Abstract
Betathalassemic patients demonstrate an increased rate of extracardiac vascular complications, but very low prevalence for coronary artery disease. Computed tomography (CT) achieves excellent tissue characterization, with high spatial resolution and has developed as a gold standard for noninvasive angiography and calcium score assessment. Methods. We examined 7 patients with major beta-thalassemia and 7 patients who had an indication for cardiac CT for resting ECG changes, without symptoms of angina pectoris. We investigated the coronary atherosclerosis by assessing the coronary artery calcium (CAC) and arterial stifness. Usual tests and echocardiography measurement were performed. Cardiac computed tomography determined left ventricular mass, left ventricular ejection fraction (LVEF), coronary calcium score and coronary anatomy. An analysis of myocardial density was also performed. Artery stiffness was assessed by the cardio ankle vascular index (CAVI). Results. Arterial stiffness index in betathallasemic group was higher than control group, R-CAVI index was 6.21± 0.49 vs 5.65±0.37 and L-CAVI index was 6.21± 0.38 vs 5.71±0.31. The assessment of systolic function by echocardiography and cardiac CT examination in the 2 groups, shows that the LVEF in the betathallasemic group was significantly lower than in the control group, which means that some patients already had cardiomyopathy. LV myocardial mass was significantly higher in the group with beta-thalassemia, which is explained by the appearance of myocardial remodeling. The calcium score in patients with major beta-thalassemia was 0 and 8,5± 5,9 in the control group. Only 3 patients (42,8%) in the control group had a calcium score > 10U. No atherosclerotic lesions were observed in patients with major beta-thalassemia, whereas the control group showed mild coronary atherosclerotic lesions. If myocardial density can be determined, calcium or iron deposits can be detected in the myocardium. In patients with beta-thalassemia, the density of the myocardium was higher, both in the left ventricle (49.29 8.87±HU) and in the septum (56.71± 8.1 HU). Calculation of Pearson’s correlation coefficient revealed a good association between CT and echocardiography, reproducibility of CT was significantly higher on an intra-observer level for LVEF and LV Mass. Conclusions: Patients with β–thalassemia major have a similar calcium score compared to control subjects, but they have an increase in arterial stiffness. However, zero frequencie of coronary heart disease, denotes coronary protection mechanisms in thalassemia, so future research should focus on the anti-atherogenic potential of blood lipids at these patients. The ability of cardiac tomography to detect calcifications and changes in myocardial density should be valued, as it can be a good tool for establishing the diagnosis of cardiomyopathy by iron loading.
Highlights
Beta-thalassemia major is an autosomal recessive disease caused by reduced synthesis of β-globin chains, with an excess of α-globin chains, leading to inefficient erythropoiesis and chronic hemolytic anemia[1] In major beta-thalassemia, iron overload occurs in various organs and tissues, leading most frequently to cardiovascular complications
Iron chelators with deferoxamine in patients with coronary heart disease improve endothelium-dependent vasodilation, suggesting that iron contributes to nitric oxide dysfunction in atherosclerosis
This paper showed that the patients with major beta-thalassemia have a similar calcium score compared to the control subjects, but they showed an increase in arterial stiffness
Summary
Beta-thalassemia major is an autosomal recessive disease caused by reduced synthesis of β-globin chains, with an excess of α-globin chains, leading to inefficient erythropoiesis and chronic hemolytic anemia[1] In major beta-thalassemia, iron overload occurs in various organs and tissues, leading most frequently to cardiovascular complications. Iron overload increases arterial stiffness and generates left ventricular remodeling in patients with major β-thalassemia, which over time leads to the occurrence of mechanical cardiac dysfunction [2]. Vascular complications in these patients have been attributed to increased lipid peroxidation products, but the mechanism of atherogenesis remains controversial [3]. Computed tomography (CT) achieves excellent tissue characterization, with high spatial resolution and has developed as a gold standard for noninvasive angiography and calcium score assessment. Less widely used for functional analysis, its ability to accurately assess left ventricular (LV) function has been known for many years [4] and is recommended when other imaging techniques, especially magnetic resonance are not available
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