Performance and Correlations of Myocardial Contraction Fraction Derived From MRI in Transfusion-Dependent Thalassemia Patients.

Background: Myocardial contraction fraction (MCF) is a promising volumetric index of myocardial function.

Purpose: To evaluate the association of MRI-derived MCF with demographic characteristics, clinical data, MRI findings, and the history of heart failure in patients with transfusion-dependent thalassemia (TDT).

Study Type: Retrospective.

Subjects: 1154 TDT patients (52.9% female, 37.46 ± 10.67 years) enrolled in the Extension-Myocardial Iron Overload in Thalassemia project and 167 healthy subjects (54.5% female, 36.33 ± 15.78 years).

Field Strength/sequence: 1.5 T/cine imaging for assessment of left ventricular (LV) function parameters, gradient-echo T2* technique for myocardial iron overload (MIO) assessment, late gadolinium enhancement (LGE) imaging for detection of replacement myocardial fibrosis.

Assessment: MCF was calculated as LV stroke volume divided by LV myocardial volume.

Statistical Tests: Independent-samples t-test, Wilcoxon signed-rank test, and chi-squared test for comparison between groups; analysis of covariance; Pearson's or Spearman's correlations; univariable and stepwise multivariable linear regression analyses; receiver operating characteristic curve analysis for assessment of diagnostic efficiency and DeLong's test for area under the curves (AUCs) comparison. Statistical significance was defined as p < 0.05.

Results: Healthy subjects and TDT patients showed comparable MCF values (99.5% ± 15.0% vs. 102.7% ± 29.7%, p = 0.820). In TDT, MCF was significantly lower in males compared to females (98.4% ± 27.1% vs. 106.6% ± 31.3%) and in patients with diabetes (96.8% ± 29.7% vs. 103.7% ± 29.1%). MCF significantly decreased with age (R = -0.066). MCF was significantly correlated with global heart T2* values (R = 0.075), and patients with MIO (T2* < 20 ms) had a significantly lower MCF compared to those without (96.3% ± 22.0% vs. 103.3% ± 30.2%). MCF had a significant inverse correlation with the number of LGE-positive segments (R = -0.314). MCF demonstrated a diagnostic performance comparable to that of global heart T2* values in distinguishing between TDT patients with and without a history of heart failure (AUC 0.63 vs. 0.58, p = 0.401 for the difference). The LV ejection fraction did not significantly differentiate patients based on heart failure history (AUC = 0.55, p = 0.223).

Data Conclusion: In patients with TDT, MCF was significantly correlated with MIO and LGE extent. Additionally, patients with a history of heart failure had significantly impaired MCF.

Evidence Level: 4. TECHNICAL EFFICACY: Stage 2.