7 lines (6 with data), 246 Bytes

m123a 0 128 0 10:39:00 06/06/1991
# Start time=10:39
# First beat=10:41:25.726
# <age-range>: 70-74, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.5,  <RR-high-limit(sec)>: 1.632
# Note: reel-to-reel recording, not flutter-compensated