I know this isn't a thread about panic attacks, but since it came up.....
Panic attacks can be triggered by thousands of different things (if anything at all!). The sight of a specific stimuli, certain smells,the temperature, different sensory experiences, a memory that comes to mind, etc. It can be anything!
In addition, the signs and symptoms of panic attacks are eerily similar to a heart attack. Sometimes it is hard to decipher if a person is having a panic attack or having a heart attack. Even if a person experiences panic attacks on a consistent basis, one might interpret his/her physical symptoms as a heart attack. In that moment of a panic attack, it is very scary and is usually threatening to a person's sense of safety.
It is very hard to watch someone having a panic attack. Imagine being the person that has one.
Just food for thought.