Farrukh Shah

Normalized left ventricular volumes and function in thalassemia major patients with normal myocardial iron

To determine the reference range in thalassemia major (TM) for left ventricular (LV) function.

Noncontrast myocardial T1 mapping using cardiovascular magnetic resonance for iron overload

To explore the use and reproducibility of magnetic resonance‐derived myocardial T1 mapping in patients with iron overload.

Myocardial tissue characterization and the role of chronic anemia in sickle cell cardiomyopathy

To use cardiovascular magnetic resonance (CMR) techniques to examine possible causes for the left ventricular (LV) dilatation that occurs in sickle cell disease (SCD), including the effects of chronic anemia, iron‐induced cardiomyopathy, and regional fibrosis due to sludge infarcts that occur during sickle crises.

Recent Insights into Interactions of Deferoxamine with Cellular and Plasma Iron Pools: Implications for Clinical Use

Abstract: Despite the availability of deferoxamine (DFO) for more than three decades, its rates of interaction with cellular iron pools in different tissues, and the effects of its pharmacokinetics on the interaction with plasma iron pools, remain incompletely understood. The positive charge of DFO, together with the negative resting potential in vertebrate cells, favors cellular uptake, whereas the low lipophilicity and high molecular weight counter this effect. The findings presented suggest a facilitated uptake of DFO into hepatocytes, being several hundred‐fold faster than into red cells. Antibodies that selectively recognize ferrioxamine (FO) show that initial hepatocellular iron chelation is cytosolic, but later transposes to lysosomal and ultimately canalicular compartments. Strong FO staining is visible in myocytes within 4‐8 h after commencing a subcutaneous DFO infusion, indicating effective chelation of myocyte iron. A methodology was developed to study the interaction of DFO and its metabolites with plasma iron pools by stabilizing DFO with aluminum ions, thereby preventing iron shuttling from non‐transferrin‐bound iron (NTBI) onto DFO after plasma collection. DFO removes only about a third of NTBI rapidly, and NTBI is rarely cleared completely. Increasing DFO dosing does not increase NTBI removal, but instead leads to a greater rebound in NTBI on cessation of intravenous infusion. Thus, intermittent infusions of high‐dose DFO are less desirable than continuous infusions at low doses, particularly in high‐risk patients. Here the benefits of continuous DFO on heart function occur before changes in T2*‐visible storage iron, consistent with early removal of a toxic labile iron pool within myocytes.

A phase 2 study of the safety, tolerability and pharmacodynamics of FBS0701, a novel oral iron chelator, in transfusional iron overload

This was a 24-week, multicenter phase-2 study designed to assess safety, tolerability, and pharmacodynamics of FBS0701, a novel oral chelator, in adults with transfusional iron overload. Fifty-one patients, stratified by transfusional iron intake, were randomized to FBS0701 at either 14.5 or 29 mg/kg/d (16 and 32 mg/kg/d salt form). FBS0701 was generally well tolerated at both doses. Forty-nine patients (96%) completed the study. There were no drug-related serious adverse events. No adverse events (AEs) showed dose-dependency in frequency or severity. Treatment-related nausea, vomiting, abdominal pain, and diarrhea were each noted in < 5% of patients. Mean serum creatinine did not change significantly from Baseline or between dose groups. Transaminases wer increased in 8 (16%), three of whom acquired HCV on-study from a single blood bank while five had an abnormal baseline ALT. The 24 week mean change in liver iron concentration (ΔLIC) at 14.5 mg/kg/d was +3.1 mg/g (dw); 29% achieved a decrease in LIC. Mean ΔLIC at 29 mg/kg/d was -0.3 mg/g (dw); 44% achieved a decrease in LIC (P < .03 for ΔLIC between doses). The safety and tolerability profile at therapeutic doses compare favorably to other oral chelators.

Iron Overload in Thalassemia and Related Conditions: Therapeutic Goals and Assessment of Response to Chelation Therapies

Transfusional iron loading inevitably results in hepatic iron accumulation, with variable extrahepatic distribution that is typically less pronounced in sickle cell disease than in thalassemia disorders. Iron chelation therapy has the goal of preventing iron-mediated tissue damage through controlling tissue iron levels, without incurring chelator-mediated toxicity. Historically, target levels for tissue iron control have been limited by the increased frequency of deferoxamine-mediated toxicity and low levels of iron loading. With newer chelation regimes, these limitations are less evident. The reporting of responses to chelation therapies has typically focused on average changes in serum ferritin in patient populations. This approach has three limitations. First, changes in serum ferritin may not reflect trends in iron balance equally in all patients or for all chelation regimens. Second, this provides no information about the proportion of patients likely respond. Third, this gives insufficient information about iron trends in tissues such as the heart. Monitoring of iron overload has advanced with the increasing use of MRI techniques to estimate iron balance (changes in liver iron concentration) and extrahepatic iron distribution (myocardial T2*). The term nonresponder has been increasingly used to describe individuals who fail to show a downward trend in one or more of these variables. Lack of a response of an individual may result from inadequate dosing, high transfusion requirement, poor treatment adherence, or unfavorable pharmacology of the chelation regime. This article scrutinizes evidence for response rates to deferoxamine, deferiprone (and combinations), and deferasirox.

On myocardial siderosis and left ventricular dysfunction in hemochromatosis

BackgroundChronically increased intestinal iron uptake in genetic hemochromatosis (HC) may cause organ failure. Whilst iron loading from blood transfusions may cause dilated cardiomyopathy in conditions such as thalassemia, the in-vivo prevalence of myocardial siderosis in HC is unclear, and its relation to left ventricular (LV) dysfunction is controversial. Most previous data on myocardial siderosis in HC has come from post-mortem studies.MethodsCardiovascular magnetic resonance (CMR) was performed at first presentation of 41 HC patients (58.9 ±14.1 years) to measure myocardial iron and left ventricular (LV) ejection fraction (EF).ResultsIn 31 patients (genetically confirmed HFE-HC), the HFE genotype was C282Y/C282Y (n = 30) and C282Y/H63D (n = 1). Patients with other genotypes (n = 10) were labeled genetically unconfirmed HC. Of the genetically confirmed HFE-HC patients, 6 (19%) had myocardial siderosis (T2* <20 ms). Of these, 5 (83%) had heart failure and reduced LVEF which was correlated to the severity of siderosis (R2 0.57, p = 0.049). Two patients had follow-up scans and both had marked improvements in T2* and LVEF following venesection. Myocardial siderosis was present in 6/18 (33%) of patients with presenting ferritin ≥1000 μg/L at diagnosis but in 0/13 (0%) patients with ferritin <1000 μg/L (p = 0.028). Overall however, the relation between myocardial siderosis and ferritin was weak (R2 0.20, p = 0.011). In the 10 genetically unconfirmed HC patients, 1 patient had mild myocardial siderosis but normal EF. Of all 31 patients, 4 had low LVEF from other identifiable causes without myocardial siderosis.ConclusionMyocardial siderosis was present in 33% of newly presenting genetically confirmed HFE-HC patients with ferritin >1000 μg/L, and was the commonest cause of reduced LVEF. Heart failure due to myocardial siderosis was only found in these HFE-HC patients, and was reversible with venesection. Myocardial iron was normal in patients with other causes of LV dysfunction.

Right ventricular volumes and function in thalassemia major patients in the absence of myocardial iron overload

AimWe aimed to define reference ranges for right ventricular (RV) volumes, ejection fraction (EF) in thalassemia major patients (TM) without myocardial iron overload.Methods and resultsRV volumes, EF and mass were measured in 80 TM patients who had no myocardial iron overload (myocardial T2* > 20 ms by cardiovascular magnetic resonance). All patients were receiving deferoxamine chelation and none had evidence of pulmonary hypertension or other cardiovascular comorbidity. Forty age and sex matched healthy non-anemic volunteers acted as controls. The mean RV EF was higher in TM patients than controls (males 66.2 ± 4.1% vs 61.6 ± 6%, p = 0.0009; females 66.3 ± 5.1% vs 62.6 ± 6.4%, p = 0.017), which yielded a raised lower threshold of normality for RV EF in TM patients (males 58.0% vs 50.0% and females 56.4% vs 50.1%). RV end-diastolic volume index was higher in male TM patients (mean 98.1 ± 17.3 mL vs 88.4 ± 11.2 mL/m2, p = 0.027), with a higher upper limit (132 vs 110 mL/m2) but this difference was of borderline significance for females (mean 86.5 ± 13.6 mL vs 80.3 ± 12.8 mL/m2, p = 0.09, with upper limit of 113 vs 105 mL/m2). The cardiac index was raised in TM patients (males 4.8 ± 1.0 L/min vs 3.4 ± 0.7 L/min, p < 0.0001; females 4.5 ± 0.8 L/min vs 3.2 ± 0.8 L/min, p < 0.0001). No differences in RV mass index were identified.ConclusionThe normal ranges for functional RV parameters in TM patients with no evidence of myocardial iron overload differ from healthy non-anemic controls. The new reference RV ranges are important for determining the functional effects of myocardial iron overload in TM patients.

Prospective study of histomorphometry, biochemical bone markers and bone densitometric response to pamidronate in β-thalassaemia presenting with osteopenia-osteoporosis syndrome

This study aimed to evaluate bone remodelling disorders in thalassaemia by using pamidronate (PD) infusion with or without hormone replacement therapy (HRT) as a diagnostic‐therapeutic tool. In this prospective study, 24 adult thalassaemia major (TM) and 10 thalassaemia intermedia (TI) patients received either PD and HRT or HRT only (controls) for 3 years. Eugonadal patients with TI had PD only. Bone remodelling was assessed by dual energy X ray absorptiometry (DXA scan), type 1‐collagen biochemical bone markers (BBM) and histomorphometry of iliac crest biopsy before and after PD. As a group, thalassaemics had a significant improvement in spinal and femoral bone mineral density Z scores following PD (P < 0·01) compared to the controls. Although BBM were comparable pre‐therapy, they were significantly lower in the PD cohort (P < 0·001) compared to the control group. All patients had osteopenia, diminished osteoid formation and bone volume on histomorphometry pre‐therapy with high turnover bone disease (HTO) in TM and low‐turnover disease (LTO) in TI. In TM, bone volume improved significantly, whereas TI patients showed little or no response to PD. In conclusion, histomorphometry data suggest that TM patients have a distinct pathology of high turnover bone disease compared to TI patients, who have low‐turnover disease.

Prevalence of Low Bone Mass and Vitamin D Deficiency in β-Thalassemia Major

Abstract Low bone mass, a major cause of morbidity in patients with β-thalassemia major (β-TM), is multifactorial. There is lack of data about the current prevalence of low bone mass in patients with β-TM. The aims of this study are to examine the current prevalence of low bone mass in β-TM patients and the association between demographic characteristics, markers of iron overload, endocrinopathies, glycemic status and bone mineral density (BMD) as well as to study the 25-OH-vitamin D status of the patients and its relationship with BMD. Our institution serves the largest cohort of β-TM patients in the UK. From 99 patients (49 males, 50 females) with a mean ± standard deviation (SD) age of 36 ± 9 years, 55.5% had low BMD for their age as defined by Z-score BMD <−2.0 either at the lumbar spine (43.9%) or at the hip (25.5%). The only statistically significant association on the multivariate analysis was between hypogonadism and low BMD at the lumbar spine. In our study, 29.9% of patients had vitamin D deficiency, 65.7% had vitamin D insufficiency and 12.4% had optimal levels. No association between vitamin D status and low bone mass was found. Our study demonstrated a much lower prevalence of low bone mass in adults with β-TM compared to previous studies. Further studies are needed to examine whether this suggests a widespread improvement across patients with β-TM possibly due to advances in therapeutics. Most patients had suboptimal 25-OH-vitamin D levels, but no association between vitamin D status and bone mass was demonstrated.