Abstract 2121: Myocardial T2* Effects 3D MRI Myocardial Strain in Patients with Transfusion-Induced Haemochromatosis
Background: Early detection of transfusion-induced myocardial iron loading and its intervention with aggressive chelation therapy may delay or reverse heart failure. Myocardial T2* relaxometry has been proposed as a sensitive measure of myocardial iron accumulation. We hypothesise that low myocardial T2*, indicating high myocardial iron, is associated with reduced 3D MRI myocardial strain.
Methods: Myocardial T2*, R2-MRI liver iron quantification, short and long axis 7mm grid tagged SPAMM cine imaging were acquired on a Siemens Sonata 1.5T MRI scanner in 24 patients (10M, age 32±7) with congenital haemoglobinopathy (22 thalassemia major, 1 thalassemia intermedia, 1 Diamon-Blackfan anemia). T2* intraobserver variability (55 scans), interobserver variability (24 patients) and interscan variability (12 patients) with scans repeated within 24 hours were assessed by % coefficient of variation (%CV) and Bland-Altman analysis. T2* cut-off at 10msec separated high and low myocardial iron groups. Peak 3D circumferential, longitudinal and shear systolic strains and diastolic strain relaxation rates were averaged over all regions as a measure of systolic and diastolic myocardial function. Serum ferritin in the preceding 12 months was recorded.
Results: Myocardial T2* intraobserver, interobserver and interscan %CV were 6.2%, 8.1% and 5% respectively. Mean difference between values (95% limits of agreement) were intraobserver 0.3msec (−5.0, 5.7 msec), interobserver 0.5msec (−3.6, 4.7 msec), and interscan 0.1 msec (−4.0, 4.3 msec). High myocardial iron (n=15) had a lower EF (47.4% vs 56.6%, P=0.002) and peak 3D systolic strain (circumferential: 16.3% vs 18.6%, longitudinal: 13.5% vs 15.4%, shear: 4.1% vs 6.0%, all P=0.05) than low myocardial iron (n=9). Only peak diastolic shear strain rate was reduced in high myocardial iron (−24%/sec vs −35%/sec, P=0.02). Liver iron and serum ferritin were not different between myocardial iron groups.
Conclusions: Myocardial T2* performed at our institution was reproducible. High myocardial iron, indicated by low myocardial T2*, was associated with lower LVEF, lower peak 3D systolic strain consistent with systolic impairment and only diastolic shear strain suggesting a lesser degree of diastolic dysfunction.