RV volumetric and functional parameters have been difficult to measure using conventional imaging techniques due to the irregular geometry of the RV chamber, the size and quantity of the RV trabeculae, and the proximity of the RV to the chest wall which impairs echocardiographic assessment. CMR suffers less from these drawbacks because of its inherent 3D nature and high blood to myocardium contrast and is therefore considered to be the most accurate and reproducible technique for assessing RV volumes and EF [23, 24]. Attention to correct definition of the basal slice during acquisition and subsequent analysis is however pivotal. The improved confidence of measuring RV volumes and function from CMR and other techniques has assisted the understanding the importance of the RV in cardiac disease. RVEF is an important predictor of outcome in dilated cardiomyopathy, which is both independent of and incremental to LV EF . The predictive value of RV function has also been shown in congenital heart disease,[25–27] chronic systolic dysfunction, and ischemic heart failure,[16, 17, 29, 30] with RVEF being shown to be an independent predictor of outcome [16, 17]. Accordingly, the effects of myocardial iron loading on RV function may be important in thalassaemia patients.
In the current study, we found a significant improvement in RVEF (increase) and RVESV (reduction) with deferiprone therapy. These improvements parallel the previously reported LV response . There was no significant increase in RVEDV suggesting loading conditions did not play an important role. A flat RV response was seen in the deferoxamine group, which again mirrors LV behaviour. The between groups analysis showed superiority for deferiprone over deferoxamine for both the reduction in RVESV and the increase in RVEF. The magnitude of improvement in RVEF and reduction in RVESV were greater for patients with a higher ESV and lower EF at baseline. Interestingly neither LVEF nor RVEF improved significantly in the deferoxamine group despite the improvement in T2*. The cause for this difference in functional response is not fully understood, but the explanation may lie in the additional effects of deferiprone on restoring normal cardiac mitochondrial function, possibly through effects on reducing reactive oxygen species .
There is little other data relating RV function changes with the iron chelators, but a recently published abstract relating to a longitudinal trial of the efficacy of deferasirox in myocardial siderosis, showed a significant improvement in myocardial iron levels with an improvement in RVEF at 1 year, but no change in LV function at 1, 2, and 3  years of follow up. The significance of this discrepancy between RV and LV response to deferasirox is not currently clear, though it is possible that the RV response is an early signal of myocardial iron clearance as LV compliance and filling pressure improves.
Data acquisition for this study was originally designed to assess the change in T2* and LV functional parameters in response to therapy. Therefore no RV long axis images were obtained to construct 3-dimentional models for volumetric analysis, but the requirement for this was removed by using direct manual planimetry for quantitative analysis of RV volumes. Pulmonary arterial pressure was not systematically measured using echocardiography of the tricuspid regurgitant jet, but here was no CMR evidence of raised pulmonary artery pressure in our patients, and pulmonary hypertension is rare in well treated thalassaemia major . Direct RV measurement of T2* would have been interesting in this population to compare with changes in RV volumes and function, however, it is challenging to measure T2* in the thin wall of the RV and this was not attempted in the randomized controlled trial.