Low Incidence of Cardiac Siderosis in Heavily Iron Overloaded Egyptian Thalassemics.

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) technology can measure cardiac iron deposition directly using the magnetic relaxation time T2*. This allows earlier diagnosis and treatment and help to reduce mortality from this cardiac affection.

89 β thalassemia patients (10 to 43 years, mean age of 20.78±6.36) were recruited in this study. All patients were receiving chelation therapy of subcutaneous desferroxamine. Evaluation of hemosiderosis was based on CMR, liver magnetic resonance R2 and serum ferritin.

T2* values ranged between 4.3 to 53.8 ms with a mean of 28.50±11.74 ms among our study group. The left ventricular ejection fraction (LVEF) as measured by CMR ranged between 55 and 78%; mean=67.66±4.69%.and liver iron concentration (LIC) ranged between 1.5 to 56 mg/g dry weight with a mean of 26.13±13.37 mg/g. Serum ferritin varied among our study group from 533 to 22363ng/ml; mean=4514.27±2847.58ng/ml with 83.15% above 2500ng/ml. The prevalence of myocardial siderosis (T2*<20ms) among our patients was 22/89 patients (24.7%) aged 20.86±7.54 years with a mean T2* value of 12.718±4.36ms and LVEF of 68.59 ±5.84%. LIC and serum ferritin results were 30.85±13.48 mg/g and 6122.86±4185.67ng/ml respectively. There was no correlation between T2* results and the age, LVEF, LIC and serum ferritin of this group (P=0.651, P=0.085, P=0.999 and P=0.627 respectively). Those patients with severe cardiac siderosis (T2*<10ms) constituted 7/89 (7.9%) with a mean age of 18.43±4.35 years. Although these patients had a mean T2* of 7.8±1.73 ms, the LVEF value was 65.14±6.20 % and only one patient had clinical cardiac disease (T2*=4.3 ms and LVEF =55%). LIC and serum ferritin results were 29.84±16.99mg/g and 7202.14±6953.79ng/ml respectively. In this group of severe cardiac siderosis, T2* was not correlated to age (P=0.5), LVEF (P=0.144), LIC (P=0.969) and serum ferritin (P=0.818).

Low prevalence of myocardial siderosis in the Egyptian thalassemic patients in spite of the very high serum ferritin. In severely iron overloaded patients the cardiac function was not affected. T2* is the best test that can identify at risk patients who can be treated with optimization of their chelation protocols. The possibility of a genetic component for the susceptibility of cardiac iron loading in our population should be considered.

No relevant conflicts of interest to declare.