7 lines (6 with data), 251 Bytes

m229a 0 128 0 8:40:00 18/12/1990
# Start time=08:40
# First beat=08:51:48.187
# <age-range>: 70-74, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.515,  <RR-high-limit(sec)>: 0.859
# Note: recording with a timing signal, flutter-compensated