7 lines (6 with data), 248 Bytes

m125a 0 128 0 11:07:00 10/05/1991
# Start time=11:07
# First beat=11:08:47.023
# <age-range>: 70-74, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.773,  <RR-high-limit(sec)>: 1.382
# Note: reel-to-reel recording, not flutter-compensated