7 lines (6 with data), 251 Bytes

m290a 0 128 0 9:57:00 23/07/1990
# Start time=09:57
# First beat=09:58:03.585
# <age-range>: 60-64, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.406,  <RR-high-limit(sec)>: 0.781
# Note: recording with a timing signal, flutter-compensated