Can someone help my friend overcome his phobia of sudden cardiac arrest?

Hi, my friend is 18 years old and started freaking out recently over having a sudden cardiac arrest. He is always scared to go out or anywhere now. He had like 4 EKGs (because he was having heart pains) which came back fine, had an echo stress test which came back fine, has no family history of heart problems like that, and doesn't smoke but is a little overweight. Can someone please help me convince him that hes not going to drop dead from a cardiac arrest or heart attack please, some good hard solid facts would help out a lot since he's a very scientific guy. Thanks ahead.