When was your EF measured? Before or after your PTCA? This is important because sometimes, if the PTCA was done shortly after your heart attack, a lot of the heart function may recovered after the procedure. For example, if your EF is 30% before the PTCA, it may be 40% afterwards. It may takes time to see the improvement, ranging from days to weeks. This phenomenon is called "stunning" -- like a person who got hit and and passed out for a moment but recovers his consciousness after a period of time. In general, right after a heart attack, a patient should rest for the first month without strenuous exercise. It is like if you injured your foot, you don't want to go back exercising right away until it is well healed. To start, you can walk slowly for 1/2 hour and gradually increase your pace. Obviously, do stop if you feel bad and consult your doctor. In general, exercise does not directly improve heart muscles that have already been permanently damaged. Its benefits derive mostly from its effects on heart musclesthat have not been damaged and on the rest of the body in general.
Contrary to popular belief, it would appear that rest is more beneficial to heart recovery than exercise when low EF is associated. In the UK, patients with an EF less than 30% are usually given an ICD because arrhythmia is more likely. This acts as a stop gap while they wait for a transplant. I am speaking of those with irreversible damage, ie areas of heart muscle have died. Many of those patients have seen quite dramatic increases in EF. There was also a case of a young girl a while back who had very low EF and they transplanted a heart into her body, but left her own heart in place (stopped). They had no idea why her heart wasn't working very well. After three months, they stopped the donated heart and restarted her own. It immediately began to work properly and the conclusion was that it simply needed a rest. Yes we see people improve EF through exercise sometimes, but we could ask "was it the exercise at all". How can you prove it.