Latest British Society of Echocardiography recommendations for left ventricular ejection fraction categorisation: potential implications and relevance to contemporary heart failure management.

We read with interest the recent guideline publication from the British Society of Echocardiography (BSE) relating to normal reference intervals for cardiac dimensions and function for use in echocardiographic practice (1). We commend the authors and the Education Committee for attempting to produce updated guidance taking into account contemporary, prospective data to determine new reference ranges for echocardiographic parameters. However, we suggest the newly proposed categories for left ventricular ejection fraction (LVEF) derangements from the BSE may contribute to diagnostic and therapeutic uncertainty and create new challenges for the management of heart failure (HF) patients in the United Kingdom (UK). It is well recognised that HF transitions across the spectrum of LVEF and irrespective of LVEF, and that the prognosis for patients with HF is worse than in those without this diagnosis. Moreover, recent evidence points to adverse outcomes even in the setting of ‘supra-normal’ LVEF (2). As addressed in the recent publication (1), the latest BSE guidance for LV function categorisation (‘severely impaired’, LVEF ≤35%; ‘impaired’, LVEF 36–49%; ‘borderline low’, LVEF 50–54%; and ‘normal’, LVEF ≥55%) is clearly out of keeping with current guideline documents from international echocardiographic societies (American Society of Echocardiography (3), European Association of Cardiovascular Imaging (4)) and with those from international cardiology societies in Europe (European Society of Cardiology (ESC) (5)) and North America (American College of Cardiology/American Heart Association (6)). Both the ESC and the AHA define (heart failure with reduced ejection fraction) HFrEF at, or below, 40%. The ESC and AHA HF diagnostic thresholds have been reached not just on the basis of prognosis alone. Both heart failure with mid-range ejection fraction (HFmrEF) and heart failure with preserved ejection fraction (HFpEF) groups are characterised by marked heterogeneity and display differing epidemiological and pathophysiological profiles compared to HfrEF (7, 8, 9, 10). While the BSE document suggests that LVEF displays a continuous relation to prognosis ‘i.e. as the LVEF gets progressively lower, survival is progressively poorer’, LVEF exhibits a U-shaped, rather than a linear, relation to mortality (2). Both HFrEF and those with supra-normal LVEF are associated with the highest degrees of mortality, albeit HFmREF and HFpEF patients have poor prognosis relative to those without HF (11). Current ESC HF diagnostic thresholds have been conceived on the basis of evidence-based treatment response, with the demonstration in multiple clinical -20-0029 ID: 20-0029