EF, or LVEF, is short for Left Ventricular Ejection Fraction, and is a percentage expression of the pumping ability (strength) of the heart, specifically the left ventricle, which pumps the oxygenated blood out of the heart and into the body. A normal ejection fraction is between 60% and 70%. Heart failure (a "weak heart") is classified as an EF less than 40%. The good news is, if you didnt get a whole heap of information and teaching on heart failure before you left the hospital, then you probably dont have it. As for the circ blockage affecting the left side of the heart, there is a good chance there was no damage done to the heart muscle, because even though a 70% blockage sounds like a lot, most interventionalist wont intervene on a blockage until its greater than 60% occluded. Also the fact that your EKG's were normal is a good sign no long-term damage was done. But as always, I'd double check with the MD that did the intervention.
Jordan.