Altitude sickness in Vail, CO?

I moved to Boulder, CO elevation ~5,300 feet from sea level about 4 and a half months ago. I feel mostly acclimated except that stairs are sometimes a challenge. I can run on a treadmill for 40 minutes and feel fine (slightly out of breath) but stairs still get me sometimes. Anyway, I want to go to the Spring back to Vail festival next weekend, but I know Vail is at 8,000ish feet. I have a minor heart condition which made visiting Denver a little difficult (headache, slight nausea and pounding racing heartbeat) before moving, but am hoping since I am okay at 5,000 that 8,000 won't be that much more of a challenge. Am I wrong to think this?

Is it likely I'll have issues? Should I wait to book a hotel in case I need to go home that night? Thanks for any input. I know elevation sickness can start around 7,000 feet but since I'm already adjusted to 5,000 I'm wondering if that should help.


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Heating Vail Colorado