After R2* CMR was completed, each short axis slice was cut into 6 sectors of 60° each, and then each sector was subdivided into 3 transmural layers (18 LV samples, figure 1e). For each short axis slice, 2 samples were also taken from the RV free wall (20 myocardial samples per slice). Additional samples were taken from the right (3) and left (3) atrium, the inter-atrial septum (1) and each of the valves (4). For the LV myocardial R2* calibration analysis, all LV samples were directly compared with the CMR R2* scan. For the segmental analysis of the distribution of myocardial iron, we used the American Heart Association/American College of Cardiology (AHA/ACC) 16-segment model.20 (link) Three myocardial slices from each heart were used for this analysis: the mid-ventricular, apical and basal slices, as per the model. Each segment comprised the full transmural extent of myocardium. To match the apical slice to 4 segments as dictated in the 16 segment model, the 2 apical-septal sectors were analyzed together, and the 2 apical-lateral sectors were analyzed together. The wet weight of each piece of tissue was recorded after discarding excess formalin. Samples were then freeze-dried and the dry weight (dw) was recorded immediately after removal from the lyophilizer. Following acid digestion, iron measurement was performed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). The iron concentrations in samples of NIST human liver standard 4352 were used as quality controls for ICP-AES analysis.