7 lines (6 with data), 252 Bytes

m283a 0 128 0 16:12:00 02/04/1991
# Start time=16:12
# First beat=16:12:21.257
# <age-range>: 45-49, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.507,  <RR-high-limit(sec)>: 0.937
# Note: recording with a timing signal, flutter-compensated