The Relationship Between Heart Rate Turbulence And Heart Rate Variability

Objective: Heart rate variability(HRV) is one of the established predictors for sudden cardiac death(SCD) in patients after myocardial infarction or with heart failure,but its ability of predicting mortality has weakened in β-blocker era.Heart rate turbulence(HRT) has been demonstrated a new stronger mortality-predictor than other available predictors such as HRV,LVEF≤40% and electrophysiologic test.This study was designed to investigate the correlation between indices of HRV and HRT.In parallel,we also explored the impact of mean R-R interval, β-blocker and other factors on HRV and HRT. Methods:56 postinfarction patients were recruited. 24-hour ,three-lead ambulatory electrocardiography was performed in all subjects for the analysis of HRV(including SDNN, PNN50,SDANN, RMSSD,HF,LF) and HRT(including TO and TS). And the general clinical data of each case were collected. Results: There was a positive correlation between TS and SDNN (r=0.559,P<0.001),and PNN50 (r=0.511,P<0.001),and SDANN (r=0.552,P<0.001),and RMSSD (r=0.515,P<0.001),and HF (r=0.644,P<0.001). TO inversely correlated with SDNN (r=-0.524,P<0.001),PNN50 (r=-0.511,P<0.001),SDANN(r=-0.538,P<0.001),LF(r=-0.543,P<0.001),HF(r=-0.412,P<0.001) ,TS (r=-0.349,P<0.05). Both TO and TS had no correlation with the variables such as the treatment of β-blocker,mean R-R intervals,LVEF,concomitant hypertension,but there was a weak correlation between SDNN and each one of these variables. There was a moderate association between SDNN>100ms ,TO<0 and TS>2.5ms/RR. Conclusions:1.There is a close positive correlation between TS and some parameters signifying the vagal tone such as PNN50,RMSSD and HF,which suggests TO is mainly associated with the cardiac vagal efferent activity.2. TO may be modulated by both sympathetic and parasympathetic efferent activity.3. HRT is not influenced by such factors as treatment of β-blocker,mean R-R intervals, LVEF, concomitant hypertension, which may explain the reason why HRT is superior to HRV in predicting high-risk patients of SCD.