7 lines (6 with data), 250 Bytes

m031a 0 128 0 10:15:00 19/03/1989
# Start time=10:15
# First beat=10:15:22.914
# <age-range>: 60-64, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.5,  <RR-high-limit(sec)>: 1.015
# Note: recording with a timing signal, flutter-compensated