I had the same thing happen to me.. But not the heart part. When my period came it was already at the end of my dry fast… but after my period did not return until almost two months. I don’t know if it was the rapid weight loss or rapid weight gain at the end of the fast that caused me to lose it which is most likely since I lost 10lbs in 5 days and regained them in the same time period. For you, everyone is different so you may not lose your period. But if your heart is getting too stressed out then I think you should know when to stop.