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Rapid Fire Abstracts

Rapid Fire 05- Miscellaneous II

Clinical correlates of left ventricular strain parameters by cardiac magnetic resonance in beta-thalassemia major patients (RF_FR_308)

Friday, January 31, 2025
9:20 AM – 9:30 AM East Coast USA Time
Location: Blue Room PreFunction
Background:

In β-thalassemia major (TM), early myocardial iron overload (MIO) is not detected by changes in left ventricular ejection fraction (LV EF). Myocardial strain analysis using CMR-feature tracking (FT) can assess subclinical myocardial dysfunction before LV EF impairment occurs.

We evaluated the cross-sectional relationship of the CMR-derived LV strain values with demographics, clinical data and CMR parameters among β-TM patients.

Methods:

We considered 266 β-TM patients (134 females, 37.08±11.60 years) consecutively enrolled in the Extension-Myocardial Iron Overload in Thalassemia (E-MIOT) project.
The CMR protocol included cine images for the assessment of global longitudinal strain (GLS), global circumferential strain (GCS), and global radial strain (GRS) using FT and for the quantification of LV function parameters, the T2* technique for the assessment of myocardial iron overload, and late gadolinium enhancement (LGE) technique.

Results:

Table 1 shows the demographic, clinical and CMR characteristics of TM patients and their association with LV strains.

All strain parameters exhibited a significant sex difference and correlated with body surface area, while they were independent from age, age at start of regular transfusion and chelation, presence of diabetes, and levels of pre-transfusion hemoglobin and ferritin. In the multivariable regression analysis, sex emerged as the only significant predictor of all strain measures.

All LV strains were significantly correlated with each other.

The LV GCS and GRS were not correlated to cardiac iron levels, while the GLS exhibited a significant association with global heart T2* values and number of segments with T2*< 20ms. The LV GLS was significantly lower in patients with significant MIO (global heart T2*< 20 ms) than in patients without MIO (Figure 1A). Analysis of the ROC curve (Figure 1B) showed an area under the curve of 0.63 (95%CI=0.57-0.69) with a best GLS cut-off of -12.76% for the detection of significant MIO (p=0.019).

All LV strains were significantly correlated with LV end-diastolic volume index, LV end-systolic volume index, LV mass index, and LV EF.

One-hundred and seventy-three (65.0%) patients received the contrast medium and LV LGE was detected in 70 (40.5%) of them. LV GCS and GLS were comparable between patients without and with LGE, while LGE was associated with significantly reduced LV GRS. In the subgroup of LGE-positive patients, the number of segments with LGE (mean: 2.74±1.94; range: 1-9) significantly correlated with all LV strains (GCS: R=0.411, p< 0.0001; GRS: R=-0.415, p< 0.0001; GLS: R=0.377, p< 0.0001).

Conclusion:

Among LV strain parameters, only GLS demonstrated a significant association with cardiac iron levels, likely due to an increased vulnerability of the subendocardial layers (represented by GLS) to ischemic, toxic, and metabolic factors. The number of segments involved by LV LGE seems to influence the contractility of all myocardial fibers, leading to LV deformation dysfunction.