Distinct Echocardiographic Phenotypes in Primary vs. Secondary Iron Overload Cardiomyopathy: A Pilot Study on Myocardial Work Indices.

Background

Iron overload cardiomyopathy (IOC) is a major determinant of outcomes in hemochromatosis, and conventional echocardiography may miss early myocardial toxicity. Comparative data on primary (PH) versus secondary hemochromatosis (SH) using myocardial work (MW) indices are limited.

Methods

We performed a retrospective cross-sectional study of 34 adults (16 PH and 18 SH patients) at a tertiary center. They all underwent echocardiography with speckle-tracking to obtain LV global longitudinal strain (GLS) and non-invasive MW indices from pressure-strain loops: global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE). Echocardiographic phenotypes were classified as a Normal, Dilated, Restrictive, or right ventricular/pulmonary hypertension (RVPH) phenotype.

Results

SH patients showed higher iron burden and neurohormonal activation than PH patients (maximum ferritin 2954 vs. 444 ng/mL; BNP 93 vs. 13.5 pg/mL; both p < 0.001) and accounted for all deaths (33% vs. 0%) despite similar 3D LVEFs and GLSs. PH patients predominantly exhibited Normal phenotypes (81%), whereas SH patients more often showed advanced phenotypes, mainly RVPH and Dilated. GWI correlated inversely with ferritin (ρ ≈ -0.40), particularly ferritin at echocardiography in SH patients, while PH patients showed no significant correlations. GWW was higher in Dilated/RVPH compared to Normal phenotypes, and in SH patients, higher maximum ferritin was associated with impaired right ventricular free-wall strain.

Conclusions

PH and SH patients exhibit distinct IOC phenotypes, with SH patients showing more advanced remodeling and worse outcomes. In this exploratory analysis, MW indices showed modest associations with iron burden markers, suggesting they may provide complementary information beyond LVEF and GLS. These preliminary findings require validation in larger, prospective studies.