7 lines (6 with data), 258 Bytes

m253b 0 128 0 14:00:00 13/07/1989
# Start time=14:00
# First beat=14:00:00.585
# <age-range>: 45-49, <sex>: Male, <medication>: Moricizine
# <RR-low-limit(sec)>: 0.601,  <RR-high-limit(sec)>: 1.281
# Note: recording with a timing signal, flutter-compensated