Hello there and congratulations!
You are one of the bright examples here on this forum.
You certainly did not damage your heart. However during fasts, eating some and back and forth is in general not advisable, since it confuses the system. Then the risk of getting into starvation and loosing healthy tissue substance is greater.
EKG was normal - great. It is not 100% sensitive though and if an arrhythmia is present once in a while it is not a reliable exclusion test.
I understand that you worked all along, so it is close to mind that doing 40 days water only is difficulty not to say impossible deed, that you were able to withstand by consuming ... (you did not specify what). If you decide to do another long fast, however, I hope you give yourself a break from intense occupations, since anyway the risk is much higher when you don't rest and further if you consume food here and there.