I haven't tried meth, but I have the same problem with amphetamines in general. That horrible heart-focused panic. Fuckin awful. Worth the high, but awful while it's happening. Drinking it off always helps a ton with me. Alcohol is technically "bad" for your heart, but I think only in the long-term. For a night of panic, I feel like it's perfectly fine. Just have a few drinks, think calm thoughts and remember that odds are overwhelmingly high that you'll be completely fine. Also, benedryl. Always helps me sleep off the panic.
Oh, and drinking lots of water usually helps me ease comedown anxiety!