• Cardiomyopathy, Hypertrophic
• Echocardiography

In stark contrast to the more commonplace cardiac diseases, such as heart failure (HF), valvular heart disease or coronary artery disease, it might appear that systolic function, typically expressed as an ejection fraction (EF), is of lesser importance in hypertrophic cardiomyopathy (HCM). The predominant view has been that EF is either normal or super-normal in HCM, and that it is only in a minority of patients, those in ‘end-stage’ HCM phase, where systolic function becomes salient as a clinically relevant issue. Oversimplified though this may be, it would now appear, based on recent findings, that systolic function might not be such a niche subject in HCM after all.

hoi et al from two tertiary centres from Seoul, South Korea present their highly intriguing findings on the potential significance of ‘borderline’ or ‘low-normal’ EF in HCM.1 Based on EF measurements, 1858 patients with ‘true’ HCM (excluding HCM phenocopies, such as Fabry disease, glycogen storage disease, amyloidosis, etc) were stratified into: preserved EF (≥60%; n=1399), ‘borderline’ EF (50%–60%; n=421) and reduced EF (<50%; n=44) subgroups. The findings of Choi et al indicated that patients with ‘borderline’/‘low-normal’ EF were characterised by certain distinct clinical features as well as being at an increased risk of HF hospitalisation and cardiovascular death in comparison with those with preserved EF. Moreover, sudden cardiac death (SCD) was also associated with EF.

Clearly, these findings warrant further commentary and contemplation. First of all, let us remind ourselves that two slightly different approaches to the definition of HCM are currently endorsed by the leading American and European societies. The American guidelines underline the genetic and more precisely—sarcomeric nature of HCM in the diagnostic work-up, whereas in the European approach, ‘no a priori assumptions about aetiology or myocardial pathology’ are made.2 3 Here, the authors took the American route …