Key result
Myocardial extracellular volume was significantly higher in thalassemia major patients with prior myocardial iron overload compared to those without iron overload (31.3% vs 28.2%, P=0.030).
Why the study?
Does myocardial extracellular volume (ECV) measured by cardiac MRI correlate with myocardial iron overload in patients with thalassemia major?
Observational (n=40)
Does myocardial extracellular volume (ECV) measured by cardiac MRI correlate with myocardial iron overload in patients with thalassemia major?
Absolute Event Rate: 31.3% vs 28.2%
p-value: p=0.030
Myocardial extracellular volume is significantly increased in thalassemia major patients with prior myocardial iron overload, potentially reflecting diffuse interstitial myocardial fibrosis.
May indicate residual fibrosis after iron overload in thalassemia; hypothesis-generating for ECV monitoring, needing prospective validation.
Purpose To quantify myocardial extracellular volume (ECV) by using cardiac magnetic resonance (MR) imaging in thalassemia major and to investigate the relationship between ECV and myocardial iron overload. Materials and Methods With institutional review board approval and informed consent, 30 patients with thalassemia major (mean age ± standard deviation, 34.6 years ± 9.5) and 10 healthy control subjects (mean age, 31.5 years ± 4.4) were prospectively recruited (clinicaltrials.gov identification number NCT02090699). Nineteen patients (63.3%) had prior myocardial iron overload (defined as midseptal T2* < 20 msec on any prior cardiac MR images). Cardiac MR imaging at 1.5 T included cine steady-state free precession for ventricular function, T2* for myocardial iron quantification, and unenhanced and contrast material-enhanced T1 mapping. ECV was calculated with input of the patient's hematocrit level. Peak systolic global longitudinal strain by means of speckle tracking was assessed with same-day transthoracic echocardiography. Statistical analysis included use of the two-sample t test, Fisher exact test, and Spearman correlation. Results Unenhanced T1 values were significantly lower in patients with prior myocardial iron overload than in control subjects (850.3 ± 115.1 vs 1006.3 ± 35.4, P < .001) and correlated strongly with T2* values (r = 0.874, P < .001). Patients with prior myocardial iron overload had higher ECV than did patients without iron overload (31.3% ± 2.8 vs 28.2% ± 3.4, P = .030) and healthy control subjects (27.0% ± 3.1, P = .003). There was no difference in ECV between patients without iron overload and control subjects (P = .647). ECV correlated with lowest historical T2* (r = -0.469, P = .010) but did not correlate significantly with left ventricular ejection fraction (r = -0.216, P = .252) or global longitudinal strain (r = -0.164, P = .423). Conclusion ECV is significantly increased in thalassemia major and is associated with myocardial iron overload. These abnormalities may potentially reflect diffuse interstitial myocardial fibrosis. (©) RSNA, 2015 Online supplemental material is available for this article.
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Hanneman et al. (2015) conducted an observational in Thalassemia major (n=40). Cardiac MR imaging vs. Patients without iron overload and healthy controls was evaluated on Myocardial extracellular volume (ECV) (p=0.030). Myocardial extracellular volume was significantly higher in thalassemia major patients with prior myocardial iron overload compared to those without iron overload (31.3% vs 28.2%, P=0.030).
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