Can myocardial remodeling be a useful surrogate predictor of myocardial iron load? A 3D echocardiographic multicentric study

Four‑Dimensional Echocardiographic Evaluation of Cardiac Iron Overload in Patients with Beta-Thalassemia Major

Cardiac magnetic resonance imaging is the gold standard to detect cardiac iron overload in patients with beta-thalassemia. The aim of this study was to evaluate cardiac iron overload using four-dimensional transthoracic echocardiography in thalassemia patients with and without cardiac involvement detected by T2* value and to compare the two techniques. This cross-sectional and observational study was conducted in 44 patients diagnosed with thalassemia major. Left ventricular systolic function was assessed using four-dimensional speckle tracking echocardiography-derived global longitudinal (GLS), circumferential, radial, and area strain indices. Left ventricular ejection fraction, volumes, and mass index were similar between the patients with T2* values less than 20 ms as compared to those with T2* values greater than 20 ms. However, patients with lower T2* values had significantly higher GLS values (- 17.0% vs. - 19.8%, p < 0.001) compared with those with higher T2* values. GLS demonstrated a sensitivity of 91.7% and a specificity of 71.9% at a cut-off value of - 18.5%; however, sensitivity was 75%, and the specificity was 84.4% at a cut-off value of - 17.5%. For - 18.5%, the positive predictive value was 55%, and the negative predictive value was 95.8%; for - 17.5%, these values were 64.2 and 90%, respectively. This novel echocardiographic method, tested for the first time in our study in comparison with cardiac MRI in an adult patient group, has been shown to predict cardiac iron overload in thalassemia patients in the subclinical period without LVEF decline. Four-dimensional GLS is a marker with high sensitivity and negative predictive value.

Revisiting the pathogenic role of insulin resistance in Duchenne muscular dystrophy cardiomyopathy subphenotypes

Introduction

Duchenne muscular dystrophy (DMD) is known to impact the subepicardial layer of the myocardium through chronic inflammation. Recent animal studies have shown predominant subendocardial involvement in rats with DMD. The primary outcome parameter was to determine by cardiovascular MRI (CMR) if two differential patterns of myocardial involvements exist in DMD; the secondary outcome parameters were to correlate the observed pattern with metabolic markers such as insulin resistance measures.

Methods

Forty patients with DMD were screened using CMR to determine which of them had predominantly subendocardial dysfunction (SENDO group), or subepicardial/midmyocardial involvement (SEPMI group). Patients were subjected to body mass index measurement, serum creatinine kinase, serum lactate dehydrogenase enzyme, fasting glucose-insulin ratio (FGIR), full lipid profile, left ventricular ejection fraction (LVEF), left ventricle E/E´ ratio (the ratio of early mitral inflow velocity to average early diastolic velocities of the basal septum and mitral annulus) for left ventricle diastolic function, and myocardial layer strain discriminating echocardiography (MLSD-STE). Results: 26 patients displayed SENDO while 34 displayed SEPMI. SENDO group displayed overt insulin resistance; (FGIR (SENDO: 7 ± 1 vs. SEPMI: 5 ± 1, P < 0.001). FGIR was negatively correlated with Subendocardial Global Longitudinal Strain (ENDO-LS) with r = -0.75.

Conclusion

DMD does not seem to influence the heart uniformly; DMD cardiomyopathy probably has two separate phenotypes with different mechanisms. Insulin resistance might be implicated in its pathogenesis and its reversal may help to slow disease progression.