The Clinical Investigation Of Heart Rate Variability And Its Circadian In Acute Coronary Syndrome

Objectives: To observe the heart rate variability(HRV) and its cireadian as assessed by 24-h ambulatory electrocardiographic recording in patients with acute coronary syndrome(ACS), stable angina pectoris(SAP) and normal subjects, to study the change of HRV in ACS and its relation to the severity of coronary artery disease.Methods: The study population consisted of three groups: 22 ACSpatients, 22 stable angina pectoris patients and 20 normal subjects. HRV was evaluated by using 24-hour Holter monitoring in all subjects. The ECG recording were divided into day-time(08:00-22:00) and night-time(22:00-08:00), and a circadian rhythm analysis was performed. Coronary artery angiography were performed in patients groups, difference of the narrow severity, pathological change limits were analysis to calculated the narrow severity score.Results: There was a significant decline of 24-hour values of all HRV parameters in ACS relative to stable angina pectoris patients and controls, with the highest in controls, the lowest in ACS, and intermediate value in stable angina. SDNN, SDANN had significantly difference among these three groups(P<0.05). rMSSD and PNN50 had significantly difference only between ACS and controls(P=0.003 and P=0.002, respectively). All parameters except SDANN revealed a marked day-night pattern in normal subjects, with a peak at nighttime and a plateau at daytime, but circadian rhythms of SDNNi, rMSSDand PNN50 absented in ACS. All time domain parameters of HRV negatively correlated with narrow severity score. SDNN > SDANN and rMSSD had significantly correlate with the narrow severity score( P<0.01), meanwhile SDNNi and PNN50 had such a tendency, but did not show significant difference(P=0.093 and P=0.086, respectively).Conclusions: Compared to the normal controls, time-domain HRV parameters are decreased significantly in ACS, and its circadian rhythm absented. The decreased magnitude of HRV is related to the severity of coronary artery disease. HRV could be utilized quantitatively to reflect the severity of CAD.