Abstract
BACKGROUND: Cardiac failure from myocardial iron deposition is a severe complication in patients with transfusion-related iron overload. Progressive heart damage from iron overload can cause left ventricular systolic and diastolic dysfunction in patients with hematologic disorders. Since nontransfused patients with sickle cell anemia (SCA) have a high incidence of diastolic dysfunction, we investigated the relationships among transfusional iron burden, myocardial iron deposition, and diastolic ventricular dysfunction by T2*-MRI and tissue Doppler echocardiography in iron-overloaded children with SCA. PROCEDURE: Children (> or =7 years) with SCA and iron overload (serum ferritin >1,000 ng/ml or > or =18 lifetime transfusions) were eligible. Serum ferritin and hepatic iron content (HIC) were measured and participants underwent nonsedated T2*-MRI of the heart, echocardiogram, electrocardiogram, and multi-uptake gated acquisition (MUGA) scan. Age-matched normative echocardiographic data were used for comparison. RESULTS: Among 30 children with SCA (median age, 13 years) and iron overload, mean (+/-SD) HIC and serum ferritin were 10.8 mg Fe/g (+/-5.9 mg Fe/g) and 3,089 ng/ml (+/-2,167 ng/ml), respectively. Mean T2*-MRI was 33 msec (+/-7 msec, range, 22-49). Echocardiography showed a high prevalence of diastolic dysfunction (77% and 45% abnormally low mean mitral annular velocity and mean tricuspid annular velocity, respectively); however, echocardiogram and MUGA scan findings were not significantly associated with HIC or T2*-MRI. CONCLUSIONS: Diastolic dysfunction is not associated with transfusional iron burden or myocardial iron deposition among children with SCA. Diastolic dysfunction likely results from disease pathophysiology and severity rather than iron overload.