7 lines (6 with data), 252 Bytes

m180a 0 128 0 10:45:00 18/03/1990
# Start time=10:45
# First beat=10:54:31.484
# <age-range>: 70-74, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.648,  <RR-high-limit(sec)>: 1.125
# Note: recording with a timing signal, flutter-compensated