Correlation between power-law behavior and Poincare plots of heart rate variability in congestive heart failure patients

Nonlinear analysis of HRV, particularly 1/f method and Poincare plots, has been recognized to provide valuable information for the prognostic stratification in cardiac patients. We analyzed 24h ECG Holter recordings in 75 CHF patients to assess (1) the correlation between power-law and both qualitative and quantitative indexes of abnormality of Poincare plots, and (2) the association between the two nonlinear indexes and hemodynamic function, exercise performance and neurohumoral activation. We found a clear association between 1/f slope and the visually-classified shape of Poincare patterns but just a poor correlation between 1/f indexes and morphological parameters of Poincare maps. Moreover 3D Poincare parameters were shown to be independently associated to plasma norepinephrine level, indicating that they "contain" the information of 1/f indexes and better explain norepinephrine variability.