7 lines (6 with data), 247 Bytes

m277a 0 128 0 8:00:00 25/09/1992
# Start time=08:00
# First beat=08:18:56.765
# <age-range>: 55-59, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.546,  <RR-high-limit(sec)>: 1.015
# Note: reel-to-reel recording, not flutter-compensated