| Objective To explore the changes and clinical significance of heart rate turbulence(HRT) in patients with acute coronary syndrome(ACS).Methods 67 ACS patients and 40 healthy persons were recruited respectively as the ACS group and the control group .The healthy persons had ventricular premature beats but structurally normal hearts. Dynamic electrocardiogram(DCG) and the Ultrasonic Cardiogram(UCG) were performed in all subjects for the analysis of numbers of ventricular premature complexes per 24h,the mean heart rates per 24h, standard deviation of all normal to normal RR intervals(SDNN),TO(Turbulence Onset), TS(Turbulence Slope),left ventricular ejection fraction(LVEF) and LVEDD. According to Schmidt,s advice,the abnormal cut points of TO and TS were set as TO≥0 and TS≤2.5ms/RRI,respectively and patients were classified into the following HRT categories: HRT category 0 if both TO and TS were normal,HRT category 1 if either TO or TS was abnormal,HRT category 2 if both TO and TS were abnormal .The general clinical data of each case were recorded. The endpoint events include ventricular malignant arrhythmias,cardiogenic shock,heart failure or sudden cardiac death(SCD) in hospital and rehospitalization because of reinfarction or angina pectoris or heart failure and SCD during follow-up period. According to the results of follow-up, ACS patients were divided into two groups (the high-risk group and the low-risk one).The variables of every two groups were compared and then analyzed to assess the prognostic value for risk stratification.Results (1) The value of TO was significantly higher(0.36×10-2±3.76×10-2 vs -1.80×10-2±2.76×10-2,P<0.001) and TS was significantly lower(4.95±6.78 vs12.43±7.29ms/RRI,P<0.001)in the ACS group than those of the control group. HRT positive rate of the ACS group was much higher than that of the control group [80.60(54/67)%vs17.50%(7/40),P<0.001].(2)The TS of the AMI subgroup was much lower than that of the UAP subgroup(4.29±3.68 vs 8.30±8.76ms/RRI,P<0.05). TS positive rate was much higher than that of the UAP subgroup[45.95%(17/37) vs16.67%(5/30),P<0.05], as was the case in HRT positive rate[86.49%(32/37)vs73.33%(22/30), P<0.05]. However, there wasn't statistic difference in TO between these two groups,neither did TO or HRT positive rate (P >0.05).(3)During a median follow-up of 6.5 months, 39 patients caught cardiac events. The TS of the high-risk group was much lower than that of the low-risk group(4.86±4.82 vs 6.75±6.90 ms/RRI, P<0.05). TS positive rate of the high-risk group was much higher than that of the low-risk group[48.72%(19/39)vs10.71%(3/28),P<0.05], as was the case in HRT2 positive rate [15.38%(6/39)vs0%(0/28),P<0.05] or HRT positive rate [89.74%(35/39)vs67.86% (19/28), P<0.05]. However, there wasn't statistic difference in TO between these two groups,neither did TO positive rate(P >0.05).(4) TO and TS were independent of each other whether in the ACS group or in the control group (r value were -0.132 and -0.014,respectively, P >0.05).(5) Logistic univariate analysis showed that HRT2 was the most powerful risk predictor(RR,16.607;95%CI,1.28087.857;P<0.05).The sensitivity,specificity, positive predictive accuracy,negative predictive accuracy,accuracy of HRT2 were 15.38%,100%,100%,45.90%,50.75%,respectively.These figures of TS≤2.5mm/RRI were 48.72%, 89.29%,86.36%,55.56%,65.67%,respectively and it was the fourth powerful risk predict -or(RR,6.437;95%CI,1.661 to 24.939;P<0.05). TO≥0 was a relatively weaker predictor (RR,1.078;95%CI,0.4032.883;P>0.05).(6) Logistic multivariate analysis presented that HRT2(RR,9.216;95%CI,1.052 80.761;P<0.05) and SDNN<70ms(RR,6.492;95%CI,1.613～26.126;P<0.05)were two independent risk predictors. HRT2 was the more powerful risk predictor. Conclusions 1. TS is more sensitive to severe myocardial ischemia, which would lead to decreased or even stunned HRT.. 2. HRT2 is a very potent risk stratifier in ACS patients that is independent of other available risk factors and which is stronger than other predictors in this study. 3. TO and TS were independent of each other, TS has higher prognostic value than TO.
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