasis. This review focuses on both the well-known roles of tissue factor in hemostasis and thrombosis and the newer concepts of tissue-factor biology including how it functions as a signaling receptor and the possible role of blood-borne tissue factor in thrombosis.     

Changes in coagulation factors following acute myocardial infarction in man.

The whole blood clotting time, plasma fibrinogen and individual coagulation factors II, V, VII, VIII, IX, X, XI, and XII were serially measured in 14 patients over a 10-day period following acute myocardial infarction. A further six patients with similar symptoms but without evidence of myocardial infarction were also studied. The whole blood clotting time was significantly shorter within the first 24 h after infarction than on subsequent days. There were significant increases in the levels of fibrinogen and of factors VIII, IX, and XI and a significant decrease in factor XII in the patients who had sustained a myocardial infarction. The patients without myocardial infarction had no significant change in any of the coagulation factors measured.     

Functional Property of von Willebrand Factor Under Flowing Blood

von Willebrand factor (vWF) is produced in megakaryocytes and endothelial cells, is stored in the alpha-granule of platelets and in the Weibel-Palade body of endothelial cells, and is present in plasma and vascular subendothelium. This huge protein with a unique multimeric structure plays a pivotal role in both hemostasis and pathological intravascular thrombosis, in which vWF contributes to both platelet adhesion/aggregation and blood coagulation through its multiple adhesive functions for the platelet membrane receptors, glycoprotein Ib-IX-V complex, integrin alphaIIbbeta3, heparin, various types of collagen, and coagulation factor VIII. Among various functions, the most characteristic feature of vWF is its determinant role on platelet thrombus formation under high-shear-rate conditions. Indeed, at in vivo rheological situations where platelets are flowing with high speed in the bloodstream, the only reaction that can initiate mural thrombogenesis is the interaction of vWF with platelet glycoprotein Ibalpha. The recent x-ray analysis of the crystal structure of various functional domains and functional studies of this protein under experimental flow conditions have rapidly advanced and revised our knowledge of the structure-function relationships of vWF, a key protein for hemostasis and arterial thrombosis.     

Myocardial infarction and thromboembolism during pregnancy

Acute myocardial infarction is a very rare event during pregnancy and bears the problem of misdiagnosis. However, about 150 cases have been published worldwide with a preponderance of anterior wall infarcts. With more women delaying childbearing until an older age and increasing prevalence of smoking in young women, it can be expected that all forms of coronary artery disease--including acute myocardial infarction--will be seen more often in the future. Among the causes of coronary artery occlusion in pregnancy are (1) rupture of very small coronary artery plaques triggered by different events, e.g., hypertension; (2) plain coronary artery disease; (3) dissection of coronary arteries; (4) coronary artery spasms with/without arterial thrombosis. Prompt diagnosis and immediate therapy are necessary to lower the high mortality of mother and fetus. The gold standard in the therapy of acute myocardial infarction during pregnancy is immediate coronary angiography and percutaneous transluminal coronary angioplasty (PTCA) with or without stent implantation. Application of thrombolytics (recombinant tissue plasminogen activator [rt-PA], r-PA, streptokinase [SK], urokinase [UK]) has been reported in single patients but should be limited to cases where acute PTCA is not available and where the infarct occurs before the 14th week of pregnancy because of possible embryopathy. If the patient is in the last 10 weeks of pregnancy, anticipation of delivery should be part of the medical planning. Consultation with an obstetrician must be obtained as soon as the patient enters the hospital. Besides bleeding complications, venous thrombosis with pulmonary embolism is among the most common causes of death during pregnancy. Pregnancy-related changes in physiology - increase in the resistance to flow from the lower extremities to the heart - and congenital coagulation abnormalities are most important to be recognized. This leads to the fact that superficial and deep venous thromboses occur more often in pregnancy than in the nonpregnant state. Among the coagulation abnormalities found in pregnancy are hypercoagulability (increased levels of fibrinogen, factor VII, factor VIII, factor X), decreased fibrinolytic activity due to an increased level of plasminogen activator inhibitor, increased adhesion and aggregation of platelets, decreased level of protein C and of the APC (activated protein C) ratio. Individual risks factors justifying diagnostic screening include contraception, smoking, immobilization, infection, adiposity, placental insufficiency, and a family history of thrombosis. It is even more important to establish/rule out the diagnosis of thrombosis in pregnancy than in the nonpregnant state, because the use of anticoagulants carries certain risks during pregnancy. Doppler vein studies should be used for diagnosis. If necessary, venography may be used with shielding of the maternal abdomen. Therapy consists of subcutaneous application of heparin, compression, and early mobilization. Alternatively, especially for long-term management, treatment with low molecular weight heparins is feasible. Thrombolytic treatment is contraindicated in most cases due to the high risk of bleeding complications. However, the application of thrombolytics can be contemplated in single cases after careful consideration of the pros and cons. Most cases of pulmonary embolism should also be handled conservatively with heparin. Only in massive pulmonary embolism with severe hemodynamic compromise, thrombolytic treatment is indicated. To guide future therapy in the patients, it is necessary to establish the lifetime risk of recurrent events by determining: APC resistance, prothrombin mutation 20210 A, homocysteine, AT III, protein C and S, antiphospholipid antibodies, and anticardiolipin antibodies.     

Procoagulant versus anticoagulant factors in cirrhotic patients

Background and study aimLiver cirrhosis leads to decreased production of clotting factors that are generally all produced in the liver except factor VIII and von Willebrand factor. However, cirrhotic patients are not protected from thrombosis. The present study aimed to assess the procoagulant and anticoagulant factors in cirrhotic patients with and without bleeding and/or thrombotic events.Patients and methodsA total of 102 adult subjects were enroled: 51 cirrhotic patients and 51 healthy controls. After full history taking with special attention given to thromboembolic and haemorrhagic events, platelet count, serum albumin, bilirubin, international normalised ratio (INR), PT, partial thromboplastin time (PTT), hepatitis B surface antigen (HBsAg), hepatitis B core (HBc) antibodies, hepatitis C virus (HCV) antibodies, factor VIII, protein C, Protac-induced coagulation inhibition percentage (PICI%) assay and abdominal ultrasound were performed for patients and controls. Upper gastrointestinal endoscopy was conducted for the patients.ResultsCompared with control subjects, factor VIII and factor VIII/protein C were significantly higher, while protein C and PICI% were significantly lower among patients.ConclusionPatients with liver cirrhosis may have a tendency for bleeding or thrombosis according to the balance of coagulant and anticoagulant status. PICI%, the assay that evaluated the functionality of the protein C anticoagulant system, was significantly lower in patients compared to control subjects. Accordingly, low PICI% and high factor VIII/protein C ratio can be taken as an index of hypercoagulability in cirrhotic patients.     

Acute myocardial infarction,primary percutaneous coronary intervention and stent thrombosis in heart transplanted patient: Potential role of elevated coagulation factor VIII

Elevated factor VIII levels have been established as thrombotic risk factor. In this case report, we describe a 51 years old patient with a history of heart transplantation and acute myocardial infarction, treated by stent implantation who presented with sub-acute stent thrombosis. Elevated factor VIII levels were detected as most plausible cause of this thrombotic event. A review of the literature is also performed.     

Significance of increased factor VIII in early glomerulonephritis.

One hundred sixteen patients with early glomerulonephritis had factor VIII without impairment of renal function. They also had other coagulation and fibrinolytic components and acute phase reactants. The patients were followed for up to 4 years with respect to both coagulation pattern and renal function. Patients who made a complete recovery during follow-up had normal initial factor VIII levels, while those who developed persistent renal damage had high factor VIII levels. The other coagulation factors and the acute phase reactants were of no prognostic significance. Factor VIII has been shown to be synthesized in the vessel intima. The initial factor VIII level in early glomerulonephritis may reflect the degree of vascular affection of the glomeruli. The high factor VIII levels may be of significance for the development of fibrin deposits in glomeruli.