Normalized Left Ventricular Volumes and Function in Thalassemia Major Patients with Normal Myocardial Iron.
Authors: Westwood Mark A. , Anderson Lisa J. , Maceira Alicia M. , Prescott Emma , Porter John B. , Wonke Beatrix , Walker Malcolm J. , Pennell Dudley J. 
Published: October 2019

Repeated blood transfusions in Thalassemia Major (TM) may lead to myocardial iron accumulation and death. Left ventricular (LV) function is commonly used to assess for iron overload, however, the reference range in TM for these variables in the absence of myocardial iron loading is not known. We used cardiovascular magnetic resonance (CMR) in 205 TM patients and studied those (N=81) with normal myocardial T2* measurements (T2*>20ms) and by inference without excess myocardial iron. Resting LV volumes and function normalized to body surface area were compared with 40 age and gender matched healthy controls. All LV parameters were significantly different (p<0.05) in TM patients (see tables 1 and 2). The lower limit for ejection fraction was higher in TM (males 59 vs 55%, females 63 vs 59%, both P<0.001). The upper limit for end-diastolic volume index was higher in TM (males 152 vs 105 mL/m2, females 121 vs 99 mL/m2, both P<0.05). In TM the cardiac output index (P<0.001) was increased. In conclusion, at rest TM patients with normal myocardial T2* values and no excess myocardial iron loading have a hyperdynamic circulation and substantially different values for LV parameters compared with controls. Significant misdiagnosis of cardiomyopathy will result from comparison of TM patients with normal ranges.

LV Parameters Normalized to Body Surface Area in Males. TM Patients (Mean±SD) Controls (Mean±SD) LV parameters normalized to body surface area for males with mean and standard deviations divided into TM patients with no myocardial iron loading and non-anemic age matched controls. The ejection fraction is not indexed to body surface area as it does not vary significantly with body habitus. LVEDVI - left ventricular end-diastolic volume index, LVESVI - left ventricular end-systolic volume index, LVSVI - left ventricular stroke volume index, LVEF - left ventricular ejection fraction, LVMI - left ventricular mass index, CO - cardiac output, COI cardiac output index. LVEDVI (mL/m 2 ) 97.2±27.2 84.1±10.5 LVESVI (mL/m 2 ) 23.1±5.2 29.6±6.1 LVSVI (mL/m 2 ) 70.8±15.8 54.4±7.1 LVEF 71.0±6.1 64.9±5.0 LVMI (g/m 2 ) 84.6±20.3 75.0±8.4 CO (L/min) 9.8±3.2 6.8±1.5 COI (L/min/m 2 ) 5.7±1.9 3.5±0.7 LV Parameters Normailzed to Body Surface Area in Females TM Patients (Mean±SD) Controls (Mean±SD) LV parameters normalized to body surface area for females with mean and standard deviations divided into TM patients with no myocardial iron loading and non-anemic age matched controls. The ejection fraction is not indexed to body surface area as it does not vary significantly with body habitus. LVEDVI - left ventricular end-diastolic volume index, LVESVI - left ventricular end-systolic volume index, LVSVI - left ventricular stroke volume index, LVEF - left ventricular ejection fraction, LVMI - left ventricular mass index, CO - cardiac output, COI cardiac output index. LVEDVI (mL/m 2 ) 87.4±16.6 79.4±9.8 LVESVI (mL/m 2 ) 20.8±7.3 26.1±4.7 LVSVI (mL/m 2 ) 66.5±12.4 53.3±7.3 LVEF 75.1±5.9 67.1±4.3 LVMI (g/m 2 ) 69.9±17.3 61.9±7.9 CO (L/min) 8.2±2.0 5.8±1.6 COI (L/min/m 2 ) 5.2±1.3 3.4±0.8