The Clinical Value Of Heart Rate Turbulence In Patients With Acute Coronary Syndrome

Objective:With the development of economy and people's lifestyle change, cardiovascular disease, especially coronary heart disease, has become a leading cause of death among people. As a serious kind of coronary heart disease, acute coronary syndrome (ACS) is mainly due to unstable coronary atherosclerotic plaque,inflammation induced platelet aggregation, finally, caused myocardial cells ischemia and necrosis. It is commonly accompanied by unpredictable ventricular tachvcardia (VT),ventricular fibrillation,heart failure, even, sudden cardiac death. Even if has opened the vascular to recovery myocardial reperfusion by thrombolysis or percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG), it still has a state of high mortality and mutilation rate. Now, there is a ineffective index to assess high-risk patients with ACS. So, more and more doctors begin to pay close attention to how to predict and prognosis of ACS. Numerous researches have suggested that heart rate turbulence (HRT) can reflect the cardiac autonomic function. The balance of cardiac autonomic function depends on interaction by sympathetic nerve and parasympathetic nerve. Vagus nerve can anti arrhythmic, if there is a disorder of autonomic function, the risk of malignant arrhythmia will be increased. We can give drug and implantable cardioverter defibrillator (ICD) to high-risk patients which can effectively reduce malignant arrhythmia and sudden cardiac death (SCD), by observed the HRT in patients with ACS. The aim of this study is the following:provide a reliable index for doctor to ACS risk stratification and evaluate prognosis.Methods:We selected 282 examples in Tianjin Chest hospital in October 2008 to September 2009 continuously. All examples were divided into two groups:Control group (n=70) with healthy and ACS group (n=212) with patients in ACS. All the subjects were performed 24-hour Holter during the period from 1 to 3 days in hospital. According the Holter records to measure and calculate the parameters of HRT: turbulence onset (TO) and turbulence slope (TS); and the parameters of heart rate variability (HRV):24 hours standard deviation of NN intervals (SDNN). We obtain clinical information (age,gender hypertension,diabetes,smoking),left ventricular ejection fraction (LVEF) and coronary angiography(CAG). The patients with ACS were divided into acute myocardial infarction (AMI) group and unable angina pectoris (UAP) group according to cardiac enzymes and electrocardiogram. Observe the difference of HRT between ACS group and control group and two subgroups in ACS. All of patients were followed up (20.5±12.2) months. Recording the major adverse cardiac events (MACE), the patients with ACS were divided into MACE group and non MACE group, compared the difference of HRT between MACE group and non MACE group, find the value of HRT in evaluate prognosis by Logistic regression anaysis, and the relation of HRT to coronary lesion and left ventricular systolic function by Pearson correlation analysis.Results:(1)TO in ACS group was significantly higher than control group(P<0.01), and TS, LVEF and SDNN in ACS group was significantly lower than control group (P<0.01, P<0.05); There were significantly differences in TS and LVEF between AMI group and UAP group (P<0.01), but there were differences in SDNN and between two groups (P>0.05). (2) Compared with non MACE group, the HRT and LVEF in MACE group were much significant (P<0.01); the SDNN in MACE group were no significant (P>0.05); The rate of abnormal HRT in MACE group (90.9%) was higher than non MACE group (76.8%), but there is no significant difference in two groups. The HRT and LVEF were closely related to MACE attack which was detected by Logistic regression analysis. (3) Pearson correlation analysis show TO was positively correlated with coronary lesions (r=0.19,P=0.01), TS was negatively correlated with coronary lesions (r=-0.29, P=0.00); while TO was negatively correlated with LVEF (r=-0.16, P=0.02), TS was positively correlated with LVEF (r=0.17,P=0.01).Conclusions:HRT is significantly blunted and cardiac autonomic function is declines in patients with ACS; HRT can identify high-risk patients and provide a index to evaluate prognosis; it is sensitive to cardial blood perfusion and left ventricular ejection fraction, So HRT can reflect coronary lesion and left ventricular systolic function.