Correlation Between Decreased Autonomic Nervous System Activity And Postoperative Atrial Fibrillation After Coronary Artery Bypass Grafting

Objective : To study the relationship between heart rate variability(HRV)and postoperative atrial fibrillation(POAF)after coronary artery bypass grafting(CABG),and then explore the mechanism of POAF.Methods : This study is based on a single-center retrospective study,which continuously enrolled 858 patients who underwent CABG in the Northern Theater General Hospital from December 2020 to June 2022,including 628 males and 230 females,with an age range of 54～71 years.The standard deviation of normal sinus intervals(SDNN),root mean square values(RMSSD)for differences between adjacent NN,percentage of consecutive NN interval differences of more than 50 ms(PNN50),changes in high-frequency power(HF),low-frequency power(LF),and low-frequency to high-frequency ratio(LF/HF)were compared.Patients were divided into two groups,non-POAF(225cases)and POAF(633cases),and multivariate logistics regression analysis was used to explore factors that may have an impact on the occurrence of POAF.Results:1.Compared with CABG before surgery,the standard deviation of normal sinus interval(SDNN),root mean square value(RMSSD)of adjacent NN interval differences,percentage of continuous NN interval difference of more than 50 ms(PNN50),high frequency power(HF),low frequency power(LF)and ratio of low frequency to high frequency(LF/HF)of postoperative HRV were significantly reduced(P <0.05);2.There were significant statistical differences in age,ejection fraction(EF),short-axis shortening rate(FS),left atrial diameter(LAD),intensive care unit time,ventilator time,and congestive heart failure between POAF and non-POAF(P<0,05);The postoperative change of Lg(ΔLF/HF)in HRV was greater than that before surgery(P<0.05),and the difference was statistically significant.3.The results of POAF regression analysis showed that age [OR,95% CI: 1.06(1.03,1.08)] and LAD [OR,95% CI: 1.07(1.03,1.13)] in model 1 increased the risk of POAF,and Lg(preoperative HF-postoperative HF)[OR,95% CI: 0.74(0.64,0.85)]could reduce the risk of POAF;Age in model 2 [OR,95% CI: 1.06(1.04,1.09)],LAD [OR,95% CI: 1.08(1.03,1.13)],and Lg(preoperative LF/HF-postoperative LF/HF)[OR,95% CI: 1.13(1,1.26)] all increased the risk of POAF.Conclusion : Postoperative SDNN,RMSSD,PNN50,HF,LF,LF/HF were significantly lower than before surgery,and the reduction of postoperative HF may be an independent protective factor for POAF,while the reduction of postoperative LF/HF may be an independent risk factor for POAF.POAF may be caused by homeostatic imbalance of sympathetic and parasympathetic nerves after CABG surgery.