Panic attacks can be terrifying. The first time that I had a panic attack I was pretty convinced that I was about to die. Many people have ended up in hospital emergency rooms because they mistook their panic attack symptoms for heart attacks. The symptoms can be similar. People often experience frightening symptoms such as chest pains, rapid heart beat, or shortness of breath. But, assuming you've been seen by a doctor and deemed healthy, you probably don't have much to worry about.
Your panic attack itself does not have the ability to kill you. There is one simple reason behind this. The panic attack itself is created by your body. It is a natural reaction to a perceived threat that starts in your amygdala as a defense mechanism. It may be misdirected. It may be unwanted at that time, but it's primary purpose is to protect you from danger. Your internal body does not have the ability to self destruct.
Don't believe me? Think about your heartbeat and try to make it stop. It can't be done. Likewise, you cannot will yourself to stop breathing. You can hold your breath, sure. But eventually, no matter how hard you fight it, your breathing will continue. You body and mind have the power to do many amazing things but willingly shutting themselves down is not one of them.
Once you realize this, you can take a lot of the wind out of your panic attack's sails. Your fear will decrease and it's really your fear that feeds the panic attack monster. Stop feeding it and it will go away. It's like when you were a kid and afraid of the boogeyman in your closet at night. You were scared, sure that whatever this horrible creature was lurking in the dark was going to get you at any minute. You screamed for your parents and they come and turn on the lights, and you see that the "boogeyman" was all along just one of your toys with a blanket draped over it. The fear goes away.