7 lines (6 with data), 252 Bytes

m165a 0 128 0 14:15:00 05/10/1990
# Start time=14:15
# First beat=14:23:28.500
# <age-range>: 70-74, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.593,  <RR-high-limit(sec)>: 1.085
# Note: recording with a timing signal, flutter-compensated