7 lines (6 with data), 254 Bytes

m264a 0 128 0 12:45:00 22/10/1990
# Start time=12:45
# First beat=12:53:13.304
# <age-range>: 70-74, <sex>: Female, <medication>: None
# <RR-low-limit(sec)>: 0.703,  <RR-high-limit(sec)>: 1.195
# Note: recording with a timing signal, flutter-compensated