Thrombosis and haemorrhage in polycythaemia vera and essential thrombocythaemia

Plasma levels of angiogenic factors and circulating endothelial cells in essential thrombocythemia: correlation with cytoreductive therapy and JAK2-V617F mutational status

Recent studies have shown that angiogenesis plays an important role in the biology of hematological malignancies including essential thrombocythemia (ET). Using cytofluorimetric analysis, the levels of angiogenic factors, as well as the number of circulating endothelial cells (CECs), were determined in 65 patients with ET, including 33 previously untreated and 32 receiving cytoreductive therapy. Correlations between markers of angiogenesis and JAK2-V617F mutational status were also assessed. We found significantly higher levels of vascular endothelial growth factor (VEGF) and markedly decreased levels of placental growth factor in untreated patients with ET with respect to control subjects. VEGF levels were significantly increased in patients with white blood count >8.7 (x 10(9)/L) vs. <8.7 (x 10(9)/L). Furthermore, the levels of VEGF in patients on hydroxyurea (HU) therapy were markedly lower than in untreated patients. It was also demonstrated that the number of all CEC subpopulations (resting, activated, apoptotic, and circulating precursor endothelial cells) was increased in patients with ET in relation to controls, regardless of the JAK2-V617F status, and was not affected by cytoreductive treatment. In conclusion, our study highlights the possible role of angiogenesis in the pathophysiology of ET. It provides evidence that the number of CECs is elevated independently of JAK2-V617F status and is not down-regulated by HU or anagrelide therapy. Our data suggest that VEGF levels are particularly elevated in patients with high leukocytosis. Further investigation should be undertaken to determine the possible role of antiangiogenic therapy in ET.

Increased serum levels of neutrophil gelatinase-associated lipocalin in patients with essential thrombocythemia and polycythemia vera

Neutrophil gelatinaase-associated lipocalin (NGAL) is a glycoprotein bound with matrix metalloproteinase-9 (MMP-9) in human neutrophils, and elevated tissue NGAL expression has been documented in different infectious and inflammatory conditions. Recent evidence suggests that NGAL expression is induced in many types of human cancer. Moreover, NGAL is required for BCR-ABL-induced tumorigenesis. The aim of the present study was to measure serum levels of NGAL in patients with essential thrombocythemia (ET) and polycythemia vera (PV). We also evaluated NGAL levels in patients with ET and PV with and without thrombotic events, to explore a possible correlation of NGAL with platelet and leukocyte activation, and in patients with sepsis. Serum NGAL levels in the study population were significantly higher than in healthy adults and in subjects with sepsis. A correlation between NGAL and the number of white cells and neutrophils was found in patients with PV and ET. NGAL serum levels were not different depending on the presence or not of the JAK2 mutation, and a mutant allele dosage effect was not observed for NGAL levels. Patients with PV and ET with thrombosis did not have significantly higher levels of NGAL. We were unable to demonstrate a significant association between serum NGAL levels and CD11b or CD62 expression. In conclusion, our study reports evidence demonstrating that increased levels of NGAL appear to be a characteristic of patients with PV and ET.

Guidelines on the use of therapeutic apheresis in clinical practice--evidence-based approach from the Apheresis Applications Committee of the American Society for Apheresis

The American Society for Apheresis (ASFA) Apheresis Applications Committee is charged with a review and categorization of indications for therapeutic apheresis. Beginning with the 2007 ASFA Special Issue (fourth edition), the subcommittee has incorporated systematic review and evidence-based approach in the grading and categorization of indications. This Fifth ASFA Special Issue has further improved the process of using evidence-based medicine in the recommendations by refining the category definitions and by adding a grade of recommendation based on widely accepted GRADE system. The concept of a fact sheet was introduced in the Fourth edition and is only slightly modified in this current edition. The fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis. The article consists of 59 fact sheets devoted to each disease entity currently categorized by the ASFA as category I through III. Category IV indications are also listed.

Observation versus antiplatelet therapy as primary prophylaxis for thrombosis in low-risk essential thrombocythemia

The effectiveness of antiplatelet therapy as primary prophylaxis for thrombosis in low-risk essential thrombocythemia (ET) is not proven. In this study, the incidence rates of arterial and venous thrombosis were retrospectively analyzed in 300 low-risk patients with ET treated with antiplatelet drugs as monotherapy (n = 198) or followed with careful observation (n = 102). Follow-up was 802 and 848 person-years for antiplatelet therapy and observation, respectively. Rates of thrombotic events were 21.2 and 17.7 per 1000 person-years for antiplatelet therapy and observation, respectively (P = .6). JAK2 V617F–positive patients not receiving antiplatelet medication showed an increased risk of venous thrombosis (incidence rate ratio [IRR]: 4.0; 95% CI: 1.2-12.9; P = .02). Patients with cardiovascular risk factors had increased rates of arterial thrombosis while on observation (IRR: 2.5; 95% CI: 1.02-6.1; P = .047). An increased risk of major bleeding was observed in patients with platelet count greater than 1000 × 109/L under antiplatelet therapy (IRR: 5.4; 95% CI: 1.7-17.2; P = .004). In conclusion, antiplatelet therapy reduces the incidence of venous thrombosis in patients with JAK2-positive ET and the rate of arterial thrombosis in patients with associated cardiovascular risk factors. In the remaining low-risk patients, this therapy is not effective as primary prophylaxis of thrombosis, and observation may be an adequate option.

Progressive postinjury thrombocytosis is associated with thromboembolic complications

BACKGROUND

Our previous investigation demonstrated that despite routine chemoprophylaxis, thrombelastography, which is a comprehensive test measuring the viscoelastic properties of blood, identified a hypercoagulable state in a cohort of critically ill surgical patients that was associated with thromboemobolic events. Furthermore, because thrombelastography allows for the comprehensive assessment of coagulation status, this work suggested that platelet hyperactivity is a component of the hypercoagulable state. We hypothesized that progressive postinjury thrombocytosis contributes to a hypercoagulable state that is associated with thrombelastography.

METHODS

One thousand four hundred and forty severely injured patients surviving >48 h were entered into a database prospectively over 12 years. The variables that were evaluated in associated with thrombocytosis (platelet count >450,000) included age, Injury Severity Score, packed red blood cell transfusions in 12 h, and thromboemobolic complications (TE) (deep venous thrombosis, pulmonary embolus, mesenteric thrombosis, stroke, and arterial thrombosis). The time frame for the development of thrombocytosis was assessed at greater or less than 7 days postinjury. Logistic regression was used to identify the independent variables predictive of thrombocytosis and to adjust the association of thrombocytosis with TE for other risk factors. C-statistic was used to assess the discriminative power of thrombocytosis for prediction of TE.

RESULTS

The mean age was 37.4 ± 0.4 years. The Injury Severity Score was 29.3 ± 0.3, and mean red blood cell transfusions in 12 h was 4.4 ± 0.2 units. Injury via blunt force occurred in 76% of patients, and 72% of patients were male. Thrombocytosis was identified in 447 (31%) patients and was noted almost exclusively >7 days postinjury (98%). TE developed in 35 (8%) of the 447 patients with thrombocytosis, compared with 45 (4.5%) of the remaining 993 patients who did not develop thrombocytosis. Persistent thrombocytosis >7 days was associated with TE (P > .0001). Logistic regression analysis indicated that when adjusted for intensive care unit duration of stay, transfusions, age, and Injury Severity Score, patients with sustained thrombocytosis more than 3 days were noted to have a 1.4 × increased risk of TE (odds ratio, 1.12; 95% confidence interval, 1.04-1.2; P = .002; C-statistic = 0.82).

CONCLUSION

Persistent thrombocytosis in critically injured patients receiving routine chemoprophylaxis is associated with thrombotic complications. Subsequent investigation is warranted to differentiate enzymatic from platelet hypercoagulability to ascertain the role of antiplatelet therapy for prevention of TE.

Prognostic utility of spontaneous erythroid colony formation and JAK2 mutational analysis for thrombotic events in essential thrombocythaemia

BACKGROUND

Thrombotic events in essential thrombocythaemia (ET) are difficult to predict with current risk stratification based on age and prior history of thrombosis.

AIMS

We aimed to assess the predictive value of the JAK2 V617F mutation (JAK2) and spontaneous erythroid colony (SEC) growth for the development of thrombotic events post diagnosis in patients with ET.

METHODS

Consecutive patients with ET were retrospectively identified, and clinical and laboratory correlates were evaluated. Thrombotic events were categorized according to their occurrence at or prior to diagnosis (prior thrombosis), and any time post diagnosis of ET (subsequent thrombosis). JAK2 analysis was performed by allele-specific PCR on whole blood or bone marrow.

RESULTS

A total of 62 patients was identified, median age 63 years; 67% (41/61) JAK2-positive and 47% (25/53) SEC-positive. Median follow-up was 33 months (range, 1 to 137). JAK2-positive patients showed a trend to increased prior thrombosis (27% vs 5%, P= 0.08), and a significant increase in the development of subsequent thrombosis (5-year event rate 31% vs 6%, P= 0.04), which persisted when stratified for a history of prior thrombosis (P= 0.04). Survival was not affected by JAK2 status. The SEC assay predicted an increased rate of baseline thrombosis (16% vs 0%, P= 0.04), but was not found to be predictive of any subsequent thrombotic events.

CONCLUSIONS

Patients with ET who are JAK2-positive by whole blood allele-specific PCR appear to be at increased risk of thrombotic complications, which is independent of a prior history of thrombosis.

Evaluation of platelet function and pharmacological platelet inhibition in patients with myeloproliferative disorders using multiple electrode aggregometry

BACKGROUND

The aim of this study was to describe platelet aggregation characteristics by multiple electrode aggregometry (MEA) and to evaluate MEA for its potential to detect platelet dysfunction and response to anti-aggregatory drugs in patients with myeloproliferative disorders (MPD).

METHODS

We compared the platelet response to arachidonic acid (ASPI test), adenosine diphosphate (ADP test) and thrombin receptor activating peptide (TRAP test) in hirudin-anticoagulated blood of 55 patients with polycythaemia vera and essential thrombocythaemia and 75 controls.

RESULTS

Comparing MPD patients and controls no statistically significant difference indicative of platelet dysfunction was found in MPD patients. Analysis of covariance revealed platelet- and leukocyte count as a significant influencing factor on MEA function. Furthermore we could demonstrate that ASA and clopidogrel treatment results in a statistically significant lower ASPI (Controls: p<0.0001, MPD: p<0.0001) and ADPtest value (MPD: p=0.00125) compared to untreated patients thereby validating the method for monitoring of anti-aggregatory therapy.

CONCLUSION

In this study MEA was confirmed as a valid method for monitoring of ASA and clopidogrel treatment in patients with MPD and normal control subjects. The platelet and leukocyte count were identified as major influencing factors on MEA aggregation tests both in MPD patients and controls. No functional platelet abnormalities were detected in MPD patients.

Postpartal recurrent non-ST elevation myocardial infarction in essential thrombocythaemia: case report and review of the literature

Normal pregnancy corresponds to a procoagulant state. Acute myocardial infarction during pregnancy is rare, yet considering the low non-pregnant risk score of childbearing women it is still surprisingly frequent. We report a case of postpartum recurrent non-ST elevation myocardial infarction in a 40-year-old caucasian woman with essential thrombocythaemia in the presence of a positive JAK-2 mutation and an elevated anti-cardiolipin IgM antibody titer. In the majority of cases of myocardial infarction in pregnancy or in the peripartal period, atherosclerosis, a thrombus or coronary artery dissection is observed. The combination of essential thrombocythaemia and elevated anti-cardiolipin IgM antibody titer in the presence of several cardiovascular risk factors seems to be causative in our case. In conclusion, with the continuing trend of childbearing at older ages, rare or unlikely conditions leading to severe events such as myocardial infarction must be considered in pregnant women.

Circulating endothelial cells in essential thrombocythemia and polycythemia vera: correlation with JAK2-V617F mutational status, angiogenic factors and coagulation activation markers

Angiogenesis plays an important role in the biology of hematological malignancies, including essential thrombocythemia (ET) and polycythemia vera (PV). Some data suggests that it has a role in the pathogenesis of thrombosis, the major clinical problem in ET and PV. The number of different subpopulations of circulating endothelial cells (CECs), plasma levels of vascular endothelial growth factor (VEGF), soluble vascular endothelial growth factor receptor 1 and 2 (sVEGFR-1,2) and placenta growth factor (PlGF) were determined in 30 patients with ET and 16 patients with PV. Correlations between angiogenesis and JAK2-V617F mutational status, risk factors for thrombosis and coagulation activation markers were also assessed. The number of CEC subpopulations, were markedly higher in ET and PV patients, irrespective of JAK2-V617F status, when compared to the control group. The median values of activated CECs were markedly higher in PV patients with WBC >8.7 (x10(9)/l). Significantly higher VEGF plasma levels were found in ET patients and a similar trend was seen in PV patients in relation to healthy volunteers. The plasma levels of sVEGFR-1 were significantly higher, and PlGF levels markedly lower, in the ET and PV group than in controls. Our study also demonstrated markedly increased levels of D-dimer and TAT complexes in the patient groups. In conclusion, we found that angiogenesis, as measured by CEC numbers, is increased in ET and PV patients regardless of JAK2-V617F mutational status. Our results demonstrated that angiogenic cytokines interact with known thrombotic risk factors. We confirmed the coagulation activation in ET and PV patients but found no differences in levels of coagulation activation markers in relation to JAK2-V617F mutational status.

A Case Report of Cerebral Venous Thrombosis in Polycythemia Vera Presenting with Intracranial and Spinal Subdural Hematoma

Spinal subdural hematoma (SDH) is a rare condition and can be caused by several factors. Concomitant cranial and spinal SDH is even much less common. We present a 77-year-old male patient with lower back pain, paraparesis, and urinary retention following a sudden onset headache. Imaging revealed concomitant cranial and spinal SDH related to cerebral venous thrombosis (CVT) associated with hemorrhagic venous infarct. Laboratory examinations were consistent with polycythemia vera. There was no history of trauma and previous cranial surgery. Brain angiography did not reveal any evidence of arteriovenous fistula or vascular malformation. Since lower back pain occurred shortly after the headache and there was no other reasonable explanation for spinal hemorrhage, we suppose that the mechanism of spinal SDH is the migration of blood from the intracranial compartment. Therefore, this is the first report of concomitant spinal SDH and cerebral hemorrhage associated with CVT in a patient with myeloproliferative disease.

Relation of platelet count to bleeding and vascular complications in patients undergoing coronary angiography

Vascular and bleeding complications are associated with significant morbidity and mortality, limited data are available on the relation between these complications and the platelet count in patients undergoing coronary angiography. We, therefore, performed a retrospective cohort analysis of 3,466 consecutive adults undergoing coronary angiography at a single institution during a 2-year period. The mean + or - SD age was 60 + or - 13 years; 58% of the patients were men, 67% were white, and 27% were black. The mean platelet count was 242 + or - 86 x 10(9)/L. A total of 143 bleeding or vascular complications (4.2%), as defined using the American College of Cardiology CathPCI Registry criteria, a part of the American College of Cardiology National Cardiovascular Disease Registry, occurred. The risk of complications increased with increasing platelet counts. Compared to the quartile with the lowest platelet counts, the odds ratio (OR) for complications was 1.41 for the second quartile (95% confidence interval 0.83 to 2.37, p = 0.20), 1.74 for the third quartile (95% confidence interval 1.04 to 2.93, p = 0.04), and 2.04 for the fourth quartile (95% confidence interval 1.21 to 3.44, p = 0.008). On multivariate logistic regression analysis, age, percutaneous coronary intervention, and increasing platelet counts were independent predictors of bleeding and vascular complications. When the analysis was limited to the 2,220 patients undergoing diagnostic coronary angiography without percutaneous coronary intervention, an increasing platelet quartile was a significant predictor of vascular and/or bleeding complications (OR 1.88, p = 0.08; OR 2.48, p = 0.01; OR 2.52, p = 0.01 for the second, third, and fourth quartiles, respectively). In conclusion, the baseline platelet count was a strong and independent risk factor for bleeding and vascular complications in patients undergoing coronary angiography.

[Usefulness of JAK2 mutation assessment in recurrent deep venous thrombosis]

The search of JAK2 V617F mutation is a useful tool for the diagnosis of myeloproliferative disorders (MPD). This case report highlights the potential usefulness of this testing in recurrent deep venous thrombosis (DVT) of lower limb. We report a 73-year-old man who presented with three spontaneous episodes of lower limb DVT. The third episode occured while he was receiving fluindione. MPD was suspected because of an increased hematocrit (55 %) and hemoglobin (17g/dl) level. Red cell blood volume was increased and a JAK2 V617F mutation was detected confirming the diagnosis of polycythemia vera. The usefulness of JAK2 mutation for the diagnosis of MPD has been widely demonstrated. Also, some studies confirmed its usefulness in apparently idiopathic abdominal venous thrombosis. This report highlights the possible interest of JAK2 mutation in unexplained recurrent lower limb DVT, especially when it occurs under anticoagulant therapy.

Leukocytosis is a risk factor for recurrent arterial thrombosis in young patients with polycythemia vera and essential thrombocythemia

There is evidence that leukocytosis is associated with an increased risk of first thrombosis in patients with polycythemia vera (PV) and essential thrombocythemia (ET). Whether it is a risk factor for recurrent thrombosis too is currently unknown. In the frame of a multicenter retrospective cohort study, we recruited 253 patients with PV (n = 133) or ET (n = 120), who were selected on the basis of a first arterial (70%) or venous major thrombosis (27.6%) or both (2.4%), and who were not receiving cytoreduction at the time of thrombosis. The probability of recurrent thrombosis associated with the leukocyte count recorded at the time of the first thrombosis was estimated by a receiver operating characteristic analysis and a multivariable Cox proportional hazards regression model. Thrombosis recurred in 78 patients (30.7%); multivariable analysis showed an independent risk of arterial recurrence (hazard ratio [HR] 2.16, 95% CI 1.12-4.18) in patients with a leukocyte count that was >12.4 x 10(9)/L at the time of the first thrombotic episode. The prognostic role for leukocytosis was age-related, as it was only significant in patients that were aged <60 years (HR for arterial recurrence 3.35, 95% CI 1.22-9.19).

Essential thrombocythemia: past and present

Essential thrombocythemia (ET) is a clonal myeloproliferative disorder characterized by sustained increase in platelet number and tendency for thromboembolism. A somatic point mutation that causes a constitutive activation of the JAK2 gene is found in one in two ET patients. ET is more common in women, its incidence being 0.6-2.5/100,000 patient/year and the median age at diagnosis is 65-70 years. ET can affect all age groups, including children (0.09 cases/year), and is often diagnosed in the third-fourth decade of life. Rare cases of familial ET have been reported. Miscarriages are 3-4 times more common among women with ET than in the general population, especially in patients carrying JAK2V617F. Microvascular disturbances are typical of ET, but a major thrombosis (2/3 arterial and 1/3 venous; 1, 2-3% patient/year) is the main cause of morbidity and mortality. Age over 60 years and/or previous thrombosis are validated risk factor for thrombosis. Hemorrhages occur in 0.33% patient/year, mainly in those with a platelet count over 1,500 x 10(9)/L. Progression to myelofibrosis and leukemia is more common in patients carrying the JAK2V617F mutation, and is estimated to occur in 0.16% and 0.12% patient/year, respectively. The ET-related mortality ratio with respect to the general population is 1:1, while for polycythemia vera it is 1.6:1. Low-dose aspirin is useful for microvascular disturbances, and in the primary and secondary prevention of major thrombosis in high-risk patients, but it is not recommended in patients with a platelet count over 1,500 x 10(9)/L. Hydroxyurea is used as first-line treatment in high-risk patients. Other drugs available are alpha-interferon, anagrelide, pipobroman and busulphan.

Treatment of venous thromboembolism in patients with cancer: Guidelines of the Italian Society for Haemostasis and Thrombosis (SISET)

BACKGROUND

The treatment of venous thromboembolism (VTE) in cancer patients remains controversial.

PURPOSE

The Italian Society for Thrombosis and Haemostasis (SISET) commissioned a project to develop clinical practice guidelines for the therapy of VTE in patients with malignancies.

METHODS

Key questions about the treatment of VTE in patients with malignancies were formulated by a multidisciplinary working group consisting of experts in clinical medicine and research. After a systematic review and discussion of the literature, recommendations were formulated and graded according to the supporting evidence. For those questions for which the literature search did not yield any definitive answer (absence of evidence evidence of low quality, and contradictory evidence), a formal consensus method was used to issue clinical recommendations.

RESULTS

The results of the available literature on VTE treatment in cancer patients were reviewed and clinical recommendations were drafted.

CONCLUSION

We describe the results of a systematic literature review and an explicit approach to consensus techniques which resulted in recommendations for the key therapeutic issues in cancer patients with VTE.

Increased platelet glycoprotein Ib receptor number, enhanced platelet adhesion and severe cerebral ischaemia in a patient with polycythaemia vera

The present study describes severe multiplex cerebral ischaemic laesions in a male patient being diagnosed with polycythaemia vera (PV). In contrast to previous publications, unique platelet receptor pattern with normal platelet count was identified. Glycoprotein Ib receptor number on the surface of resting platelets was increased two-fold and almost three-fold in case of activated platelets compared to the controls. More over, in an in vitro study when whole blood was circulated both at venous and arterial shear conditions and shear rate was adjusted according to the blood viscosity, platelet aggregate/thrombus formation was characteristic on surfaces covered with purified von Willebrand factor while in case of controls the surface was covered with single platelets or platelet monolayer. Similar results with pathological findings have not been published in PV until now. Our result undersigns the necessity of antiplatelet therapy of PV patients, even at normal platelet count.

Increased risk of recurrent thrombosis in patients with essential thrombocythemia carrying the homozygous JAK2 V617F mutation

Evidence suggests that the JAK2 V617F mutation is associated with an increased risk of first thrombosis in patients with essential thrombocythemia (ET). Whether this mutation is also a risk factor for recurrent thrombosis is currently unknown. To investigate the impact of the JAK2 V617F mutation on the risk of recurrent thrombosis in patients with ET, we carried out a multicentre retrospective cohort study. We recruited 143 patients with previous arterial (64.4%) or venous major thrombosis (34.8%) or both (0.8%); 98 of them (68.5%) carried the mutation. Thrombosis recurred in 43 of the patients (30%); overall, after adjustment for sex, age, presence of vascular risk factors, and treatment after the first thrombosis, the presence of the JAK2 mutation did not predict recurrence (multivariable hazard ratio, HR, 0.88, 95% CI 0.46-1.68). Indeed, the individuals homozygous for the JAK2 V617F (allele burden >50%) mutation had an increased risk of recurrence in comparison with wild-type patients (HR 6.15, 95% CI 1.51-24.92). In conclusion, a homozygous JAK2 V617F mutation is an independent risk factor for recurrent thrombosis in patients with ET.

Elevated procoagulant microparticles expressing endothelial and platelet markers in essential thrombocythemia

BACKGROUND

Most cell types, including blood--and vascular cells, produce microparticles upon activation. Since cellular microparticles are known to be elevated in thromboembolic diseases, we hypothesized a role for microparticles in the pathogenesis of thrombosis in essential thrombocythemia.

DESIGN AND METHODS

In plasma samples from 21 patients with essential thrombocythemia and ten healthy subjects, the levels and the cellular origin of microparticles were determined by flowcytometric analysis, while the microparticle-associated procoagulant activity was measured using a thrombin generation assay.

RESULTS

Patients with essential thrombocythemia had significantly higher numbers of circulating annexin V-positive microparticles than controls (median 4500 vs. 2500x10(6) events/L; p=0.039), including significantly higher numbers of microparticles positive for the platelet marker CD61 (p=0.043), the endothelial markers CD62E (p=0.009) and CD144 (p=0.021), and for tissue factor (p=0.036). CD62E was co-expressed with the platelet marker CD41 on microparticles, suggesting a bilineage origin of such microparticles, which were observed only in patients with risk factors for thrombosis. Patients with essential thrombocythemia had higher plasma levels of mature von Willebrand factor (p=0.045) but similar propeptide levels compared to controls. In thrombin generation analyses, microparticle-rich plasma from patients with essential thrombocythemia had a shorter lag time (p=0.001) and higher peak height (p=0.038) than plasma from controls. Peak height correlated significantly with the total number of microparticles (R=0.634, p<0.001).

CONCLUSIONS

Patients with essential thrombocythemia had higher number of circulating microparticles with platelet and endothelial markers, suggesting ongoing platelet and endothelial activation. This was confirmed by an increased level of mature von Willebrand factor, an abnormal mature von Willebrand factor/propeptide ratio, and a hypercoagulable state reflected in thrombin generation. These findings suggest a role for microparticles in thrombosis in essential thrombocythemia.

Role of platelet counts in the management of essential thrombocythemia: experience with anagrelide

An elevated platelet count is the hallmark of essential thrombocythemia (ET). Therapeutic control of platelet counts in ET has proven effective for minimizing the risk of bleeding complications. By contrast, the relationship between platelet count and thrombotic complications is less well defined. The beneficial effects of lowering the platelet count are greatest when levels are reduced close to or within the normal range, thus supporting the trend within the medical community to reduce platelet treatment targets to below 400-450 × 10(9)/l. Platelet counts have further utility in ET as a marker to indicate intolerance/resistance to hydroxyurea according to recently published guidelines. In the current era, where novel risk factors for ET complications are being discussed, this article takes a back-to-basics approach, considering what platelet counts reveal in practice as a risk factor for complications and a marker of treatment efficacy, with particular focus on data for the platelet-selective agent anagrelide.

Article Commentary: Symptomatic Splenomegaly in Polycythemia Vera: A Review of the Indications for Splenectomy and Perioperative Considerations

Polycythemia vera is a condition that surgeons do not commonly encounter. Advances in medical management have largely led to avoidance of surgical intervention in most patients. Indications and timing of splenectomy have been the subject of debate since the disease was first described in the late 19th century. Though anemia and thrombocytopenia associated with polycythemia vera only transiently respond to splenectomy, painful splenomegaly with infarction or compression of surrounding viscera are presently accepted indications for surgery. Special consideration must be given to polycythemia vera patients both preoperatively and postoperatively due to altered coagulation and anatomy. We present a review of the pathophysiology, medical treatment, indications for surgical intervention, and perioperative considerations for polycythemia vera.

[Essential thrombocythaemia as a causative agent of portal vein thrombosis--a case report]

INTRODUCTION

Thrombosis of splanchnic blood vessels is one of the most difficult complications and most frequent causes of death in patients with myeloproliferative disorders.

CASE OUTLINE

We report a 48-year-old man with recurring haemorrhage from the upper digestive tract. Doppler ultrasonography of the portal system revealed a thrombosed portal vein, with marginal flow of 10 cm/s. Peroral fiber panendoscopy of the oesophagus showed III-IV degree varices together with varices in the stomach fundus. Blood count revealed thrombocytosis (Pt. 900 x 109/l), and haematological analysis led to the diagnosis of essential thrombocythaemia. However, two years after the established diagnosis, the patient was hospitalized again for bleeding from esophageal varicosity. During haemorrhage, anticoagulant therapy was discontinued. Eight days after anticoagulant discontinuation, mesenterial thrombosis and small intestinal gangrene developed. Surgical intervention was carried out, including resection of 2.5 m of the small intestine. In spite of intensive postoperative therapy, the lethal outcome ensued.

CONCLUSION

The bleeding from oesophageal and/or gastric varicosity is often the presenting manifestation of up to that time undetected myeloproliferative disease. The following question still remains open: should anticoagulant therapy be continued in the phase of acute bleeding of these patients?

Influence of the JAK2 V617F mutation and inherited thrombophilia on the thrombotic risk among patients with essential thrombocythemia

It is uncertain whether the JAK2 V617F mutation increases the thrombotic risk in patients with essential thrombocythemia, and it is unknown whether inherited thrombophilia is an additive risk factor in mutated subjects. We studied 132 patients with essential thrombocythemia, 38 of them (29%) with a history of thrombosis. The JAK2 mutation was present in 83 (63%), and inherited thrombophilia in 7. The mutated patients <60 years had a relative risk (RR) for thrombosis at any time of 3.83 (95%CI 1.27-11.49) in comparison with wild-type patients; in those with both the mutation and thrombophilia the RR was 2.23 (95%CI 1.57-3.18) and 7.66 (95%CI 2.66-22.03) in comparison with mutated or wild-type patients without thrombophilia, respectively. During the follow-up, only the homozygotes for JAK2 V617F were more prone to thrombosis (RR 17.25, 95%CI 2.33-127.4). Among the patients >60 years, no increase in RR was associated with the JAK2 mutation. In conclusion, in the younger patients with ET the thrombotic risk is higher in the JAK2 V617F-mutated and is further increased by the presence of inherited thrombophilia.

Association of V617F Jak2 mutation with the risk of thrombosis among patients with essential thrombocythaemia or idiopathic myelofibrosis: a systematic review

INTRODUCTION

Many studies evaluated the association of V617F Jak-2 with the risk of thrombosis in patients with essential thrombocythaemia, but the results of these studies were inconsistent. Few studies evaluated the association of V617F Jak-2 mutation with the risk of thrombosis in patients with idiopathic myelofibrosis. Therefore, we performed a systematic review of the studies that assessed the risk of thrombosis associated with V617F Jak-2 in patients with ET or IM.

MATERIALS AND METHODS

We searched MEDLINE and EMBASE databases and reference lists of retrieved articles. Odds ratios (ORs) and 95% confidence intervals (CI) were calculated for each trial and pooled.

RESULTS

We included 21 studies involving patients with essential thrombocythaemia and 6 studies patients with idiopathic myelofibrosis. In essential thrombocythaemia patients, V617F Jak-2 was associated with a significant increased risk of thrombosis (OR 1.92, 95% CI 1.45-2.53), both of venous (OR 2.49, 95% CI 1.71-3.61) and arterial (OR 1.77, 95% CI 1.29-2.43) vessels. In idiopathic myelofibrosis patients, the risk of thrombosis associated with V617F Jak-2 tended to be increased (OR 1.76, 95% CI 0.91-3.41).

CONCLUSIONS

Our systematic review suggests that V617F Jak-2 increases the risk of thrombosis in essential thrombocythaemia patients by about two fold while its role in idiopathic myelofibrosis patients is uncertain.

Nadroparine-induced skin necrosis on a patient with essential thrombocythaemia: a case report

Skin necrosis is a rare but serious complication of subcutaneously administered low-molecular-weight heparin. We report a case of a 53-year-old female patient with skin necrosis induced by subcutaneous administration of nadroparine. The patient suffered from essential thrombocythaemia on a background of chronic myeloproliferative disease. She was admitted to our clinic with a subacute ileus due to endometriosis of the rectosigmoid junction. She underwent a high anterior resection and she received pre- and postoperative antithrombotic prophylaxis with subcutaneous nadroparine on a daily basis. On the 6^th and 7^th postoperative days, two skin necroses occurred at two injection sites.

Nadroparine-induced skin necrosis on a patient with essential thrombocythaemia: a case report

Skin necrosis is a rare but serious complication of subcutaneously administered low-molecular-weight heparin. We report a case of a 53-year-old female patient with skin necrosis induced by subcutaneous administration of nadroparine. The patient suffered from essential thrombocythaemia on a background of chronic myeloproliferative disease. She was admitted to our clinic with a subacute ileus due to endometriosis of the rectosigmoid junction. She underwent a high anterior resection and she received pre- and postoperative antithrombotic prophylaxis with subcutaneous nadroparine on a daily basis. On the 6th and 7th postoperative days, two skin necroses occurred at two injection sites.

New and old prognostic factors in polycythemia vera

Polycythemia vera is a chronic myeloproliferative disorder affecting people in the sixth decade of life. The disease is considered long-lasting; median survival exceeds 18 years. As thrombosis is the main complication during follow-up, scoring systems have focused on the risk of thrombosis. Age over 60 years and prior thrombosis are considered the standard risk factors for thrombosis and represent the state of the art for risk stratification in decision making regarding treatment. However, new disease-based risk factors-leukocytosis and the JAK2V617F mutation burden-seem to be emerging as indicators of prognosis in polycythemia vera. Leukocytosis, as a marker of disease proliferation, seems to have an impact on thrombosis, post-polycythemia vera myelofibrosis, leukemia, and survival. The role of the JAK2V617F mutation as a prognostic factor requires further validation, but it may have a dominant role in disease progression and in the activation of platelets and leukocytes.

Thrombin generation and activated protein C resistance in patients with essential thrombocythemia and polycythemia vera

We used the thrombin generation assay to evaluate the hypercoagulable state according to JAK2V617F mutational status in essential thrombocythemia (ET) and polycythemia vera (PV) patients. Thrombin generation was determined in the presence and absence of activated protein C (APC), and APC resistance was expressed as normalized APC sensitivity ratio (nAPCsr). Tissue factor pathway inhibitor (TFPI), total and free protein S (PS), prothrombin (FII), factor V (FV), and neutrophil elastase were measured in plasma; CD11b was measured on neutrophils. Compared with normal controls, patients had a lower endogenous thrombin potential in the absence of APC but had a higher endogenous thrombin potential in the presence of APC, showing the occurrence of APC resistance. The nAPCsr increased in JAK2V617F carriers compared with noncarriers and was highest in JAK2V617F homozygous patients. FII, FV, free PS, and TFPI levels were reduced in patients, mainly in JAK2V617F carriers. Multiple regression analysis indicated the low free PS level as major determinant of the increased nAPCsr. Elastase was increased in patients and inversely correlated with free PS. In conclusion, these data indicate the occurrence of acquired APC resistance in ET and PV patients, probably because of a reduction in free PS levels. The APC-resistant phenotype is influenced by the JAK2V617F mutational load.

JAK2V617F mutation in patients with portal vein thrombosis

In a retrospective cohort, we investigated the presence of the JAK2V617F mutation in chronic non-cirrhotic portal vein thrombosis (PVT) patients, irrespective of the presence or absence of myeloproliferative diseases (MPDs). We identified 25 patients in whom thrombophilia workup was completed. The diagnoses of MPDs were made according to the World Health Organization (WHO) criteria. JAK2V617F mutation analysis was performed by allele-specific polymerase chain reaction (PCR). There were 9 male and 16 female patients. Prior to JAK2V617F analysis, there were one or more thrombophilic risk factors in 19 patients (76%). The JAK2V617F mutation analysis revealed the presence of this mutation (all in the heterozygote state) in six patients (24%; two male, four female). Five of the six cases with prior clinical diagnosis of MPDs were found to have wild-type JAK2. We found that the addition of JAK2V617F analysis into the thrombophilia workup in patients with chronic PVT contributes to a 4% increase in the diagnosis of thrombophilic conditions.