7 lines (6 with data), 252 Bytes

m174a 0 128 0 17:15:00 25/12/1989
# Start time=17:15
# First beat=17:22:33.375
# <age-range>: 55-59, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.453,  <RR-high-limit(sec)>: 1.023
# Note: recording with a timing signal, flutter-compensated