I Had A Heart Failure After A Heart Attack Happened

I had a heart failure after a heart attack happened in November 2014. I was told that my Left main valve has been blocked after stent done in November 2014. I have undergone a three vessal by-pass to repair the blocked left valve on 1 September 2015. My ejection fraction at that was about 30to 35. After the by-pass it was about 35%. Then I had a eco-cardiogram in 4 January 2016 in Sri Lanka and my ejection fraction was 35-40%. Then I had a echocardiogram and nuclear stress test on 12 Feb 2016 and I was told that my ejection fraction is now 31%. Is there a possibility that my ejection fraction improves after by-pass surgery in the long rum.