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Beatrix Wonke

Publications and source records attributed to Beatrix Wonke.

9 recordsLinked to original sources
PubMed2006

Development of thalassaemic iron overload cardiomyopathy despite low liver iron levels and meticulous compliance to desferrioxamine.

It is believed that myocardial iron deposition and the resultant cardiomyopathy only occur in the presence of severe liver iron overload. Using cardiovascular magnetic resonance, it is now possible to assess myocardial and liver iron levels as well as cardiac function in the same scan, allowing this supposition to be examined. We describe a patient with progressive myocardial iron deposition and the development of early iron overload cardiomyopathy despite excellent compliance to standard subcutaneous desferrioxamine, minimal liver iron and well-controlled serum ferritin levels. These indirect markers remained far below the thresholds conventionally believed to be associated with increased cardiac risk.

Cardiomyopathies↗
PubMed2005

Randomized controlled trial of deferiprone or deferoxamine in beta-thalassemia major patients with asymptomatic myocardial siderosis.

Most deaths in beta-thalassemia major result from cardiac complications due to iron overload. Differential effects on myocardial siderosis may exist between different chelators. A randomized controlled trial was performed in 61 patients previously maintained on subcutaneous deferoxamine. The primary end point was the change in myocardial siderosis (myocardial T2(*)) over 1 year in patients maintained on subcutaneous deferoxamine or those switched to oral deferiprone monotherapy. The dose of deferiprone was 92 mg/kg/d and deferoxamine was 43 mg/kg for 5.7 d/wk. Compliance was 94% +/- 5.3% and 93% +/- 9.7% (P = .81), respectively. The improvement in myocardial T2(*) was significantly greater for deferiprone than deferoxamine (27% vs 13%; P = .023). Left ventricular ejection fraction increased significantly more in the deferiprone-treated group (3.1% vs 0.3% absolute units; P = .003). The changes in liver iron level (-0.93 mg/g dry weight vs -1.54 mg/g dry weight; P = .40) and serum ferritin level (-181 microg/L vs -466 microg/L; P = .16), respectively, were not significantly different between groups. The most frequent adverse events were transient gastrointestinal symptoms for deferiprone-treated patients and local reactions at the infusion site for deferoxamine. There were no episodes of agranulocytosis. Deferiprone monotherapy was significantly more effective than deferoxamine over 1 year in improving asymptomatic myocardial siderosis in beta-thalassemia major.

Adult↗
PubMed2005

Left ventricular diastolic function compared with T2* cardiovascular magnetic resonance for early detection of myocardial iron overload in thalassemia major.

PURPOSE: To compare left ventricular (LV) diastolic function with myocardial iron levels in beta thalassemia major (TM) patients, using cardiovascular magnetic resonance (CMR). MATERIALS AND METHODS: We studied 67 regularly transfused patients with TM and 22 controls matched for age, gender, and body surface area. The early peak filling rate (EPFR) and atrial peak filling rate (APFR) were determined from high-temporal-resolution ventricular volume-time curves. Myocardial iron estimation was achieved using myocardial T2* measurements. RESULTS: Myocardial iron loading was found in 46 TM patients (69%), in whom the EPFR correlated poorly with T2* (r = -0.20, P = 0.19). The APFR (r = 0.49, P < 0.001) and EPFR/APFR ratio (r = -0.62, P < 0.001) correlated better with T2*. The sensitivity of the diastolic parameters for detecting myocardial iron loading ranged from 4% (EPFR and APFR) to 17% (EPFR/APFR ratio). CONCLUSION: Myocardial iron overload results in diastolic myocardial dysfunction, but low sensitivity limits the use of a single estimation for early detection of iron overload, for which T2* has a superior categorical limit of normality.

Adult↗
PubMed2004

No difference in pubertal growth and final height between treated hypogonadal and non-hypogonadal thalassemic patients.

BACKGROUND: Many factors can negatively affect growth in thalassemic patients, and hypogonadism has been considered as the main factor responsible for their pubertal growth failure. OBJECTIVE: To evaluate the influence of hypogonadism and its treatment on pubertal growth and final height in thalassemic patients. METHODS: We compared the growth of 28 hypogonadal thalassemic patients in whom puberty was induced to that of 25 patients in whom puberty occurred spontaneously. RESULTS: In both groups of patients we observed reduced peak height velocity (induced puberty: females 4.9 +/- 2.1, males 6.0 +/- 1.8 cm/year; spontaneous puberty: females 6.1 +/- 1.5, males 7.3 +/- 2.1 cm/year) and pubertal height gain (induced puberty: females 11.3 +/- 4.0, males 18.0 +/- 4.5 cm/year; spontaneous puberty: females 15.8 +/- 2.7, males 18.1 +/- 5.3 cm/year) and a short final height (induced puberty: females -1.8 +/- 0.7, males -2.1 +/- 1.0 SDS; spontaneous puberty: females -2.3 +/- 1.0, males -1.9 +/- 1.0 SDS). CONCLUSIONS: Poor pubertal growth is present in thalassemic patients regardless of hypogonadism. Other factors are responsible for the reduced growth spurt and the final short stature observed in these patients.

Adolescent↗
PubMed2004

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.

Adult↗
PubMed2003

A single breath-hold multiecho T2* cardiovascular magnetic resonance technique for diagnosis of myocardial iron overload.

PURPOSE: To assess tissue iron concentrations by the use of a gradient echo T2* multiecho technique. MATERIALS AND METHODS: We compared the results of measurements of heart T2* from 32 patients using the established multiple breath-hold variable TR technique with a new multiecho sequence that acquires all images within a single breath-hold with constant TR. RESULTS: There was good agreement of myocardial T2* values between both methods in the abnormal range of T2* < 20 msec (mean difference 0.2 msec, 95% CI -1.3 to 0.9 msec, r = 0.97, P < 0.0001). The coefficient of variability between the methods was 3.5%. The interstudy reproducibility using the multiecho sequence had a variability coefficient of 2.3% in the abnormal T2* range and 5.8% over all T2* values. There was good agreement between the techniques for the liver T2* values. CONCLUSIONS: The use of the single breath-hold, multiecho acquisition allowed reliable quantification of myocardial T2*. The good reproducibility, speed, and T1 independence of this technique allows greater accuracy, faster patient throughput, and, therefore, reduced costs (which is important in developing countries where thalassemia is most prevalent).

Adolescent↗
PubMed2003

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

PURPOSE: To assess interscanner reproducibility of tissue iron measurements in patients with thalassemia using gradient echo T2* measurements on two different MRI scanners. MATERIALS AND METHODS: Twenty-five patients with thalassemia major had liver and myocardial T2* assessment using a Picker Edge 1.5T Scanner and a Siemens Sonata 1.5T scanner, with similar gradient echo sequences. In a subset of 13 patients, two scans on the Siemens scanner were performed to assess interstudy reproducibility. RESULTS: There was a highly significant, linear correlation between T2* values obtained for both the heart (r = 0.95) and the liver (r = 0.99) between scanners. The mean difference, coefficient of variability, and 95% confidence intervals between scanners were 0.8 msec, 9.4% and -5.0 to 6.7 msec for the heart; and 0.9 msec, 7.9% and -2.0 to 3.9 msec for the liver. The interstudy mean difference and coefficient of variability on the Siemens scanner was 0.3 msec and 4.8% (r = 0.99) for the heart, and 0.04 msec and 1.9% (r = 0.99) for the liver. CONCLUSION: The T2* technique for measuring tissue iron is reproducible between the two manufacturers' scanners. This suggests that the widespread implementation of the technique is possible for clinical assessment of myocardial iron loading in thalassemia.

Adult↗
PubMed2002

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.

Administration, Oral↗