Association between Diastolic Function Parameters and MRI T2 Measurements in a Sample of Iranian Patients with Major Thalassemia

Abstract

Background: The aim of the present study was to investigate the relationship between the echocardiographic indices of diastolic dysfunction and MRI T2 measurements, indicating myocardial iron loadings, in patients with thalassemia major and normal left ventricular ejection fractions. Methods: A series of consecutive patients with known thalassemia major under treatment with regular blood transfusions and iron chelation therapy were enrolled in the current study between July 2012 and June 2015 at Baharlou Hospital, Tehran, Iran. All the patients underwent cardiac MRI with the measurement of T2 for the liver and heart, echocardiographic examination with tissue Doppler assessment, and serum ferritin assay. The correlation between diastolic function parameters and T2 measurements was assessed using statistical software. Standard diastolic indices, comprising early (E) and late (A) transmitral peak flow velocities and early deceleration time (DT), were recorded. Results: The mean E/A, mean E/E′, and mean E′ were 2.09±0.54, 0.07±0.011, and 14±1.40 cm/s, respectively. The mean deceleration time (dt) was 190.97±35.89. The average serum ferritin level was 1498±783.08 ng/mL (range =212.7 to >3000 ng/mL). The mean cardiac T2 derived MRI was 26.58±7.54 ms. The frequencies of the different severities of myocardial iron loading based on myocardial T2 were as follows: 44 (80%) normal, 4 (7.3%) mild, 2 (3.6%) moderate, and 5 (9.1%) severe. MRI T2 did not have a significant correlation with E/A (r=0.091; P=0.508), E′ (r=0.130; P=0.345), E/E′ (r=0.005; P=0.971), and dt (r=0.028; P=0.838). Hepatic iron loading based on the MRI T2 values also did not have any correlation with the echocardiographic indices of left ventricular diastolic dysfunction—namely E/A (r=0.151; P=0.270), E′ (r=0.034; P=0.804), E/E′ (r=0.083; P=0.547), and dt (r=0.128; P=0.351). Conclusions: None of the echocardiographic diastolic function parameters examined in this study were found to be suitable for cardiac surveillance in transfusion-dependent patients affected by thalassemia major. Longitudinal studies are needed to evaluate the utility of echocardiographic and MRI parameters to predict cardiac events. At the moment, we cannot recommend the replacement of cardiac MR and T2 measurements, indicating myocardial iron loading, by Doppler echocardiography in patients with a normal systolic function. (Iranian Heart Journal 2016; 17(3):12-17)