7 lines (6 with data), 260 Bytes

m264b 0 128 0 12:40:00 24/11/1990
# Start time=12:40
# First beat=12:48:04.976
# <age-range>: 70-74, <sex>: Female, <medication>: Moricizine
# <RR-low-limit(sec)>: 0.718,  <RR-high-limit(sec)>: 1.187
# Note: recording with a timing signal, flutter-compensated