7 lines (6 with data), 252 Bytes

m268a 0 128 0 14:30:00 12/02/1990
# Start time=14:30
# First beat=14:38:14.945
# <age-range>: 75-79, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.492,  <RR-high-limit(sec)>: 1.359
# Note: recording with a timing signal, flutter-compensated