Prevalence of thromboembolic events among 8,860 patients with thalassaemia major and intermedia in the Mediterranean area and Iran

Abstract

SummaryBeta-thalassaemia isa congenital haemolytic anaemia characterized by partial (intermedia, TI) or complete (major, TM) deficiency in the production of β-globin chains.The primary aim of this study was to determine the prevalence of thromboembolic events in patients with β-thalassaemia.To achieve this,a multiple-choice questionnaire was sent to 56 tertiary referral centres in eight countries (Lebanon, Italy, Israel, Greece, Egypt, Jordan, Saudi Arabia and Iran), requesting specific information on patients who had experienced a thromboembolic event.The study demonstrated that thromboembolic events occurred ina clinically relevant proportion (1.65%) of 8,860 thalassaemia patients (TI – 24.7% or TM – 75.3%) from the Mediterranean and Iran. Thromboembolism occurred 4.38 times more frequently in TI thanTM (p<0.001), with more venous events occurring inTI and more arterial events occurring in TM.Thrombosis in thalassaemia was also more common in females, splenectomized patients and those with profound anaemia (haemoglobin <9 g/dl). Due to the increased risk of thromboembolic events, the rationale for splenectomy should perhaps be re-assessed and the role of transfusion therapy for the prophylaxis of thrombosis, among other complications, be evaluated prospectively.

Thalassemic erythrocytes release microparticles loaded with hemichromes by redox activation of p72Syk kinase

“…12 Circulating MP can be very noxious in different clinical settings such as acute coronary syndromes, atherosclerosis, post-transfusional acute respiratory distress syndrome, diabetes mellitus, systemic inflammatory disease and disseminated intravascular coagulation. 10,12,36,39,40 MP originating from RBC membranes have also been considered a major cause of premature atherosclerosis described in TI patients. 13 The mechanisms responsible for the generation of MP appear very complex in different cell types 32 and very little is known about thalassemic RBC.…”

“…The rates of almost all complications are significantly higher in splenectomized patients than in nonsplenectomized patients. 36 The development of these complications has been attributed to the presence of high platelet counts and/or to an increased number of pathological RBC with potentially thrombogenic, negatively charged membranes. Thrombin generation is significantly higher in splenectomized TI patients than in control subjects or patients who have not undergone splenectomy.…”

“…10,12,36,39,40 MP originating from RBC membranes have also been considered a major cause of premature atherosclerosis described in TI patients. 13 The mechanisms responsible for the generation of MP appear very complex in different cell types 32 and very little is known about thalassemic RBC.…”

Heart disease in thalassemia intermedia: a review of the underlying pathophysiology

“…A recently published multinational study of 8,860 thalassaemia patients from the Mediterranean region and Iran showed that thromboembolic events were 4.38 times more frequent in TI than in TM, and were particularly prevalent in splenectomized patients and patients with profound anaemia (hemoglobin level <9 g/dL). 41 Ischemic strokes have also been observed in combination with cardiac valvular lesions resulting from elastic tissue defect and/or atrial fibrillation. 29 However, thrombosis may be a sub-clinical process and may remain undetected.…”

Hypercoagulability and thrombotic complications in hemolytic anemias

“…1 In addition to increased thrombin and fibrin generation, increased tissue factor activity, and increased platelet activation (Figure 1), patients with hemolytic anemias manifest thrombotic complications, including venous thromboembolism, in situ pulmonary thrombosis and stroke. [1][2][3][4][5][6][7] Furthermore, the risk of thromboembolic complications appears to be higher following splenectomy. 1,3,6 The mechanism of coagulation activation in hemolytic anemias is likely multifactorial.…”