7 lines (6 with data), 252 Bytes

m287a 0 128 0 12:00:00 03/09/1990
# Start time=12:00
# First beat=12:00:02.421
# <age-range>: 65-69, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.492,  <RR-high-limit(sec)>: 0.906
# Note: recording with a timing signal, flutter-compensated