Yes I have felt as though I was having a heart attack. Heart palpitations are a significent symptom of anxiety. My mind is conditioned to notice those palpitations more intensely and immediately think the worse. However, the 50 times I have felt these symptoms, I have never had a heart attack, and nor will i. It's just the fear. ...And like you, I have escaped to the restroom many times in my life to sit and meditate or seek guidance and strength until I am alright enough to get back out there. The problem with anxiety is that it feeds on itself. Once you have felt a fear, your mind will manipulate even the most minimal symptom, and morph it into the worst thing imaginable. That's what I mean by feeding on itself. It grows if you let it. If and when you are able, I would recommend staying where you are rather than going to the restroom. I know that sounds impossible. But, give yourself permission to feel uncomfortable in whatever situation you are faced with. I do this practice regularly in restaurants and certain public places. Rather than going into the restroom, I sit and allow my mind and body to express anxiety. I feel the palpitations, I breathe heavily, break into a sweat, feel dizzy and light-headed. Because I have given my mind permission, it desolves quicker. It reappears sometimes, but again it dissolves. It's a repetitive practice, but I feel less like I am fighting an insurmountable obstacle. If you are unable to stay where you are, you still have that option to escape to the restroom or to leave the situation entirely. That is ok too, because that is also an option you have. Give yourself permission. I think that's the key.