7 lines (6 with data), 257 Bytes

m261b 0 128 0 8:40:00 08/03/1991
# Start time=08:40
# First beat=08:48:00.351
# <age-range>: 50-54, <sex>: Male, <medication>: Moricizine
# <RR-low-limit(sec)>: 0.492,  <RR-high-limit(sec)>: 1.304
# Note: recording with a timing signal, flutter-compensated