7 lines (6 with data), 250 Bytes

m214a 0 128 0 8:20:00 31/12/1989
# Start time=08:20
# First beat=08:20:00.593
# <age-range>: 70-74, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.687,  <RR-high-limit(sec)>: 0.96
# Note: recording with a timing signal, flutter-compensated