ABSTRACT: BACKGROUND: It remains incompletely understood whether patients with transfusion related cardiac iron overload without signs of heart failure exhibit already subclinical alterations of systolic left ventricular (LV) dysfunction. Therefore we performed a comprehensive evaluation of systolic and diastolic cardiac function in such patients using tagged and phase-contrast CMR. METHODS: 19 patients requiring regular blood transfusions for chronic anemia and 8 healthy volunteers were investigated using cine, tagged, and phase-contrast and T2* CMR. LV ejection fraction, peak filling rate, end-systolic global midventricular systolic Eulerian radial thickening and shortening strains as well as left ventricular rotation and twist, mitral E and A wave velocity, and tissue e' wave and E/e' wave velocity ratio, as well as isovolumic relaxation time and E wave deceleration time were computed and compared to cardiac T2*. RESULTS: Patients without significant iron overload (T2*>20 ms, n=9) had similar parameters of systolic and diastolic function as normal controls, whereas patients with severe iron overload (T2*<10 ms, n=5), had significant reduction of LV ejection fraction (54+/-2% vs. 62+/-6% and 65+/-6% respectively p<0.05), of end-systolic radial thickening (+6+/-4% vs. +11+/-2 and +11+/-4% respectively p<0.05) and of rotational twist (1.6+/-0.2 degrees vs. 3.0+/-1.2 and 3.5+/-0.7 degrees respectively, p<0.05) than patients without iron overload (T2*>20 ms) or normal controls. Patients with moderate iron overload (T2* 10-20 ms, n=5), had preserved ejection fraction (59+/-6%, p=NS vs. pts. with T2*>20 ms and controls), but showed reduced maximal LV rotational twist (1.8+/-0.4 degrees). The magnitude of reduction of LV twist (r=0.64, p<0.001), of LV ejection fraction (r=0.44, p<0.001), of peak radial thickening (r=0.58, p<0.001) and of systolic (r=0.50, p<0.05) and diastolic twist and untwist rate (r=-0.53, p<0.001) in patients were directly correlated to the logarithm of cardiac ...