7 lines (6 with data), 251 Bytes

m131a 0 128 0 9:00:00 03/03/1991
# Start time=09:00
# First beat=09:06:33.671
# <age-range>: 50-54, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.421,  <RR-high-limit(sec)>: 0.828
# Note: recording with a timing signal, flutter-compensated