7 lines (6 with data), 258 Bytes

m258b 0 128 0 11:23:00 05/04/1989
# Start time=11:23
# First beat=11:31:20.453
# <age-range>: 50-54, <sex>: Male, <medication>: Moricizine
# <RR-low-limit(sec)>: 0.507,  <RR-high-limit(sec)>: 0.984
# Note: recording with a timing signal, flutter-compensated