Power Spectral Analysis of Heart Rate Varability in Sudden Cardiac Death: Comparison to Other Methods

Power spectrum analysis of heart rate variability is described and compared to four other reported methods, with respect to their efficacy as predictors of risk of sudden cardiac death (SCD). Approximate frequency domain representations were obtained for each. The underlying physiologic processes which may give rise to spectral components are considered. These methods were employed to analyze 24-h ambulatory ECG's of patient populations at different degrees of risk of SCD. Heart rate variability was found to be reduced in cardiac patients known to be at increased risk of SCD, when compared to those not at increased risk. These differences were greatest in power spectral methods. Thus, power spectrum analysis appears to be more effective than the other methods in segregating these populations, suggesting that this method may be useful in categorizing cardiac patients according to risk of sudden cardiac death.