What are my chances of going into cardiac arrest?

I'm a 17year old african american female, I'm about 5lbs overweight, I play soccer, I have had 2 normal ekgs and I have had a chest xray to show my heart was a normal size, I don't have high blood pressure or high chloseterol in fact both my blood pressure and cholesterol is very good, I don't have diabetes I do have ashtma I'm not taking any medication besides birth control. Please answer becaus e I'm a hypochondriac and I heard about brittany murphy dying suddenly of cardiac arrest and I got soo scared when I heard that , that I started feeling dizzy, plz help because she was only 32. Oh and no one in my family has ever died of cardiac arrest actually my family has a pretty long life span in fact my great grandma lived to be 105 and my granddad died at 92. Actually the youngest someone in my family has died of natural causes was my grandma at 60 of breat cancer. I have had some cousins die in there teens and 20's of car accidents but that's it. Please tell me my chances