Beatrix Wonke

Comparison of effects of oral deferiprone and subcutaneous desferrioxamine on myocardial iron concentrations and ventricular function in beta-thalassaemia

BACKGROUND Despite the introduction of the parenteral iron chelator desferrioxamine more than 30 years ago, 50% of patients with thalassaemia major die before the age of 35 years, predominantly from iron-induced heart failure. The only alternative treatment is oral deferiprone, but its long-term efficacy on myocardial iron concentrations is unknown. METHODS We compared myocardial iron content and cardiac function in 15 patients receiving long-term deferiprone treatment with 30 matched thalassaemia major controls who were on long-term treatment with desferrioxamine. Myocardial iron concentrations were measured by a new magnetic-resonance T2* technique, which shows values inversely related to tissue iron concentration. FINDINGS The deferiprone group had significantly less myocardial iron (median 34.0 ms vs 11.4 ms, p=0.02) and higher ejection fractions (mean 70% [SD 6.5] vs 63% [6.9], p=0.004) than the desferrioxamine controls. Excess myocardial iron (T2* <20 ms) was less common in the deferiprone group than in the desferrioxamine controls (four [27%] vs 20 [67%], p=0.025), as was severe (T2* <10 ms) iron overload (one [7%] vs 11 [37%], p=0.04). The odds ratio for excess myocardial iron in the desferrioxamine controls versus the deferiprone group was 5.5 (95% CI 1.2-28.8). INTERPRETATION Conventional chelation treatment with subcutaneous desferrioxamine does not prevent excess cardiac iron deposition in two-thirds of patients with thalassaemia major, placing them at risk of heart failure and its complications. Oral deferiprone is more effective than desferrioxamine in removal of myocardial iron.

Myocardial iron clearance during reversal of siderotic cardiomyopathy with intravenous desferrioxamine: a prospective study using T2* cardiovascular magnetic resonance.

Heart failure from iron overload causes 71% of deaths in thalassaemia major, yet reversal of siderotic cardiomyopathy has been reported. In order to determine the changes in myocardial iron during treatment, we prospectively followed thalassaemia patients commencing intravenous desferrioxamine for iron‐induced cardiomyopathy during a 12‐month period. Cardiovascular magnetic resonance assessments were performed at baseline, 3, 6 and 12 months of treatment, and included left ventricular (LV) function and myocardial and liver T2*, which is inversely related to iron concentration. One patient died. The six survivors showed progressive improvements in myocardial T2* (5·1 ± 1·9 to 8·1 ± 2·8 ms, P = 0·003), liver iron (9·6 ± 4·3 to 2·1 ± 1·5 mg/g, P = 0·001), LV ejection fraction (52 ± 7·1% to 63 ± 6·4%, P = 0·03), LV volumes (end diastolic volume index 115 ± 17 to 96 ± 3 ml, P = 0·03; end systolic volume index 55 ± 16 to 36 ± 6 ml, P = 0·01) and LV mass index (106 ± 14 to 95 ± 13, P = 0·01). Iron cleared more slowly from myocardium than liver (5·0 ± 3·3% vs. 39 ± 23% per month, P = 0·02). These prospective data confirm that siderotic heart failure is often reversible with intravenous iron chelation with desferrioxamine. Myocardial T2* improves in concert with LV volumes and function during recovery, but iron clearance from the heart is considerably slower than from the liver.

A Single Breath-Hold Multiecho T2* Cardiovascular Magnetic Resonance Technique for Diagnosis of Myocardial Iron Overload

To assess tissue iron concentrations by the use of a gradient echo T2* multiecho technique.

Combined therapy with deferiprone and desferrioxamine

In a proportion of transfusion‐dependent patients iron chelation with daily doses of deferiprone of 75 mg/kg body weight (b.w.) is inadequate. The effects on iron status of increasing the daily oral dose of deferiprone and/or combining deferiprone therapy with subcutaneous infusions of desferrioxamine have been studied in 13 transfusion‐dependent patients. Raising the daily dose of deferiprone in nine patients from 75 mg/kg to 83–100 mg/kg resulted in a fall in serum ferritin in all nine patients (t test for paired samples, P = 0.0022). Combined therapy of daily deferiprone with subcutaneous desferrioxamine on 2–6 d each week in five patients (with an increased dose of deferiprone in three patients) resulted in a fall in serum ferritin in all five patients studied after 7–15 months (P = 0.0791). No toxic side‐effects attributable to either drug occurred in these five patients or in the nine patients in whom the dose of deferiprone was increased. The effects of the drugs given on the same day on urine iron excretion were additive. These results suggest that increasing the dose of deferiprone or combining subcutaneous desferrioxamine with deferiprone therapy are two methods by which efficacy of iron chelation with deferiprone can be improved in patients inadequately chelated by a daily dose of deferiprone of 75 mg/kg b.w. More extensive trials including full metabolic balance studies are needed to establish the safety and efficacy of long‐term combined therapy.

Hepatic iron concentration combined with long-term monitoring of serum ferritin to predict complications of iron overload in thalassaemia major.

Clinical complications of transfusional iron overload are still common in patients with thalassaemia major (TM) and it is not clear how best to monitor body iron stores during long‐term follow‐up to anticipate tissue damage. In this study, we have reviewed a group of 32 patients who underwent liver biopsy between 1984 and 1986. We developed a method of assessing the trend in serum ferritin (TSF) during long‐term monitoring and compared this with mean serum ferritin (MSF) and initial liver iron (LI) concentration to determine whether, individually or in combination, they were accurate in predicting clinical outcome. LI levels were low (< 7 mg/g), medium (7–15 mg/g) and high (> 15 mg/g dry weight) in 15, 7 and 10 patients respectively. MSF was low (< 1500 μg/l), medium (1500–2500 μg/l) and high (> 2500 μg/l) in 10, 14 and 8 patients. TSF was low, medium and high risk in 9, 9 and 11 out of 29 evaluable patients. During a median follow‐up of 13·6 years (range 2·3–14·8 years) after biopsy, nine patients died and an additional three patients developed heart failure. Hypothyroidism developed in five, hypoparathyroidism in four, and diabetes mellitus in seven patients. Cirrhosis developed in four of 10 evaluable patients. The clinical end‐point of death or cardiac failure was significantly associated with increasing iron load using all three means of assessment. Although numbers were insufficient for statistical analysis, MSF or TSF were more closely associated with complications of iron overload than LI. There was no clear additional value in combining LI with MSF or TSF. The data show that quantitation of liver iron from a single liver biopsy has little value in long‐term monitoring of iron stores. Most complications can be avoided if ferritin levels can be brought down to <1500 μg/l.

Results of long-term deferiprone (L1) therapy: a report by the International Study Group on Oral Iron Chelators.

Summary This report updates the combined experience of four centres involved in the long‐term treatment of transfusional iron overload in 84 patients with the oral iron chelator deferiprone (L1) over 167 patient‐years. The source of L1 was variable, including two university research laboratories and three pharmaceutical firms. Compliance was rated as excellent in 48%, intermediate in 36%, and poor in 16% of patients. On a mean L1 dose of 73–81 mg/kg/d, urinary iron excretion was stable, at around 0 5 mg/kg/d, with no indication of a diminishing response with time. Serum ferritin showed a very steady decrease with time from an initial mean ±1SD of 4207 ±3118 to 1779 ± 1154μg/1 after 48 months (P< 0–001). 17 patients abandoned L1 therapy, Major complications of L1 requiring permanent discontinuation of treatment included agranulocytosis (three), severe nausea (four), arthritis (two) and persistent liver dysfunction (one). The remaining patients abandoned treatment because of low compliance (three) and conditions unrelated to L1 toxicity (four). Lesser complications permitting continued L1 treatment included transient mild neutropenia (four), zinc deficiency (12), transient increase in liver enzymes (37), moderate nausea (three) and arthropathy (17). There was no treatment‐related mortality. Although the complications associated with L1 treatment are significant and require close monitoring, they do not preclude effective long‐term therapy in the vast majority of patients. Further well‐controlled prospective studies of L1 are required in order to enable proper judgement of its suitability for general long‐term clinical use.

High prevalence of low bone mass in thalassaemia major

Cooleys original description of β‐thalassaemia major included marked bone deformities as a characteristic feature. These were thought to be due to expansion of haemopoiesis attempting to compensate for the congenital anaemia. Regular blood transfusions from infancy prevents these skeletal problems. Nevertheless, symptoms due to bone disease frequently occur in adult patients. Osteoporosis has not previously been reported as a cause of severe morbidity in thalassaemia major. The present study shows a high prevalence of low bone mass among thalassaemia major patients and analyses the predisposing causes. Bone density scans were performed in 82 patients with transfusion‐dependent β thalassaemia. Factors known to be associated with low bone mass such as gender, endocrine disorders and lifestyle activities, together with factors specific to the thalassaemia and its management, were included in a series of univariate analyses to ascertain any significant associations. 42 (51%) of the patients had severely low bone mass and a further 37 (45%) had low bone mass. The three factors showing a statistically significant association with severely low bone mass were male sex, 24/38 (63%) males had severely low bone mass, compared with 18/44 (41%) females, the lack of spontaneous puberty, 22/32 (69%) who required therapeutic induction of pubertal development had severely low bone mass, compared with 19/47 (40%) with spontaneous puberty and diabetes, 8/10 (80%) diabetic patients had severely low bone mass, compared with 23/56 (41%) with normal glucose tolerance. There was no association between the bone mineral density measurements and the haematological characteristics or treatment details of these patients. Severely low and low bone mass are common findings in patients with β‐thalassaemia major despite optimal transfusion and iron chelation. The associated features suggest that the severely low bone mass is due to endocrine abnormalities, in contrast to the haematological causes of bone disease characteristically seen in untreated thalassaemics.

Interscanner reproducibility of cardiovascular magnetic resonance T2* measurements of tissue iron in thalassemia

To assess interscanner reproducibility of tissue iron measurements in patients with thalassemia using gradient echo T2* measurements on two different MRI scanners.

High incidence of cardiomyopathy in beta-thalassaemia patients receiving regular transfusion and iron chelation : reversal by intensified chelation

Cardiac scintigraphy has been performed in 60 beta-thalassaemia major patients aged 8-35 years who received regular blood transfusions and subcutaneous desferrioxamine (DFX) chelation. Fifty-seven showed no clinical, radiological or electrocardiographic evidence of heart disease and 3 had clinically apparent cardiac failure. Twenty-two patients (37%) showed severe cardiac functional impairment defined by a resting left ventricular ejection fraction (LVEF) less than 45% and/or a drop of greater than 12% on stress, while 19 were normal and 19 had a mild abnormality. There was no significant correlation between abnormality of LVEF and age, serum ferritin, number of units transfused, dose and duration of subcutaneous DFX therapy, liver disease or sexual maturation. Non-compliant patients (defined as the use of subcutaneous DFX less than 4 times weekly) generally showed worse cardiac function. Repeat study on 17 patients after 6-28 months of better compliance with subcutaneous or intravenous DFX (using an indwelling catheter) showed a significant overall improvement in LVEF associated with a significant drop in serum ferritin. We conclude that cardiac scintigraphy uncovers a high incidence of cardiac functional abnormality in asymptomatic, well-transfused thalassaemia patients, particularly those poorly compliant with chelation. Those with poor LVEF results should be offered intensive chelation therapy to improve cardiac function.

Myocardial iron loading by magnetic resonance imaging T2* in good prognostic myelodysplastic syndrome patients on long‐term blood transfusions

Magnetic resonance imaging (MRI) was used to quantify myocardial iron loading by T2* in 11 transfusion‐dependent good prognostic myelodysplastic syndrome (MDS) patients. Myocardial T2*, left ventricular function and hepatic T2* were measured simultaneously. Patients had been on transfusion therapy for 13–123 months and had serum ferritin levels of 1109–6148 μg/l at the time of study. Five patients had not commenced iron chelation and had been transfused with a median of 63 red cell units and had a median serum ferritin level of 1490 μg/l. Six patients were on iron chelation and had been transfused with a median of 112 red cell units and had a median serum ferritin level of 4809 μg/l. Hepatic iron overload was mild in two, moderate in seven and severe in two patients. The median liver iron concentration was 5·9 mg/g dry weight in chelated patients and 9·5 mg/g in non‐chelated patients (P = 0·17; not significant). Myocardial T2* indicated absent iron loading in 10/11 patients (91%; 95% confidence interval 62–98%) and borderline‐normal in one patient. Left ventricular function was normal in all patients. No correlation was observed between increasing serum ferritin levels, hepatic iron overload and myocardial T2*. A long latent period relative to hepatic iron loading appears to predate the development of myocardial iron loading in transfusion‐dependent MDS patients.