7 lines (6 with data), 251 Bytes

m250a 0 128 0 10:30:00 04/05/1991
# Start time=10:30
# First beat=10:38:23.695
# <age-range>: 55-59, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.515,  <RR-high-limit(sec)>: 1.21
# Note: recording with a timing signal, flutter-compensated