Agree with Matiadbueno94. EF is your Ejection Fraction. When your heart beats it first fills with blood, it then squeezes out that blood. Normally about 66% gets squeezed out. This is call the Ejection Fraction. Usually anything over 55% is considered "normal". If it's to high your heart may be working to hard so you need to look at heart rate and blood pressure as well. DISCLAIMER: I am not a doctor. I am not qualified to provide medical advice. I am only trying to provide information for you to research further.