Assessment of autonomic nerve activity by circadian rhythm at different stages after acute myocardial infarction based on holter data

This project is aimed to perform study concerning the state of autonomic nerve system (ANS) at different stages after acute myocardial infarction (AMI), as well as the comparison with normal controls. The analysis was based on the assessment of circadian rhythm reflected by heart rate variability (HRV). The data were provided by the Telemetric and Holter ECG Warehouse (THEW), among which two databases were extracted. 61 Holter recordings were selected from database AMI (E-HOL-03-0160-001), containing the recordings of two stages for a patient after AMI, one between 24-48 h after AMI (AMI-I) and the other between 5th and 10th day after AMI (predischarge, AMI-II). And 189 Holter recordings were selected from database Normal (E-HOL-03-0202-003) as normal controls. Two episodes in resting state lasting 2 h were selected in each Holter record, one in the period of 7:00~20:00 (day), the other in 0:00~6:00 (night). Non-Gaussianity indexes (λ) with the scale at 100 beats were calculated in each 2 h RR interval series, including the λ of day (λ_d) and night (λ_n), as well as the ratio of them (λ_d/λ_n). Results showed that there were significant differences between λ_d and λ_n for Normal, AMI-I and AMI-II. For λ_d/λ_n, there were significant differences between Normal (0.57(0.42-0.81)) and AMI-I as well as AMI-I (0.80(0.57-1.18)) and AMI-II (0.60(0.45-0.79)), but not between Normal and AMI-II. The results suggest the loss of Circadian Rhythm at AMI-I and the regain of it at AMI-II. Since the loss of circadian rhythm is revealed to be a typical symbol of autonomic dysfunction, further monitoring and assessment of circadian rhythm is necessary for post-AMI patients.