7 lines (6 with data), 252 Bytes

m224a 0 128 0 14:15:00 16/03/1991
# Start time=14:15
# First beat=14:15:00.171
# <age-range>: 60-64, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.492,  <RR-high-limit(sec)>: 1.265
# Note: recording with a timing signal, flutter-compensated