Myocardial
siderosis in
thalassemia major remains the leading cause of death in developing countries. Once
heart failure develops, the outlook is usually poor with precipitous deterioration and death. Cardiovascular magnetic resonance (CMR) can measure cardiac
iron deposition directly using the magnetic relaxation time T2*. This allows earlier diagnosis and treatment and helps to reduce mortality from this cardiac affection. This study aims to determine the prevalence of cardiac
siderosis in Egyptian patients who are heavily
iron loaded and its relation to liver
iron concentration, serum
ferritin, and left ventricular ejection fraction. Eighty-nine β-
thalassemia patients receiving
chelation therapy (mean age of 20.8 ± 6.4 years) were recruited in this study. Tissue
iron levels were determined by CMR with cardiac T2* and liver R2*. The mean ± standard deviation (range) of cardiac T2* was 28.5 ± 11.7 ms (4.3 to 53.8 ms), the left ventricular ejection fraction (LVEF) was 67.7 ± 4.7 % (55 to 78 %), and the liver
iron concentration (LIC) was 26.1 ± 13.4 mg Fe/g dry weight (dw) (1.5 to 56 mg Fe/g dw). The mean serum
ferritin was 4,510 ± 2,847 ng/ml (533 to 22,360 ng/ml), and in 83.2 %, the serum
ferritin was >2,500 ng/ml. The prevalence of myocardial
siderosis (T2* of <20 ms) was 24.7 % (mean age 20.9 ± 7.5 years), with mean T2* of 12.7 ± 4.4 ms, mean LVEF of 68.6 ±5.8 %, mean LIC of 30.9 ± 13 mg Fe/g dw, and median serum
ferritin of 4,996 ng/ml. There was no correlation between T2* and age, LVEF, LIC, and serum
ferritin (P = 0.65, P = 0.085, P = 0.99, and P = 0.63, respectively). Severe cardiac
siderosis (T2* of <10 ms) was present in 7.9 %, with a mean age of 18.4 ± 4.4 years. Although these patients had a mean T2* of 7.8 ± 1.7 ms, the LVEF was 65.1 ± 6.2 %, and only one patient had
heart failure (T2* of 4.3 ms and LVEF of 55 %). LIC and serum
ferritin results were 29.8 ± 17.0 mg/g and 7,200 ± 6,950 ng/ml, respectively. In this group of severe cardiac
siderosis, T2* was also not correlated to age (P = 0.5), LVEF (P = 0.14), LIC (P = 0.97), or serum
ferritin (P = 0.82). There was a low prevalence of myocardial
siderosis in the Egyptian
thalassemia patients in spite of very high serum
ferritin and high LIC. T2* is the best test that can identify at-risk patients who can be managed with optimization of their
chelation therapy. The possibility of a genetic component for the resistance to cardiac
iron loading in our population should be considered.