Reliability of ultra-short indices for autonomic dysfunction in dyslipidemia

Dyslipidemia is associated with autonomic nervous system (ANS) dysfunction. Heart rate variability (HRV) is a powerful tool for evaluating the ANS and for cardiovascular risk stratification. Yet, the methodologies used are impractical in most clinical settings and therefore, are usually not applied. The current study aimed to evaluate the reliability of ultra-short HRV parameters, which are easily calculated from any standard ECG, as a practical method for ANS study, with a focus on patients with dyslipidemia. Fifty-nine volunteers with dyslipidemia underwent HRV study of parametric and power spectral indices according to accepted methods. Correlations were calculated between ultra-short HRV indices (five 1-min and five 10-s segments) and standard 5-min recordings. Correlations were found between 10-s and 1-min RMSSD and 5-min recordings (mean Pearson ρ correlation coefficients of 0.913 and 0.944, respectively, and mean concordance correlation coefficients of 0.855 and 0.938, respectively). Associations were found between other ultra-short HRV parameters (SDNN, maximum RR, minimum RR, pNN50, ln(RMSSD) and 5-min recordings. In addition, average RR, HRV-TI, NN50, TP, LF/HF, ln(SDNN), ln(HRV-TI), ln(TP) and ln(LF/HF) from 1-min recordings were associated with 5-min values. In conclusion, some ultra-short HRV parameters can be used for ANS evaluation and presumably, for cardiovascular risk stratification among patients with dyslipidemia. These parameters seem to be of great practical value for both inpatient and outpatient settings, because most can be calculated from a standard 10-s ECG strip. The prognostic implications of ECG-derived, ultra-short HRV parameters in patients with dyslipidemia should be further evaluated in future studies.