Incidence and clinical risk factors for bleeding and thrombotic complications in myeloproliferative disorders. A retrospective analysis of 260 patients

Use of nailfold video capillaroscopy in polycythemia vera

Objectives

In this study, we aimed to investigate capillary vessel diameters and structural changes of capillaries by using nailfold video capillaroscopy (NVC) in patients with polycythemia vera (PV).

Patients and methods

This cross-sectional study included a total of 24 patients (19 males, 5 females; mean age: 59.8±12.9 years; range, 50.2 to 68 years) who were diagnosed with PV and 15 healthy controls (11 males, 4 females; mean age: 40.7±5.1 years; range, 36 to 44 years) between June 2016 and February 2017. Nailfold video capillaroscopy was performed by an experienced rheumatologist who was blinded to clinical data. The apical, arterial, and venous limb diameters of capillaries were measured and microvascular changes of capillaries were scored.

Results

When capillaries were evaluated in terms of morphological structures, giant capillary was detected in 67% of the patients with PV and 0% in the control group (p<0.05). The arterial, venous, and apical diameters of the capillaries were significantly higher in the patients with PV compared to the control group (p<0.001).

Conclusion

The presence of giant capillaries and the marked increase of arterial, venous, and apical diameters of capillaries seem to be related to PV. As it additionally plays an important role in diagnosis, prognosis, and treatment monitoring of certain diseases, capillaroscopy can be considered to be a promising microcirculation biomarker.

Reducing Wound Hemorrhage: Use of Bilayer Collagen Matrix in Chronic Myelogenous Leukemia

Summary: Donor site preparation is a critical step before the application of an autologous split-thickness skin graft (STSG). Comorbidities can lead to complications and graft loss, including that due to hematoma. In this case, a bilayer collagen matrix was used as a temporary wound dressing in a 25-year-old woman with active chronic myelogenous leukemia. She presented with a bleeding diathesis and spontaneous intramuscular and intracompartmental hematomas of the right leg. She experienced ongoing high-volume blood loss from her fasciotomy wounds, requiring wound care to be performed in the operating room under general anesthesia, and requiring multiple blood and platelet transfusions. Instead of immediate STSG, a bilayer collagen matrix was placed to reduce the bleeding and further prepare the wound bed over a 9-week period while she underwent medical optimization. Once stabilized from a hematologic standpoint, STSG was performed with total graft take. Both uncontrolled chronic myelogenous leukemia and its therapy, tyrosine kinase inhibitors, have a risk of hemorrhagic and thrombotic complications. Bilayer collagen matrix serves as an adjunct in the limb salvage algorithm that can reduce transfusion needs whereas a temporary bleeding diathesis is medically corrected before the application of an autologous skin graft.

Platelet Function Tests and Inflammatory Markers for the Differentiation of Primary Thrombocytosis and Secondary Thrombocytosis

Background:

The prognosis and management of primary thrombocytosis (PT) and secondary thrombocytosis (ST) are different. This study aims to evaluate the role of platelet function tests by light transmission platelet aggregometry (LTA), plasma von Willebrand factor antigen (vWF:Ag), ristocetin cofactor activity (vWF:RCo) and inflammatory markers [erythrocyte sedimentation rate (ESR), C-reactive protein (CRP)] for the differentiation between PT and ST.

Methods:

This prospective study was carried out in patients with platelet counts greater than 450 x 109/L. Primary outcomes were the sensitivity and specificity of platelet function tests by LTA for the differentiation of PT and ST. Secondary outcomes were sensitivity and specificity of ESR, CRP, vWF:Ag, and vWF:RCo for the differentiation of PT and ST.

Results:

Fifty-two patients were enrolled onto the study of which 26 (50%) had PT. The sensitivity and specificity of epinephrine, collagen, and arachidonic acid (AA) induced abnormal LTA for the differentiation of PT from ST were sensitivity of 50%, 38.5%, 26.9% and specificity of 88.5%, 100%, 100% respectively. The sensitivity and specificity of abnormal ESR, CRP, and either abnormal ESR or CRP in the differentiation of ST from PT were sensitivity of 88.5%, 80.8%, 100% and specificity of 65.4%, 61.5%, 46.2% respectively. The sensitivity and specificity of low vWF:Ag and vWF:RCo in the differentiation of PT from ST were sensitivity of 7.69%, 42.3% and specificity of 100%, 88.5% respectively.

Conclusions:

Abnormal platelet function determined by LTA with collagen, AA, epinephrine had high specificity ratings enabling the differentiation between PT and ST. vWF:RCo, ESR and CRP levels could be helpful in differentiating between PT and ST.

TKI-Related Platelet Dysfunction Does Not Correlate With Bleeding in Patients With Chronic Phase-Chronic Myeloid Leukemia With Complete Hematological Response

Bleeding has been reported in patients with chronic myeloid leukemia (CML) using tyrosine kinase inhibitors (TKIs). In this study, we aimed to evaluate platelet functions and associated bleeding symptoms in patients with CML using TKIs. A standardized questionnaire that was developed for inherited bleeding disorders (ISTH/SSC Bleeding Assessment Tool) was used to score bleeding symptoms in 68 chronic phase patients with CML receiving imatinib (n = 47), dasatinib (n = 15), or nilotinib (n = 6). Light transmission aggregometry was used for platelet function testing. None of the patients had major bleeding (score > 3). Minor bleeding was observed in 25.6% and 20% of the patients in imatinib and dasatinib treatment groups. Impaired/decreased platelet aggregation was observed in 29.8% of imatinib treatment group, 50% of nilotinib group, and 40% of dasatinib group. A secondary aggregation abnormality compatible with the release defect was observed in 26% of patients with CML; 25.5%, 33.3%, and 16.7% of patients receiving imatinib, dasatinib, and nilotinib, respectively. No correlation was found between bleeding symptoms and the impaired platelet function. We can conclude that TKIs may impair in vitro platelet aggregation but this impairment is not associated with bleeding diathesis.

Major hemorrhage in chronic lymphocytic leukemia patients in the US Veterans Health Administration system in the pre-ibrutinib era: Incidence and risk factors

Chronic lymphocytic leukemia (CLL) patients are at increased risk for major hemorrhage (MH). We examined incidence of and risk factors for MH in CLL patients before introduction of newer CLL therapies such as ibrutinib, which includes bleeding risk. This study included 24 198 CLL patients treated in the VA system before FDA approval of ibrutinib as CLL therapy. Data came from VA databases from 1999 to 2013. MH incidence was 1.9/100 person-years (95% CI: 1.8-1.9), with cumulative incidences of 2.3%, 5.2%, and 7.3% by year 1, 3, and 5, respectively. Median time from CLL diagnosis to MH was 2.8 years (range: 0-15.7 years). In multivariate analyses, concurrent anticoagulant and antiplatelet use (HR: 4.2; 95% CI: 3.2-5.6), anticoagulant use only (HR: 2.6; 95% CI: 2.3-3.1), and antiplatelet use only (HR: 1.5; 95% CI: 1.3-1.7) increased MH risk vs not receiving those medications; being nonwhite, male, having MH history, renal impairment, anemia, thrombocytopenia, and alcohol abuse were associated with increased MH risk. These pre-ibrutinib data are important for providing context for interpreting MH risk in ibrutinib-treated patients. As ibrutinib clinical use is increasing, updated analyses of MH risk among ibrutinib-treated VA patients with CLL may provide additional useful insight.

Re-evaluation of hematocrit as a determinant of thrombotic risk in erythrocytosis

Here we critically evaluate the role of elevated hematocrit as the principal determinant of thrombotic risk in polycythemia and erythrocytosis, defined by an expansion of red cell mass. Since red cell volume determination is no longer readily available, in clinical practice, polycythemia and erythrocytosis are defined by elevated hemoglobin and hematocrit. Thrombosis is common in Chuvash erythrocytosis and polycythemia vera. Although the increased thrombotic risk is assumed to be due to the elevated hematocrit and an associated increase in blood viscosity, thrombosis does not accompany most types of erythrocytosis. We review studies indicating that the occurrence of thrombosis in Chuvash erythrocytosis is independent of hematocrit, that the thrombotic risk is paradoxically increased by phlebotomy in Chuvash erythrocytosis, and that, when compared to chemotherapy, phlebotomy is associated with increased thrombotic risk in polycythemia vera. Inherited and environmental causes that lead to polycythemia and erythrocytosis are accompanied by diverse cellular changes that could directly affect thrombotic risk, irrespective of the elevated hematocrit. The pressing issue in these disorders is to define factors other than elevated hematocrit that determine thrombotic risk. Defining these predisposing factors in polycythemia and erythrocytosis should then lead to rational therapies and facilitate development of targeted interventions.

The BCR-ABL1 Inhibitors Imatinib and Ponatinib Decrease Plasma Cholesterol and Atherosclerosis, and Nilotinib and Ponatinib Activate Coagulation in a Translational Mouse Model

Treatment with the second and third generation BCR-ABL1 tyrosine kinase inhibitors (TKIs) increases cardiovascular risk in chronic myeloid leukemia (CML) patients. We investigated the vascular adverse effects of three generations of TKIs in a translational model for atherosclerosis, the APOE*3Leiden.CETP mouse. Mice were treated for sixteen weeks with imatinib (150 mg/kg BID), nilotinib (10 and 30 mg/kg QD) or ponatinib (3 and 10 mg/kg QD), giving similar drug exposures as in CML-patients. Cardiovascular risk factors were analyzed longitudinally, and histopathological analysis of atherosclerosis and transcriptome analysis of the liver was performed. Imatinib and ponatinib decreased plasma cholesterol (imatinib, −69%, p < 0.001; ponatinib 3 mg/kg, −37%, p < 0.001; ponatinib 10 mg/kg−44%, p < 0.001) and atherosclerotic lesion area (imatinib, −78%, p < 0.001; ponatinib 3 mg/kg, −52%, p = 0.002; ponatinib 10 mg/kg, −48%, p = 0.006), which were not affected by nilotinib. In addition, imatinib increased plaque stability. Gene expression and pathway analysis demonstrated that ponatinib enhanced the mRNA expression of coagulation factors of both the contact activation (intrinsic) and tissue factor (extrinsic) pathways. In line with this, ponatinib enhanced plasma levels of FVII, whereas nilotinib increased plasma FVIIa activity. While imatinib showed a beneficial cardiovascular risk profile, nilotinib and ponatinib increased the cardiovascular risk through induction of a pro-thrombotic state.

The underappreciated risk of thrombosis and bleeding in patients with myelofibrosis: a review

Bleeding and thrombosis are long recognized complications of myelofibrosis (MF) and contribute significantly to its morbidity and mortality. However, so far, few studies have evaluated the frequency of these events, their characteristics, and their prognostic impact. Based on these studies, thrombotic events in MF are about as common as in essential thrombocytemia (ET) but less common than in polycythemia vera (PV), while bleeding events are relatively more common in MF than in ET or PV. The emergence of the concept of prefibrotic primary MF (PMF), which is associated with a higher frequency of thrombohemorrhagic complications than ET, and the growing evidence that prefibrotic PMF may also have a different thrombotic and bleeding risk profiles than fibrotic (overt) PMF have emphasized the need for a reappraisal of the risk of thrombosis and hemorrhage in patients with MF. In this review, we discuss the frequency of thrombosis and bleeding in patients with MF, including prefibrotic PMF and their established and potential risk factors.

Acute compartment syndrome as the initial manifestation of chronic-phase chronic myeloid leukemia: a case report and review of the literature

Background

Acute compartment syndrome is an orthopedic emergency requiring urgent fasciotomy to prevent irreversible damage. In hematological malignancies, acute compartment syndrome caused by severe soft tissue bleeding is extremely rare. We present a patient with chronic-phase chronic myeloid leukemia who had acute compartment syndrome caused by severe soft tissue bleeding in her right forearm.

Case presentation

A 72-year-old Japanese woman was referred to our hospital with swelling and pain of her right forearm without a previous history of trauma. She was diagnosed with chronic-phase chronic myeloid leukemia. Extreme thrombocytosis was present, although no evidence of acquired von Willebrand disorder was found. Compartment syndrome caused by soft tissue bleeding was confirmed. An emergency fasciotomy for decompression was conducted. However, sustained postoperative bleeding occurred and required massive red cell concentrate transfusion. As her platelet count decreased by cytoreductive therapy, complete hemostasis was achieved.

Conclusions

Patients with an extremely high platelet count might be at high risk for severe bleeding complications even without acquired von Willebrand disease. For the control of severe bleeding complications in patients with myeloproliferative disorder, the importance of thrombocyte reduction should be recognized.

Obstetric Complications and Management in Chronic Myeloid Leukemia

Chronic myeloid leukaemia (CML) is amongst the most common haematological malignancies encountered in adults. The younger age of onset and increased incidence of CML in Indians leads to higher chances of encountering it in pregnancy. Pregnancy in CML is a complex situation as first line therapy with tyrosine kinase inhibitors (TKI), is fraught with multiple fetal safety issues. The fetal aspects have been elucidated in literature, but there is scarcity of information on the obstetric outcome per se in presence of CML, excluding the influence of TKI. Obstetric outcomes of 5 pregnancies in four patients with CML are being reported. Literature on interplay of CML and bleeding or thrombotic manifestations is reviewed. The major complications encountered were antepartum (APH) and postpartum haemorrhage (PPH), preterm labour, intrauterine growth retardation and intrauterine fetal death. Patients in the reproductive age group with diagnosis of CML should be carefully counseled regarding the effect of disease and TKI on the maternal-fetal health. Bleeding complications, particularly APH and PPH may be encountered in CML patients. Close coordination of the obstetrician, haematologist, and neonatologist is required in managing these cases successfully. The need for absolute contraception till the remission of disease needs to be emphasized for further pregnancies.

Atypical Chronic Myeloid Leukemia in Two Pediatric Patients

Atypical chronic myeloid leukemia, BCR-ABL1-negative, (aCML) is a rare myeloid neoplasm. Recent adult data suggest the leukemic cells in a subset of patients are dependent on JAK/STAT signaling and harbor CSF3R-activating mutations. We hypothesized that, similar to adult patients, the presence of CSF3R-activating mutations would be clinically relevant in pediatric myeloid neoplasms as patients would be sensitive to the JAK inhibitor, ruxolitinib. We report two cases of morphologically similar pediatric aCML, BCR-ABL1-negative based on WHO 2008 criteria. One patient had CSF3R-activating mutation (T618I) and demonstrated a robust response to ruxolitinib, which was used to bridge to a successful stem cell transplant. The other patient did not have a CSF3R-activating mutation and succumbed to refractory disease <6 months from diagnosis. This report documents CSF3R-T618I in pediatric aCML and demonstrates the efficacy of ruxolitinib in a pediatric malignancy. As the third documented case successfully treating aCML with ruxolitinib, this case highlights the importance of prompt CSF3R sequencing analysis for myeloproliferative and myelodysplastic/myeloproliferative neoplasms.

Renal Bleeding Due to Extramedullary Hematopoiesis in a Patient With Chronic Myelogenous Leukemia

Chronic myelogenous leukemia (CML) is a myeloproliferative disorder that normally presents in middle-aged adults. Renal infiltration and extramedullary hematopoiesis in renal tissue has been rarely reported. This case report presents a patient with CML and renal insufficiency who developed gross hematuria. Efforts at controlling the hematuria led to a cascade of events propelled by the underlying disorder that ultimately led to a radical nephrectomy, multiorgan failure, and prolonged hospitalization. We suggest that management of gross hematuria in clinically stable patients with CML, suspected of having extramedullary hematopoiesis, should prioritize treatment of the myeloproliferative disorder over efforts to control bleeding.

Massive splenic infarction and portal vein thrombosis in children with chronic myeloid leukemia

Massive splenic infarction and portal vein thrombosis (PVT) due to chronic myeloid leukemia (CML) is extremely rare. We describe 2 children who were presented with massive splenic infarction and PVT in the course of CML. Massive splenic infarction and PVT treated with splenectomy in one and with medical treatment in another in whom PVT resolved by cytoreductive treatment, led to downsizing of spleen or splenectomy. Splenic infarct and PVT should be considered in CML patients with long-lasting severe abdominal pain despite appropriate medical attempts. Splenectomy should be spared for persistent symptoms and complications.

Chronic myeloproliferative diseases

The chronic myeloproliferative disorders are a group of diseases in which there is an increased proliferation of one or more subtypes of myeloid cells; they include essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF). In ET and PV the main neurologic manifestations are headaches, dizziness and macro- and microvascular, both venous and arterial, thrombosis and intracranial hemorrhages. Paresthesias and chorea also occur in PV. In PMF neurologic complications are very rare and consist predominantly of spinal cord compression by extramedullary hematopoiesis tissue.

The thrombotic events in polycythemia vera patients may be related to increased oxidative stress

OBJECTIVE

This study was designed to compare the oxidative stress parameters of patients with polycythemia vera (PV) to those of healthy volunteers and to investigate the probable relationship between vascular events and parameters of oxidative status such as total oxidative status (TOS), total antioxidant status, oxidative stress index (OSI) and malondialdehyde (MDA) in PV patients.

MATERIAL AND METHODS

Thirty-five PV patients (20 males and 15 females) and 20 healthy volunteers (11 males and 9 females) were enrolled. The oxidative status parameters of the patients were measured by spectrophotometric analyses at the time of diagnosis and at 6 months after treatment which consisted of phlebotomy and 100 mg/day acetyl salicylic acid with or without hydroxyurea for the high- and low-risk disease group, respectively. These parameters were compared both to healthy controls and to each other, in order to obtain the values before and after treatment. In addition, during diagnosis, the oxidative status parameters of patients with PV and a history of a vascular event were compared with those of patients with no history of a vascular event.

RESULTS

The TOS, OSI and MDA values were significantly higher in the patients than in the control group at the time of diagnosis. At 6 months after phlebotomy and 100 mg/day acetyl salicylic acid therapy, the TOS, OSI and MDA values were significantly lower in the patients when compared to the pretreatment values. The TOS and OSI levels were notably higher in the patients with a vascular-event history than in those without this history.

CONCLUSION

Oxidative stress parameters were increased in PV patients.

Portal hypertension and myeloproliferative neoplasms: a relationship revealed

Background/Objectives. Patients with myeloproliferative neoplasms have a well-established increased risk of thrombosis. Many trials report identification of an underlying myeloproliferative neoplasm by investigation of the patients developing portal hypertensive esophagus and/or fundus variceal hemorrhage in the absence of any known etiology. This trial was designed to investigate the association between myeloproliferative neoplasms and portal hypertension and to detect the frequency of portal hypertension development in this subset of patients. Methodology. Twenty-nine patients previously diagnosed with polycythemia vera, essential thrombocytopenia, and primary myelofibrosis, who were under followup at the hematology outpatient clinic of our hospital, were included in the trial. Results. In our trial, we detected portal hypertension in 13.8% of the patients (n = 4), as a finding that was similar to those obtained in other studies performed to date. Conclusions. Considering the fact that diagnosis of myeloproliferative neoplasms usually takes a long time, treatment should be started (while, on the other hand, assessing the investigational and therapeutical choices for the complications) right after the bone marrow biopsy or cytogenetic studies required for establishing the final diagnosis have been performed.

Splanchnic vein thrombosis in myeloproliferative neoplasms

Splanchnic vein thrombosis (SVT) is one of the most important complications of myeloproliferative neoplasms (MPN). Although MPN are common causes of SVT, the pathophysiological mechanisms underlying this predisposition, their epidemiology and natural history are not fully understood. Studies have concentrated on the generalized prothrombotic environment generated by MPN and their relationship with abnormal blood counts, thereby furthering our knowledge of arterial and venous thrombosis in this population. In contrast, there are few studies that have specifically addressed SVT in the context of MPN. Recent research has demonstrated in patients with MPN the existence of factors increasing the risk of SVT such as the presence of the JAK2 V617F mutation and its 46/1 haplotype. Features unique to the circulating blood cells, splanchnic vasculature and surrounding micro-environment in patients with MPN have been described. There are also abnormalities in local haemodynamics, haemostatic molecules, the spleen, and splanchnic endothelial and endothelial progenitor cells. This review considers these important advances and discusses the contribution of individual anomalies that lead to the development of SVT in both the pre-neoplastic and overt stage of MPN. Clinical issues relating to epidemiology, recurrence and survival in these patients have also been reviewed and their results discussed.

Cancers predispose neutrophils to release extracellular DNA traps that contribute to cancer-associated thrombosis

Cancer-associated thrombosis often lacks a clear etiology. However, it is linked to a poor prognosis and represents the second-leading cause of death in cancer patients. Recent studies have shown that chromatin released into blood, through the generation of neutrophil extracellular traps (NETs), is procoagulant and prothrombotic. Using a murine model of chronic myelogenous leukemia, we show that malignant and nonmalignant neutrophils are more prone to NET formation. This increased sensitivity toward NET generation is also observed in mammary and lung carcinoma models, suggesting that cancers, through a systemic effect on the host, can induce an increase in peripheral blood neutrophils, which are predisposed to NET formation. In addition, in the late stages of the breast carcinoma model, NETosis occurs concomitant with the appearance of venous thrombi in the lung. Moreover, simulation of a minor systemic infection in tumor-bearing, but not control, mice results in the release of large quantities of chromatin and a prothrombotic state. The increase in neutrophil count and their priming is mediated by granulocyte colony-stimulating factor (G-CSF), which accumulates in the blood of tumor-bearing mice. The prothrombotic state in cancer can be reproduced by treating mice with G-CSF combined with low-dose LPS and leads to thrombocytopenia and microthrombosis. Taken together, our results identify extracellular chromatin released through NET formation as a cause for cancer-associated thrombosis and unveil a target in the effort to decrease the incidence of thrombosis in cancer patients.

A novel murine model of myeloproliferative disorders generated by overexpression of the transcription factor NF-E2

Mice expressing a transgene encoding the transcription factor NF-E2 in hematopoietic cells exhibit features of myeloproliferative neoplasms, including thrombocytosis, Epo-independent colony formation, stem and progenitor cell overabundance, leukocytosis, and progression to acute myeloid leukemia.

The molecular pathophysiology of myeloproliferative neoplasms (MPNs) remains poorly understood. Based on the observation that the transcription factor NF-E2 is often overexpressed in MPN patients, independent of the presence of other molecular aberrations, we generated mice expressing an NF-E2 transgene in hematopoietic cells. These mice exhibit many features of MPNs, including thrombocytosis, leukocytosis, Epo-independent colony formation, characteristic bone marrow histology, expansion of stem and progenitor compartments, and spontaneous transformation to acute myeloid leukemia. The MPN phenotype is transplantable to secondary recipient mice. NF-E2 can alter histone modifications, and NF-E2 transgenic mice show hypoacetylation of histone H3. Treatment of mice with the histone deacetylase inhibitor (HDAC-I) vorinostat restored physiological levels of histone H3 acetylation, decreased NF-E2 expression, and normalized platelet numbers. Similarly, MPN patients treated with an HDAC-I exhibited a decrease in NF-E2 expression. These data establish a role for NF-E2 in the pathophysiology of MPNs and provide a molecular rationale for investigating epigenetic alterations as novel targets for rationally designed MPN therapies.

Lytic resistance of fibrin containing red blood cells

OBJECTIVE

Arterial thrombi contain variable amounts of red blood cells (RBCs), which interact with fibrinogen through an eptifibatide-sensitive receptor and modify the structure of fibrin. In this study, we evaluated the modulator role of RBCs in the lytic susceptibility of fibrin.

METHODS AND RESULTS

If fibrin is formed at increasing RBC counts, scanning electron microscopy evidenced a decrease in fiber diameter from 150 to 96 nm at 40% (v/v) RBCs, an effect susceptible to eptifibatide inhibition (restoring 140 nm diameter). RBCs prolonged the lysis time in a homogeneous-phase fibrinolytic assay with tissue plasminogen activator (tPA) by up to 22.7±1.6%, but not in the presence of eptifibatide. Confocal laser microscopy using green fluorescent protein-labeled tPA and orange fluorescent fibrin showed that 20% to 40% (v/v) RBCs significantly slowed down the dissolution of the clots. The fluorescent tPA variant did not accumulate on the surface of fibrin containing RBCs at any cell count above 10%. The presence of RBCs in the clot suppressed the tPA-induced plasminogen activation, resulting in 45% less plasmin generated after 30 minutes of activation at 40% (v/v) RBCs.

CONCLUSIONS

RBCs confer lytic resistance to fibrin resulting from modified fibrin structure and impaired plasminogen activation through a mechanism that involves eptifibatide-sensitive fibrinogen-RBC interactions.

Thrombocytosis: diagnostic evaluation, thrombotic risk stratification, and risk-based management strategies

Thrombocytosis is a commonly encountered clinical scenario, with a large proportion of cases discovered incidentally. The differential diagnosis for thrombocytosis is broad and the diagnostic process can be challenging. Thrombocytosis can be spurious, attributed to a reactive process or due to clonal disorder. This distinction is important as it carries implications for evaluation, prognosis, and treatment. Clonal thrombocytosis associated with the myeloproliferative neoplasms, especially essential thrombocythemia and polycythemia vera, carries a unique prognostic profile, with a markedly increased risk of thrombosis. This risk is the driving factor behind treatment strategies in these disorders. Clinical trials utilizing targeted therapies in thrombocytosis are ongoing with new therapeutic targets waiting to be explored. This paper will outline the mechanisms underlying thrombocytosis, the diagnostic evaluation of thrombocytosis, complications of thrombocytosis with a special focus on thrombotic risk as well as treatment options for clonal processes leading to thrombocytosis, including essential thrombocythemia and polycythemia vera.

Hematocrit and risk of venous thromboembolism in a general population. The Tromso study

BACKGROUND

Hematocrit above the normal range for the population, such as in primary or secondary erythrocytosis, predisposes to both arterial and venous thrombosis. However, little is known about the association between hematocrit and risk of venous thromboembolism in a general population.

DESIGN AND METHODS

Hematocrit and related hematologic variables such as hemoglobin, red blood cell count, mean corpuscular volume, and baseline characteristics were measured in 26,108 subjects, who participated in the Tromsø Study in 1994-1995. Incident venous thromboembolic events during follow-up were registered up to September 1(st), 2007.

RESULTS

There were 447 venous thromboembolic events during a median of 12.5 years of follow-up. Multivariable hazard ratios per 5% increment of hematocrit for the total population, adjusted for age, body mass index and smoking, were 1.25 (95% CI: 1.08-1.44) for total venous thromboembolism and 1.37 (95% CI: 1.10-1.71) for unprovoked venous thromboembolism. In category-based analyses, men with a hematocrit in the upper 20(th) percentile (>or=46% in men) had a 1.5-fold increased risk of total venous thromboembolism (95% CI: 1.08-2.21) and a 2.4-fold increased risk of unprovoked venous thromboembolism (95% CI: 1.36-4.15) compared to men whose hematocrit was in the lower 40(th) percentile. The risk estimates were higher for men than for women both in continuous and category-based analyses. The findings for hemoglobin and red blood cell count were similar to those for hematocrit, whereas mean corpuscular volume was not associated with venous thromboembolism. Conclusions Our findings suggest that hematocrit and related hematologic variables such as hemoglobin and red blood cell count are risk factors for venous thromboembolism in a general population.

Non ST-segment elevation myocardial infarction in patient with essential thrombocythemia

A 68-year-old woman presented with acute chest pain and a greatly increased platelet count. Cardiac catheterization revealed subtotal occlusion and a thrombus-like filling defect in the right coronary artery. The patient was successfully treated with intravenous tirofiban. Essential thrombocythemia was diagnosed based on bone marrow findings, clinical presentation and laboratory analysis. The relationship between intracoronary thrombus and essential thrombocythemia is discussed.

Spontaneous spinal epidural hematoma as the initial presentation of leukemia

We present a case of a 55-year-old male with progressive neurological deficits that appeared dramatically. MRI detected a spinal epidural hematoma at the cervicothoracic junction and blood tests showed leukocytosis, mild anemia, and thrombocytosis. Spontaneous spinal epidural hematoma (SSEH) as the initial presentation of leukemia was diagnosed. Urgent posterior decompression was performed after 28 h from acute onset of backache, and the patient experienced remarkable improvement in neurological findings.

Raised levels of CD39 in leucocytosis result in marked inhibition of ADP-induced platelet aggregation via rapid ADP hydrolysis

We observed previously that the extent of ADP-induced platelet aggregation in blood from patients with leucocytosis is markedly reduced. We obtained evidence that this is via enhanced ADP metabolism consequent to the high leucocyte count, and speculated that ecto-NTPDase CD39 on leucocytes may be involved. Here we have investigated the association between ADP-induced platelet aggregation, ADP metabolism and expression of ecto-NTPDase CD39 on leucocytes in patients with leucocytosis. Six patients with leucocytosis were compared with six normal controls. Platelet aggregation was measured using platelet counting. ADP metabolism was analysed by HPLC. CD39 on leucocytes from each volunteer and patient was measured by flow cytometry and is presented as the CD39 fluorescence index (CD39FI, the sum of the product of CD39 median fluorescence and cell number for each leucocyte subtype). Compared with the controls, all patients displayed markedly reduced platelet aggregation to ADP in whole blood, markedly enhanced metabolism of ADP to AMP in whole blood, and increased leucocyte CD39FI. The increased CD39FI was due to either a high number of CD39+ve lymphocytes or a high number of CD39+ve neutrophils. In contrast, the measures of aggregation and ADP metabolism performed in platelet-rich plasma from the patients were similar to those obtained for the controls. There was an inverse correlation between ADP-induced aggregation in whole blood and CD39FI, and between the time taken to achieve complete removal of ADP from blood and CD39FI. For two patients with very high CD39FI (60,000 cf 1500 for controls) ADP-induced aggregation was abolished. Reduced aggregation, enhanced ADP metabolism and a raised CD39FI returned to normal in one patient following successful chemotherapy. It is concluded that ADP-induced platelet aggregation in leucocytosis is reduced as a result of enhanced ADP metabolism due to raised levels of leucocyte-associated CD39.

Thrombophilia and risk of venous thrombosis in patients with cancer

Venous thrombosis is a common and severe complication in patients with cancer. We reviewed studies assessing whether a state of acquired or congenital thrombophilia influenced the risk of thrombosis in patients with cancer. The results are equivocal. However, the majority of studies were of limited size. The influence of thrombophilia in patients with cancer may be more difficult to demonstrate than in the general population, the risk of thrombosis due to cancer per se possibly outweighing the contribution of thrombophilic factors. Moreover, the results may depend on the genetic background of the population, the type of cancer, the type of thrombosis, and the chemotherapeutic treatment. Nevertheless, it appears that factor V Leiden or G20210A prothrombin gene mutation increases the risk of venous thromboembolism about 2- to 4-fold, compared with patients with cancer without either of these mutations. Similar results were observed for the occurrence of central venous catheter-associated thrombosis. Antiphospholipid antibodies and acquired resistance to activated protein C were frequently observed in patients with cancer and appeared to favor the occurrence of thrombosis. The role of hyperhomocysteinemia deserves further investigation. Since the clinical implications of these findings remain to be clarified, routine screening of cancer patients for thrombophilia cannot yet be recommended on the basis of these studies. Studies designed to assess the value of thromboprophylaxis in high-risk patients, including thrombophilic patients, with long-term central venous catheters may be valuable.

Circulating microemboli in patients with myeloproliferative disorders

Myeloproliferative disorders (MPD) are associated with an increased risk for thrombembolic events. In this study, we examined the prognostic value of transcranial Doppler (TCD) microemboli detection regarding clinical events and correlated TCD findings with results of blood cell counts and platelet flow cytometry to gain insight into the composition of circulating microemboli in these patients. In a cohort of 42 patients with MPD TCD microemboli detection was performed on a single occasion and correlated with thrombembolic events during a prospective follow up of 29.7 +/- 7.3 month. In all patients, a complete blood count and in 17 patients platelet flow cytometry were performed on the day of the TCD examination. Microembolic signals (MES) were recorded in 15 (35.7%) patients, however, without any correlation with the type of MPD, blood cell counts, or thrombembolic events [9 (21.4%)]. MES positive and negative patients did not differ regarding the levels of activated platelets, platelet microaggregates, or microparticles. We found a strong trend for higher rates of platelet-neutrophil conjugates in MES positive patients (P = 0.09). Detection of MES by TCD on a single occasion in MPD patients has only limited prognostic value. MES do not correlate with the type of MPD, nor blood cell counts. Flow cytometry suggests that MES in MPD may consist of platelet-neutrophil aggregates.

Coronary artery bypass grafting in idiopathic myelofibrosis: a case report

The concomitant presence of myeloproliferative disorders and the need for coronary artery bypass surgery is a surgical dilemma. Thrombosis and hemorrhage can cause difficult problems and might require different approaches during and after surgery. We report a patient who had idiopathic myelofibrosis and underwent a successful coronary artery bypass surgery.

The haematocrit and platelet target in polycythemia vera

Polycythemia vera (PV) is a chronic myeloproliferative disorder whose major morbidity and mortality are thrombohaemorragic events and progression to acute leukaemia or myelofibrosis. Whether the haematocrit and platelet count predict such complications remains unclear. The European Collaboration on Low-dose Aspirin in Polycythemia Vera prospective study included 1638 PV patients. A total of 164 deaths (10%), 145 (8.85%) major thrombosis and 226 (13.8%) total thrombosis were encountered during 4393 person-years follow-up (median 2.8 years). In time-dependent multivariable analysis, a haematocrit in the evaluable range of 40-55% was neither associated with the occurrence of thrombotic events, mortality nor with haematological progression in the studied population. The haematocrit of patients in the highest and lowest deciles at baseline was maintained within a narrow interval of haematocrit values ranging from 40% to 47% throughout follow-up. High platelet count was associated with a lower progression rate to acute leukaemia/myelofibrosis, whereas it had no significant relationship with thrombotic events or mortality. Our findings do not suggest that the range of haematocrit (<55%) and platelet counts (<600 x 10(9)/l) we encountered in our population had an impact on the outcome of PV patients treated by current therapeutic strategies.

Use of whole blood platelet lumi-aggregometry to optimize anti-platelet therapy in patients with chronic myeloproliferative disorders

Twenty-seven patients with chronic myeloproliferative disorders and in vitro evidence of platelet hyperactivity on whole blood platelet lumi-aggregometry were commenced on anti-platelet therapy comprising aspirin, clopidogrel, and/or odorless garlic and the studies were repeated to assess the efficacy of the therapeutic agent(s). Only 8 patients showed clear evidence of anti-platelet effect while receiving the standard low-dose (100 mg/day) aspirin therapy. Thirteen patients required a higher dosage of aspirin and/or an additional anti-platelet agent to achieve therapeutic adequacy. Lumi-aggregometry also proved useful to optimize therapy in the 6 patients who received clopidogrel or odorless garlic because of aspirin intolerance.

Thrombosis and haemorrhage in polycythaemia vera and essential thrombocythaemia

Despite decades of clinical and laboratory research, relatively little has been accomplished concerning the pathogenesis as well as the identification of risk factors for thrombosis and bleeding in myeloproliferative disorders. In polycythaemia vera, the pro-thrombotic effect of an elevated haematocrit is well established. In contrast, thrombocytosis per se has not been similarly incriminated in essential thrombocythaemia. In both conditions, advanced age and the presence of a prior event identify thrombosis-prone patients. There is increasing evidence to suggest an additional role by leucocytes that might partly explain the antithrombotic effects of myelosuppressive therapy. A substantial minority of affected patients display reduced levels of high molecular weight von Willebrand protein in the plasma during extreme thrombocytosis and it is believed that this might explain the bleeding diathesis of such patients. Recent controlled studies support the therapeutic value of hydroxyurea and aspirin in essential thrombocythaemia and polycythaemia vera, respectively. The current communication will address the incidence, phenotype, pathogenesis, risk factors, prevention, and treatment of both thrombosis and haemorrhage in these disorders.

Functional and morphological cardiac changes in myeloproliferative disorders (clinical study)

PURPOSE

Cardiac involvement is not well defined in myeloproliferative disorders (MPD). The purpose of this study was to evaluate the cardiac involvement by transthoracic echocardiography in MPD.

MATERIALS AND METHODS

The study groups were 36 patients (mean age: 58+/-15 years, 20 female and 16 male) with MPD and 30 age-matched healthy controls. MPD group included 15 essential thrombocythemia (ET), eight chronic phase chronic myelogenous leukemia (CML), seven idiopathic myelofibrosis (MF) and six polcythemia vera patients.

RESULTS

Valvular regurgitations were present in 14 patients (39%) and eight controls (27%), (P>0.05). Mitral regurgitation (MR) was more prominent in CML compared to controls (P=0.044). The rates of annular calcifications, valvular thickening, and vegetation like lesions were not different between MPD and control groups. Pulmonary hypertension (PHT) was present in six (17%) patients, but none of the controls (P=0.021). The rates of PHT in CML and MF were significantly higher than controls (P<0.05). The rate of PHT was not different in-between MPD patients with and without thromboembolic events, however, in MPD cases with thromboembolic events PHT was more common compared to controls (P=0.037).

CONCLUSION

This study showed that valvular lesions were not more prevalent in MPD. PHT was the most prominent cardiac pathology in MPD (especially in CML, MF and thromboembolic events subgroups) compared to controls. Further evaluation of the cardiac changes in MPD subgroups with extended studies including trans-oesophageal echocardiography and longer follow-up periods would be appropriate.

Anagrelide is effective in treating patients with hydroxyurea-resistant thrombocytosis in patients with chronic myeloid leukemia

We report phase II trial results of the use of oral anagrelide hydrochloride for treating 38 patients with hydroxyurea (HU)-resistant thrombocytosis accompanying chronic myeloid leukemia (CML). Anagrelide's efficacy was well established during a phase II study of more than 400 patients with one of the four myeloproliferative disorders: essential thrombocythemia, polycythemia, idiopathic myelofibrosis, and CML. In the last subgroup, there were 114 CML patients with significant thrombocytosis treated with anagrelide. Out of these patients, 38 had symptoms of thrombosis or hemorrhage and had thrombocytosis resistant to HU. They were then treated with anagrelide at an initial dose of 2.0 mg/day, followed by modifications based upon response and toxicity. In all, 71% of these patients responded with platelet reductions of more than 50% in a median time of approximately 4 weeks. The response rate was not influenced by age, gender, or prior thrombosis or hemorrhage. Importantly, the response rate to anagrelide in patients refractory to prior HU was essentially the same as that of the other 76 CML patients. Treatment with anagrelide was well tolerated and without undue toxicity. Reduction of excessive platelet counts by anagrelide sometimes occurring in CML may lead to the prevention of thrombohemorrhagic complications occurring in this clinical setting and is relevant even in those patients in whom imatinib mesylate is primary therapy.

Propensity for hemorrhage and thrombosis in chronic myeloproliferative disorders

Polycythemia vera (PV) and essential thrombocythemia (ET) are two myeloproliferative disorders (MPDs) with frequent thrombotic and hemorrhagic complications. Thrombosis is often the cause of mortality in PV and ET; hemorrhage occurs more commonly in idiopathic myelofibrosis patients, but is rarely fatal. Thromboses may occur in arteries or veins. Splanchnic, portal, hepatic, and splenic vein thromboses are not uncommon and thrombosis is also thought to cause placental vascular insufficiency and fetal wastage during pregnancies in MPD patients. These complications may result because of altered interactions between platelets, white blood cells, or endothelial cells, due to either altered receptor expression, receptor-ligand interactions, or signaling events. Age, leukocytosis, increased hematocrit, and a history of thrombotic events are risk factors for thrombosis. In determining a link between clonality and thrombosis using X-chromosome inactivation patterns in patients with ET, those who were polyclonal were less likely to experience thromboses. The search for hypercoagulability in these patients led to identification of changes in the expression patterns of coagulation proteins from the coagulation cascade. Mutations in factor V Leiden were examined and the incidence of mutations did not vary between normal and MPD patients. However, mutations in factor V Leiden were found to be risk factors for venous thrombotic events. Similarly, presence of a prothrombin gene mutation showed a higher risk for venous thromboembolic events. Proteolyzed thrombospondin appeared to contribute to hypercoagulability, and acquired von Willebrand factor disorder gave rise to hemorrhagic complications. These findings provide several potential reasons for thrombotic and hemorrhagic complications in MPD patients. Therefore, the best therapy for these patients is reduction of their platelet counts to less than 450,000/microL and close regulation of their hematocrits. The role of leukocytosis in bleeding or hemorrhage in this population remains to be elucidated.

Hemostatic gene polymorphisms and the prevalence of thrombotic complications in polycythemia vera and essential thrombocythemia

Patients with polycythemia vera and essential thrombocythemia are at risk for thrombotic and bleeding complications. Currently, no diagnostic test can predict thrombohemorrhagic complications. In a prospective study of 86 patients with polycythemia vera (43 patients) or essential thrombocythemia (43 patients), we examined the possible role of polymorphisms of platelet adhesion receptors [glycoprotein (GP) Ibalpha, GPIa, GPIIIa) and clotting factor II (prothrombin's G20210A mutation) and clotting factor V (Leiden mutation) in determining the risk of thrombotic or bleeding complications. Except for an association between vasomotor symptoms and prothrombin mutation (P < 0.001), no significant correlation between polymorphism of clotting factors and thrombohemorrhagic complications was identified. When the entire patient cohort was considered, the polymorphisms of platelet adhesion receptors were not associated with the risk for thrombotic or bleeding complications. However, among patients with polycythemia vera, the presence of the PlA2 allele of GPIIIa was associated with an increased risk of arterial thrombosis. In view of previous studies linking the presence of the PlA2 allele of GPIIIa to a higher risk for coronary artery thrombosis, our data have physiologic relevance. However, they need to be confirmed in a larger study.