Left ventricular ejection fraction: are the revised cut-off points for defining systolic dysfunction sufficiently evidence based?
- G Mahadevan1,
- R C Davis2,
- M P Frenneaux1,
- F D R Hobbs3,
- G Y H Lip2,
- J E Sanderson1,
- M K Davies4
- 1Department of Cardiovascular Medicine, University of Birmingham, UK
- 2University Department of Medicine, City Hospital, Birmingham, UK
- 3Department of Primary Care and General Practice, University of Birmingham, UK
- 4Department of Cardiology, Queen Elizabeth Hospital, Birmingham, UK
- Dr G Mahadevan, Department of Cardiovascular Medicine, University of Birmingham, 21 Metchley Park Road, Edgbaston, Birmingham B15 2PQ, UK; devanm88{at}hotmail.com
- Accepted 19 June 2007
The recent guidelines from the American Society of Echocardiography and European Society of Echocardiography have defined an abnormal ejection fraction (EF) of the left ventricle, as one that is <55%.1 Owing to the fact that it is a continuous biological variable, there is inevitable debate over what constitutes mild, moderate and severe left ventricular (LV) dysfunction across the ranges of EF. Up to now, the lower limit of normal in clinical practice has usually been set at 40%.2
Despite the recent guidelines,1 there has been little debate or evidence to suggest altering the lower limit of normality to include patients with EFs of 50–54%. These guidelines therefore represent a step change in the definition of (echocardiographic) LV systolic dysfunction and will include many more patients into the category of “impaired LV function” with EFs >50%. The main limitation of this approach is how best to define risk. The cut-off points suggested for a single parameter can vary broadly for the risk of death, myocardial infarction, congestive heart failure and atrial fibrillation. Also, much of the literature applies to specific populations (eg, after myocardial infarction, the elderly) and not to overall cardiovascular risk.1
The recommended new cut-off EF value of 54% is based on expert opinion, interpreting data from the limited number of studies that have reported that an EF <54% is associated with moderate adverse outcomes.1 For example, Roman et al followed up 486 patients undergoing echocardiography to determine the prevalence of carotid atherosclerosis and to examine its relationship to LV hypertrophy.3 Two hundred and seventy-seven subjects were normotensive and 209 subjects had untreated hypertension, and all were asymptomatic with no overt manifestations of cerebrovascular disease. The investigators found that 392 patients were essentially without any evidence of carotid plaques and 366 patients had …
