Comparison of the ratio of the standard deviation of the R-R interval and the root mean squared successive differences (SD/rMSSD) to the low frequency-to-high frequency (LF/HF) ratio in a patient population and normal healthy controls.

Heart rate variability (HRV) analysis involves examining the normal rhythmic fluctuations in heart rate using statistical indices (e.g. standard deviation, root mean square of the successive differences) or more complex spectral analytic techniques. Recently, Balocchi et al (2006) found that the ratio of the standard deviation of the r-r interval (SD) over the root mean squared of the successive differences (rMSSD), a simple statistical index, could be used as a surrogate for the low-to-high frequency ratio (LH/HF) typically calculated from the spectral estimates. We sought to extend this work by examining a patient population. Results indicate that the SD/rMSSD ratio is a good surrogate for the LF/HF ratio across multiple contexts in both patients and normal healthy controls.