Effective Factors And Clinical Significance Of Abnormal Deceleration Capacity In Patients With Nonvavular Atrial Fibrillation

Backgrounds Atrial fibrillation（AF）is the most common clinical arrhythmia,with long duration,high morbidity and morbidity,its incidence rising year by year,and the etiology of which is complicated.AF can lead to serious complications,like heart failure,stroke and thromboembolism.Regarding to the treatments of AF,we mainly focused on rhythm control and the prevention of stroke.In rhythm control,radiofrequency ablation has a low success rate and a high recurrence rate.Although the use of anticoagulant drugs can reduce the incidence of stroke,but poor drugs compliance and bleeding risk limits their clinical application.At present,the pathogenesis of AF and stroke prevention and control are still difficulties to overcome in the field of cardiovascular diseases.In addition to the classical electrical remodeling and structural remodeling,studies have found that nerve remodeling caused by cardiac autonomic nerve function changes is closely related to the occurrence and maintenance of AF.Deceleration capacity（DC）is a novel indicator for quantitative assessment of cardiac autonomic nerve function,with advantages of non-invasive,simple and easy to use.It has been shown to be superior to the other traditional indicators,such as left ventricular ejection fraction or heart rate variability.DC was initially used to assess the prognosis of patients with acute myocardial infarction,the lower DC value suggests that the ability of the vagus nerve to modulate the sympathetic nervousness is worse,and the risk of sudden death due to electrical storms and malignant arrhythmias after myocardial infarction is increased.In addition,DC is also used to assess the changes in autonomic nerve function after AF cardioversion,and the effects of different pulmonary venous isolation procedures on cardiac autonomic nerves in patients with AF.But so far,there is no study of nonvalvular AF abnormal neurological dysfunction characteristics and influencing factors,and also lack of DC for the predictive value of ischemic stroke risk in patients with nonvalvular AF.Aims The aim of this study is to investigate the characteristics and influencing factors of autonomic dysfunction in patients with nonvalvular AF and to investigate whether DC can be a new predictor of stroke risk with evaluation of stroke risk scoring system.Methods We collected hospitalized patients with AF in Department of cardiovascular medicine of our hospital from August 1,2015 to June 30,2016.The patients were prescreened according to the inclusion criteria and exclusion criteria of the study.Clinical data were extracted from the electronic medical record system,including demographic data,clinical diagnosis,medical history,electrocardiogram and echocardiography parameters.Extraction of 24-hour Holter electrocardiogram results（effective record duration≥ 20 hours）by using Holter ECG software,and then calculate the DC values.The subjects were divided into DC normal group and DC abnormal group according to the DC values.Clinical baseline data were statistically analyzed,and the characteristics of the two groups were compared.The correlation between the two groups was analyzed by chi-square test and linear regression.The factors with statistical differences were included as variables in binary logistic regression analysis model,and then further explore the independent influencing factors of DC values.The CHADS₂ and CHA₂DS₂-VASc scores of each patient were calculated.By using chi-square test and t-test,the association between DC and ischemic stroke risk score in patients with nonvalvular AF.Results 1.In the present study,we enrolled 785 hospitalized patients with nonvalvular AF（54.0% male,mean age 69.1±11.3 years）;the mean body mass index（BMI）of include patients was 23.6±3.54 kg/m2.The mean DC value was 5.80±2.2ms.Clinical baseline data of these two groups were comparable,with not statistical difference.In echocardiography parameters,right ventricle diameter（23.1±4.2 vs 22.4±3.3,P=0.027）,pulmonary artery inner diameter（23.4±3.4 vs 22.7±3.4,P=0.016）and right atrium diameter（41.8±7.3 vs 40.3±6.3,P=0.007）of normal DC group were larger thanthose in abnormal DC group,the difference was statistically significant.2.Univariate analysis of variables showed that combined with hypertension（P=0.006）,chronic kidney disease（P=0.036）,diabetes mellitus（P=0.028）and previous stroke/TIA（P=0.019）were significantly associated with abnormal DC values;After eliminating these confounding factors above by multivariate regression analysis,hypertension was an independent influencing factor for abnormal DC in patients with nonvalvular AF（OR=1.447,CI:1.014-2.063）.3.Mean CHADS₂ score and-CHA₂DS₂-VASc score of the total subjects was 2.05±1.48 and 3.46±1.90,respectively The results of ANOVA analysis showed that there was significant difference in risk stratification of both CHADS₂ and CHA₂DS₂-VASc scores between normal DC group and abnormal DC group（P=0.004 vs P=0.003）.The results of t test showed that scores of CHADS₂ scoring system in normal DC group were higher than those in abnormal DC group（P=0.001）,and scores of CHA₂DS₂-VASc in DC normal group and DC abnormal group were 1.95±1.47 and 2.35±1.49,respectively,With significant differences（P= 0.001）.Conclusions 1.Hypertension is an independent influencing factor of cardiac autonomic dysfunction in patients with nonvalvular AF.2.Abnomal DC was associated with a higher stroke risk scores in patients with nonvalvular AF.3.DC may serve as a potential novel indicator for ischemic stroke risk prediction in patients with nonvalvular AF.4.Right atrium diameters may be associated with abnormalities DC in nonvalvular AF.However,the further study should be needed.