7 lines (6 with data), 253 Bytes

m246a 0 128 0 10:15:00 08/03/1988
# Start time=10:15
# First beat=10:15:17.804
# <age-range>: 70-74, <sex>: Female, <medication>: None
# <RR-low-limit(sec)>: 0.46,  <RR-high-limit(sec)>: 1.117
# Note: recording with a timing signal, flutter-compensated