LAUSR

This article refers to ‘Influence of ejection fraction on biomarker expression and response to spironolactone in people at risk of heart failure: findings from the HOMAGE trial’ by J.P. Ferreira et al. , published in this issue on pages 77 1 –778. The ejection fraction (EF) is the single most sought after num-ber in any echo report, but is frequently misinterpreted as being an index of left ventricular (LV) contractility. The EF when accurately measured using LV end-diastolic and end-systolic volumes, is merely the fraction of the end-diastolic volume (EDV) that is ejected per beat as the heart’s stroke volume (SV) [i.e. EF = SV/EDV]. Therefore following an acute myocardial infarct where there has not been time for LV remodelling, a decline in EF reflects acute cardiomyocyte loss and systolic dysfunction, and strongly predicts risk of heart failure (HF). Subsequent HF stud-ies then began to utilize a reduced EF (generally < 35%–40%) as entry criteria in efficient trials with high event rates, and resulted in the widespread use of EF to guide therapies in clinical practice. Although the EF works well to identify systolic dysfunction immediately post myocardial infarction, this is less true in the chronic setting. With chronic remodelling, the EF becomes uncou-pled from contractility, being also influenced by chamber remodelling and wall thickness. Moreover, the EF can be increased acutely by optimizing afterload, heart rate and preload without changes in underlying myocyte contractility. There is also substantial measurement variability that can result in clinically relevant reclassification