7 lines (6 with data), 250 Bytes

m051a 0 128 0 10:35:00 21/03/1991
# Start time=10:35
# First beat=10:59:01.742
# <age-range>: 65-69, <sex>: Female, <medication>: None
# <RR-low-limit(sec)>: 0.515,  <RR-high-limit(sec)>: 1.015
# Note: reel-to-reel recording, not flutter-compensated