7 lines (6 with data), 260 Bytes

m053b 0 128 0 12:25:00 30/08/1990
# Start time=12:25
# First beat=12:33:02.773
# <age-range>: 50-54, <sex>: Female, <medication>: Moricizine
# <RR-low-limit(sec)>: 0.421,  <RR-high-limit(sec)>: 0.796
# Note: recording with a timing signal, flutter-compensated