Myocardial infarction as a thrombotic complication of essential thrombocythemia and polycythemia vera

Primary polycythaemia: A neglected risk factor

In this case series, we report a 32-year-old male patient with myocardial infarction and 45-year-old female with portal vein thrombosis with splenic infarcts, which were the initial manifestations of polycythaemia vera. The awareness of myeloproliferative disorders as a possible underlying disease-especially in young patients presenting with myocardial infarction and portal venous thrombosis-is crucial for clinical management, as a missed diagnosis can worsen the patients' further prognosis.

Inflammation as a cause of acute myocardial infarction in patients with myeloproliferative neoplasm

Myeloproliferative neoplasms (MPN) are a group of diseases characterized by the clonal proliferation of hematopoietic progenitor or stem cells. They are clinically classifiable into four main diseases: chronic myeloid leukemia, essential thrombocythemia, polycythemia vera, and primary myelofibrosis. These pathologies are closely related to cardio- and cerebrovascular diseases due to the increased risk of arterial thrombosis, the most common underlying cause of acute myocardial infarction. Recent evidence shows that the classical Virchow triad (hypercoagulability, blood stasis, endothelial injury) might offer an explanation for such association. Indeed, patients with MPN might have a higher number and more reactive circulating platelets and leukocytes, a tendency toward blood stasis because of a high number of circulating red blood cells, endothelial injury or overactivation as a consequence of sustained inflammation caused by the neoplastic clonal cell. These abnormal cancer cells, especially when associated with the JAK2V617F mutation, tend to proliferate and secrete several inflammatory cytokines. This sustains a pro-inflammatory state throughout the body. The direct consequence is the induction of a pro-thrombotic state that acts as a determinant in favoring both venous and arterial thrombus formation. Clinically, MPN patients need to be carefully evaluated to be treated not only with cytoreductive treatments but also with cardiovascular protective strategies.

Acute myocardial infarction in myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) are a heterogeneous group of hematologic malignancies characterized by an abnormal proliferation of cells of the myeloid lineage. Affected individuals are at increased risk for cardiovascular and thrombotic events. Myocardial infarction (MI) may be one of the earliest clinical manifestations of MPNs or may be a thrombotic complication that develops during the natural course of the disease. In the present review, we examine the epidemiology, pathogenesis, clinical presentation, and management of MI in MPNs based on the available literature. Moreover, we review potential biomarkers that could mediate the MI-MPNs crosstalk, from classical biochemical tests, e.g., lactate dehydrogenase, creatine kinase and troponins, to pro-inflammatory cytokines, oxidative stress markers, and clonal hematopoiesis.

A Young Adult With Essential Thrombocythemia Presenting as Myocardial Infarction

Essential thrombocythemia (ET) is a myeloproliferative neoplasm involving the clonal proliferation of platelets. It is Philadelphia negative and is associated with Janus kinase 2 (JAK2), calreticulin (CALR), or myeloproliferative leukemia virus oncogene (MPL) mutations. The resultant platelets have quantitative and qualitative defects, making them more sticky and prone to thromboembolism. However, ET does not only affect platelet survival, it also has a low leukemogenic potential. It's more common in the elderly, 60 years or more, but can be seen in all age groups, including children. Patients with ET have an increased risk of vascular events like hemorrhage and thromboses like cerebrovascular events, myocardial infarction, superficial thrombophlebitis, deep vein thrombosis, and pulmonary embolism. Cardiovascular risk factors like hypertension, diabetes, and smoking can lead to increased thromboembolism and atherosclerosis. The management of ET focuses primarily on the prevention of thrombosis and hemorrhage. It involves cardiovascular risk management and antiplatelet and cytoreductive therapy according to the risk stratification. Low-risk ET patients are treated with low-dose aspirin, and high-risk ET patients are treated with cytoreductive therapy with hydroxyurea. Interferon (IFN) and anagrelide are reserved for young patients or pregnant women. This case report discusses a 40-year-old male, a known smoker presenting with myocardial infarction and left anterior descending artery (LAD) blockage without any prior history. His high platelets and the relative absence of cardiovascular risk factors helped reach the diagnosis, and bone marrow analysis and mutation analysis confirmed the diagnosis. The patient was started on hydroxyurea, which decreased the total platelet count. 

Vascular Endothelial Dysfunction in Myeloproliferative Neoplasms and Gene Mutations

Essential thrombocythemia (ET) and polycythemia vera (PV), are common Philadelphia-negative myeloproliferative neoplasms (MPN). Patients with MPN have a high rate of cardiovascular complications and often have acquired JAK2V617F and CALR genetic mutations. In this study, we aimed to analyze vascular endothelial function in patients with MPN.We evaluated 27 outpatients, including 10 patients diagnosed with MPN, flow-mediated dilatation (FMD), and nitroglycerin-mediated dilation (NMD), between September 2014 and August 2016. We measured serum adiponectin, which protects vascular endothelial function, and serum asymmetric dimethyl arginine (ADMA), which inhibits the production of adiponectin. The presence or absence of JAK2V617F and CALR mutations was evaluated in patients with MPN.Venous thrombosis was observed more frequently in patients with MPN than in those without. Seven MPN patients were diagnosed with PV, and 3 MPN patients were diagnosed with ET. JAK2V617F and CALR mutations were found in 5 and 3 MPN patients, respectively. FMD was significantly lower in JAK2V617F-positive MPN patients than in JAK2V617F-negative MPN patients, although NMD, adiponectin, and ADMA were similar in both groups. Adiponectin levels were higher and ADMA levels were lower in CALR-positive MPN patients than in CALR-negative MPN patients. There was no difference in FMD and NMD prevalence between the 2 groups. Furthermore, we had 3 representative MPN patients who were complicated with coronary spasm, possibly caused by MPN-related endothelial dysfunction.We found that patients with MPN presented with endothelial dysfunction, which was related to the presence of genetic mutations and was sometimes associated with cardiovascular disease.

Pathogenesis of cardiovascular events in BCR-ABL1-negative myeloproliferative neoplasms

Thrombosis, both in arterial and venous territories, is the major complication of myeloproliferative neoplasms and is responsible for a high rate of morbidity and mortality. The currently accepted risk factors are an age over 60 years and a history of thrombosis. However, many complex mechanisms contribute to this increased prothrombotic risk, with involvement of all blood cell types, plasmatic factors, and endothelial cells. Besides, some cardiovascular events may originate from arterial vasospasm that could contribute to thrombotic complications. In this review, we discuss recent results obtained in mouse models in the light of data obtained from clinical studies. We emphasize on actors of thrombosis that are currently not targeted with current therapeutics but could be promising targets, i.e, neutrophil extracellular traps and vascular reactivity.

Erythrocyte-derived microvesicles induce arterial spasms in JAK2V617F myeloproliferative neoplasm

Arterial cardiovascular events are the leading cause of death in patients with JAK2V617F myeloproliferative neoplasms (MPNs). However, their mechanisms are poorly understood. The high prevalence of myocardial infarction without significant coronary stenosis or atherosclerosis in patients with MPNs suggests that vascular function is altered. The consequences of JAK2V617F mutation on vascular reactivity are unknown. We observe here increased responses to vasoconstrictors in arteries from Jak2V617F mice resulting from a disturbed endothelial NO pathway and increased endothelial oxidative stress. This response was reproduced in WT mice by circulating microvesicles isolated from patients carrying JAK2V617F and by erythrocyte-derived microvesicles from transgenic mice. Microvesicles of other cellular origins had no effect. This effect was observed ex vivo on isolated aortas, but also in vivo on femoral arteries. Proteomic analysis of microvesicles derived from JAK2V617F erythrocytes identified increased expression of myeloperoxidase as the likely mechanism accounting for their effect. Myeloperoxidase inhibition in microvesicles derived from JAK2V617F erythrocytes suppressed their effect on oxidative stress. Antioxidants such as simvastatin and N-acetyl cysteine improved arterial dysfunction in Jak2V617F mice. In conclusion, JAK2V617F MPNs are characterized by exacerbated vasoconstrictor responses resulting from increased endothelial oxidative stress caused by circulating erythrocyte-derived microvesicles. Simvastatin appears to be a promising therapeutic strategy in this setting.

Atypical Myocardial Infarction with Apical Thrombus and Systemic Embolism: A Rare Presentation of Likely JAK2 V617F-Positive Myeloproliferative Neoplasm

A few types of myeloproliferative neoplasms may be significant for Janus-associated kinase 2 mutation, JAK2 V617F, including polycythemia vera, essential thrombocythemia, and primary myelofibrosis. The prevalence of JAK2 mutation is low in the general population but higher in patients with myeloproliferative neoplasms. Some patients with JAK2 V617F-positive essential thrombocythemia are asymptomatic, but others may develop hemorrhagic or thromboembolic complications. Thromboembolism may occur in vessels of high flow organs like the heart and, thereby, present as myocardial infarction. Nonetheless, these patients are usually symptomatic with complaints of chest pain, for example. Atypical (asymptomatic) myocardial infarction with mild thrombocytosis may be the first clue for possible essential thrombocythemia with JAK2 V617F. In this report, we discuss a case of atypical (asymptomatic) myocardial infarction with secondary thromboembolism in a patient positive for JAK2 V617F with a likely myeloproliferative neoplasm.

A case of simultaneous acute cardio-cerebral infarction in a woman with essential thrombocythemia

Essential thrombocythemia (ET) can cause arterial embolism. Patients with arterial thrombosis usually have additional risk factors, such as smoking and hypertension. We report a 70-year-old woman with ET who had no risk factors, except for age. Cranial magnetic resonance imaging showed fresh lacunar infarction in several lobes. Electrocardiography showed ST-segment elevation in leads II, III, and aVF. Coronary angioplasty and stenting were successfully performed. We checked the bone marrow and performed genetic testing. The Janus kinase 2 (JAK2) V617F gene mutation was found. This case was a rare initial presentation of previously undiagnosed ET with embolism of cardiovascular and cerebral vessels. Anti-platelet drugs and hydroxyurea were used to prevent further thrombosis in the coronary and cerebral arteries.

Essential thrombocythemia presenting as acute coronary syndrome: case reports and literature review

For the patients with essential thrombocythemia (ET), systemic thrombosis presents as one of the most dangerous complications. It's been widely accepted that acute coronary syndrome (ACS) is a kind of thrombotic diseases. However, there are very few case reports about ET first presenting as ACS. For some patients diagnosed as ACS, but without markedly elevated platelet, underlying ET was missed. And there are some controversies in the principles and target of treatment in those patients. We reported three cases of ACS, in which the patients who did not have common risk factors for coronary artery diseases and presented only mild atherosclerotic stenosis during coronary angiography, one of which had recurrent coronary artery thrombosis. Noticing their elevated blood platelet level and characteristics in angiography, diagnosis of ET was made according to bone marrow morphology and genetic tests. Although they had only mild thrombocytosis, we applied intensive treatment with dual anti-platelet therapy combined with cytoreduction in addition to early coronary intervention, having satisfying outcomes. During the diagnosis and treatment of ACS, if patients present thrombocytosis, but lack common coronary disease risk factors and thrombotic coronary artery occlusion, cardiologists should search for possible ET as an underlying cause of thrombotic coronary event. All those patients were high-risk according to ET risk stratification. Treatment of cytoreduction in combination with anti-thrombosis therapy and revascularization are beneficial. Treatment aims at the target of complete response with platelet count below 400 × 10⁹/L.

Acute Coronary Syndromes in Patients with Hematological Disorders

Hematological conditions can lead to serious disturbances in blood rheology, being frequently associated with increased systemic inflammation and increased risk of bleeding. The imbalance between coagulation and thrombolytic factors in patients with acute coronary syndromes may lead to undesirable outcomes, and the success of emergency coronary angioplasty or by-pass grafting may be altered by increased bleeding in coagulopathies such as hemophilia. This paper intends to review the present knowledge in the field of acute coronary syndromes in subjects with hematological and onco-hematological disorders such as thrombotic thrombocytopenic purpura, immune thrombocytopenic purpura, von Willebrand disease, hemophilia, polycythemia vera, erythrocyte disorders, myelodysplastic syndrome, leukemia, lymphoma or myeloma.