7 lines (6 with data), 246 Bytes

m285a 0 128 0 10:00:00 25/07/1989
# Start time=10:00
# First beat=10:03:54.664
# <age-range>: 50-54, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: NA,  <RR-high-limit(sec)>: NA
# Note: recording with a timing signal, flutter-compensated