The association between heart rate variability (HRV) and an average heart rate (HR) is partly mathematically determined due to the non-linear (mathematical) relationship between RR interval (RR) and HR.Correction of RRs with respect to the average RR (i.e.calculation of corrected HRV) may remove this mathematical influence on HRV.Recently,we have shown that corrected HRV indices exhibit higher reproducibility than classical ones.However, our further analyses carried out on 1455 post-infarction patients (followed up for 5 years) revealed weaker prognostic power of corrected HRV comparing with classical HRV.We demonstrate that the average HR must contribute to the prediction power of HRV-this contribution is mathematically amplified in classical HRV analysis which results in its higher prognostic power in post-infarction patients.Our studies clarify some aspects of the association between HRV and an average HR.