Correlation among Poincare plot indexes and time and frequency domain measures of heart rate variability

Primary objective: In order to corroborate the reported performance advantage of Poincare plot indexes as autonomic activity markers, the correlation among these indexes and those computed from the time and frequency domains were obtained. Methods and procedures: Starting from the RR series derived from the ECG of 21 healthy volunteers during five manoeuvres, longitudinal (L), transverse (T) axis, and autocorrelation (r) from Poincare plots, rMSSD and standard deviation (SD) in the temporal domain, and frequency domain indexes were computed. Main outcomes and results. Poincare plot indexes were correlated in a better way with the time indexes, rather than the spectral measures. A strong correlation (0.997) between L and SD was observed, while an underlying mathematical relationship was established for T vs rMSSD. Conclusions: Poincare plot indexes may be considered as equivalent or surrogates of the temporal ones, and they do not have a better performance as autonomic markers.