Severe damage to the heart muscle as manifested by recurrent heart failure or other indications of left ven¬tricular dysfunction and an EF of less than 30% is a major contraindication for bypass graft surgery. Such patients are very short of breath and often have fluid in the lungs. Shortness of breath cannot be relieved by surgery, and the heart muscle is not significantly strengthened for surgery.
Several heart attacks cause large areas of scarring, and the scar tissue is weak. Scar tissue is dead and not supplied with blood; therefore, a bypass graft does not feed blood to that area. Heart failure in the presence of an acute heart attack that clears within the first seven days is not a contraindication to bypass surgery several months later, because the heart muscle recovers more than 75% of its function.