7 lines (6 with data), 252 Bytes

m137a 0 128 0 14:10:00 05/09/1990
# Start time=14:10
# First beat=14:10:00.546
# <age-range>: 35-39, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.429,  <RR-high-limit(sec)>: 1.148
# Note: recording with a timing signal, flutter-compensated