Date Published: December 29, 2012
Publisher: Hindawi Publishing Corporation
Author(s): Nahid Ashjazadeh, Sajad Emami, Peyman Petramfar, Ehsan Yaghoubi, Mehran Karimi.
Introduction. Patients with β-thalassemia intermedia have a higher incidence of thromboembolic events compared to the general population. Previous studies have shown that patients with sickle cell disease, who are also prone to ischemic events, have higher intracranial arterial blood flow velocities measured by transcranial Doppler sonography (TCD). The aim of this study is to evaluate intracranial arterial flow velocities in patients with β-thalassemia intermedia and compare the results with those found in healthy subjects. Methods. Sixty-four patients with β-thalassemia intermedia and 30 healthy subjects underwent transcranial Doppler sonography. Results. Significantly higher flow velocities were found in intracranial arteries of patients compared to controls (P = 0.001). Previously splenectomized patients with thrombocytosis showed higher flow velocities than nonsplenectomized patients without thrombosis. Conclusion. The increased flow velocities in patients with β-thalassemia intermedia may point to a higher risk of ischemic events. Preventive measures such as blood transfusion or antiplatelet treatment may be beneficial in these patients.
Patients with β-thalassemia intermedia (B-TI) seem to show higher rates of thromboembolic events than individuals without thalassemia or patients with β-thalassemia major,in particular if they have been splenectomized . It is estimated that 4% of patients with β-thalassemia intermedia will experience a thromboembolic event . Previous splenectomy and thrombocytosis and/or platelet abnormalities are major factors associated with thromboembolic events in patients with β-thalassemia intermedia [1, 3, 4], and ischemic stroke is increasingly recognized as one of the most devastating complications of this disease .
This is a case-control study conducted in a tertiary outpatient clinic affiliated with Shiraz University of Medical Sciences, Southern Iran, for a period of one year during 2009. Consecutive patients older than 15 years of age with confirmed β-thalassemia intermedia by complete blood count and hemoglobin electrophoresis who were referred to an outpatient thalassemia clinic enrolled in the study. Diagnosis of B-TI was based on complete blood count, hemoglobin electrophoresis, and initial hemoglobin (Hb) level of 7 gr/dL, and age of diagnosed anemia was after 2. All of them were transfusion independent. Patients were recruited at a routine follow-up visit with a hematologist in the clinic. Exclusion criteria were a history of diabetes mellitus, hypertension, ischemic heart disease, thrombosis, previous cerebrovascular disease, sickle cell anemia, or inadequate temporal window for TCD. The study was approved by the Ethics Committee of Shiraz University of Medical Sciences (no. 2885), and written informed consent to participate was obtained from all patients or their first-degree families. All patients were receiving folic acid (5 mg/day) and hydroxyurea (8–15 mg/kg/day).
After applying the inclusion and exclusion criteria, 64 patients with β-thalassemia intermedia and 30 healthy subjects were recruited. There were no significant differences between patients and controls according to sex (male: 40.6% versus 53.3%; P = 0.251) or age (23.6 ± 5.2 versus 25.4 ± 5.4; P = 0.001). Mean velocities of all mentioned vessels were measured in all patients and control subjects, and no missing vessel was detected. Among the patients, 54.7% (35/64) had undergone splenectomy, and 9.4% (6/64) had received a blood transfusion once or twice a year before the study. None of the control subjects had received transfusion. In patients, mean Hb level was 9.3 ± 1.2 g/dL (range 6.9–12.3), mean white blood cell count was 8873 ± 2004/dL (range 4900–13800), and mean platelet count was 523 × 103 ± 219 × 103/dL (range 188 × 103–1035 × 103). There were no significant differences in age, white blood cell count, or Hb level between splenectomized and nonsplenectomized patients (P > 0.05). Mean platelet count was significantly higher in patients who had undergone splenectomy (696 × 103 ± 129 × 103/dL versus 315 × 103 ± 78 × 103/dL; P = 0.001). All the splenectomized patients had thrombocytosis, and none of the nonsplenectomized patients had thrombocytosis. Platelet count correlated with blood flow velocity in the right MCA (r = 0.291, P = 0.020), left MCA (r = 0.366, P = 0.003), left ACA (r = 0.258, P = 0.040), right PCA (r = 0.270, P = 0.031), left PCA (r = 0.267, P = 0.033), and BA (r = 0.300, P = 0.016). There were no correlations between platelet count and blood flow velocities of the other arteries (P > 0.05). Mean intracranial arterial flow velocities in β-thalassemia intermedia patients with or without splenectomy are shown in Table 1. There were no significant differences in white blood cell count, Hb levels, or platelet count between patients who had undergone transfusion and those who had not (P > 0.05).
In this study, higher blood flow velocities were found in all intracranial arteries of our patients. Flow velocity was higher in most arteries of splenectomized patients compared to nonsplenectomized patients, especially in the anterior circulation. In addition, there was a correlation between platelet count and flow velocities.