They run fast for a person w/ heart disease, yes, but it’s unclear (c.1983) as to the contributing factors. Their LT is normal but their VO2max is compromised, so comparatively they run slow yet still trigger the VO2max adaptations.
(previous posted link may not work, try this one: http://scholar.google.ca/scholar_url?url=http://www.academia.edu/download/44270475/Blood_lactate_threshold_in_some_well-tra20160331-338-139eymj.pdf&hl=en&sa=X&scisig=AAGBfm1vEjhl4-QBmLMXmvjHDEUa_mmoOQ&nossl=1&oi=scholarr )