Frequency domain measures of heart period variability to assess risk late after myocardial infarction

AbstractObjectives. To determine whether spectral measures of heart period (RR) variability predict death when measured late after infarction, we studied patients in the Cardiac Arrhythmia Pilot Study (CAPS) who survived for 1 year and had a 24-h electrocardiographic (ECG) recording made after the CAPS drug wa, washed out.Background. Four components of the heart period power spectrum—ultra low frequency (<0.0033 Hz), very low frequency (0.0033 to <0.04 Hz), low frequency (0.04 to <0.15 Hz) and high frequency power (0.15 to <0.40 Hz)—plus total power (1.157 x 10−5to <0.40 Hz) and the ratio of low to high frequency power predict mortality when measured