Objective : The aim of this study was to investigate whether cardiac autonomic function measuredby heart rate variability (HRV) indices are related to quality of life (QOL) improvements inpatients with acute myocardial infarction (AMI) treated by percutaneous coronary intervention.Methods : We enrolled 20 consecutive patients with AMI. Measures of HRV, obtained fromboth frequency and time domain analyses using 24-h Holter monitoring before discharge, were asfollows : low and high frequency (HF) domain measures, the square root of the mean squared differencesof successive R-R intervals (rMSSD), and the percentage of differences between adjacentnormal R-R intervals >50 ms for the whole analysis (pNN50). QOL was determined byphysical and mental component summary (PCS and MCS, respectively) scores derived from theJapanese Medical Outcomes Study 36-item Short Form Health Survey before and 6 months afterdischarge.Results : The subjects showed significant improvement in the MCS, but not the PCS score. There were also positive correlations between the parasympathetic parameters of HF, rMSSD,and pNN50 and the change in MCS score. In a multivariate analysis, rMSSD was found to beindependently associated with the change in MCS score.Conclusions : Parasympathetic tone, as measured by HRV, is independently associated withQOL, which emphasizes the role of cardiac autonomic function on QOL in patients with AMI
