Heart rate and energy consumption

Springerrr

I use a Cybex elliptical at the gym. I am not a super athlete. I get my heart-rate up to ~150 and hold it there for ~45m. At the end of the workout the gizmo tells me I’ve burned ~800 cal -- equivalent to an 6 mile run (which would take me an hour)!! When I run my heart rate is likely to be about the same, suggesting the same metabolic burn-rate, but it would take me 60 min to burn 800 cal, assuming my slow 10 min miles.

Does heart-rate correlate with metabolism?