7 lines (6 with data), 251 Bytes

m120a 0 128 0 10:00:00 21/05/1990
# Start time=10:00
# First beat=10:19:05.171
# <age-range>: 40-44, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.414,  <RR-high-limit(sec)>: 0.96
# Note: recording with a timing signal, flutter-compensated