7 lines (6 with data), 254 Bytes

m280a 0 128 0 15:25:00 24/12/1990
# Start time=15:25
# First beat=15:29:36.078
# <age-range>: 70-74, <sex>: Female, <medication>: None
# <RR-low-limit(sec)>: 0.554,  <RR-high-limit(sec)>: 1.109
# Note: recording with a timing signal, flutter-compensated