Left-sided mastectomy mimics LVEF decline on CZT-ERNA: a consideration for cardio-oncology practice

BACKGROUND: Monitoring of left ventricular ejection fraction (LVEF) is essential in patients receiving potentially cardiotoxic cancer therapies. Equilibrium radionuclide angiography (ERNA) remains an established method for quantitative assessment of LVEF. However, the absence of attenuation correction may render the method sensitive to anatomical changes, such as those caused by mastectomy. The aim with this study was to investigate whether left-sided mastectomy systematically affects the estimation of LVEF using cadmium-zinc-telluride (CZT)-based ERNA. METHODS: This retrospective single-centre cohort study included breast cancer patients who had undergone unilateral or bilateral mastectomy and had both pre- and postoperative CZT-ERNA performed under identical acquisition protocols. Pre- to postoperative changes in LVEF, left ventricular end-diastolic volume (LVEDV), and left ventricular end-systolic volume (LVESV) were compared between left- and right-sided mastectomy groups. RESULTS: Between-group comparison showed that left-sided mastectomy (including bilateral) was associated with a significant decrease in LVEF (mean change -4.0 percentage points, 95% CI -6.0 to -2.0, p = 0.011). In contrast, no significant within-group change was observed for right-sided mastectomy (mean change 0.6 percentage points, 95% CI -2.4 to 3.6, p = 0.7). One in four patients (25%) in the left-sided group experienced a decline in LVEF of at least 10 percentage points, compared with 1 in 17 in the right-sided group. Multivariable regression analysis indicated that LVEF decline was independently associated with mastectomy laterality, whereas cumulative anthracycline dose and radiotherapy were non-significant. CONCLUSION: Left-sided mastectomy is associated with a significant decrease in LVEF measured by CZT-ERNA. This finding likely reflects improved delineation of LVESV rather than true systolic decline. Recent chest surgery and individual anatomical changes should be considered when interpreting serial CZT-ERNA examinations. Confirmatory imaging may be warranted in cases of unexpected or pronounced LVEF declines.