7 lines (6 with data), 250 Bytes

m145b 0 128 0 10:15:00 26/05/1989
# Start time=10:15
# First beat=10:19:54.539
# <age-range>: 45-49, <sex>: Male, <medication>: Moricizine
# <RR-low-limit(sec)>: 0.523,  <RR-high-limit(sec)>: 1
# Note: reel-to-reel recording, not flutter-compensated