1.1 Patients
Patients with AF who underwent non-cardiac surgery under general anesthesia from May 2019 to May 2020 were included in this study. Ethical approval was obtained from the Ethics Committee of The First Affiliated Hospital of University of Science and Technology of China (USTC, China).
Inclusion criteria were as follows: (1) Patients’ age ≥ 60 years old; (2) Patients with history of elective non-cardiac surgery; (3) Patients who were diagnosed as permanent atrial fibrillation; (4) No cognitive impairment, no hearing impairment, no mental and neurological disorders.
Exclusion criteria were as follows: (1) Those requiring second surgery; (2) Patients who were allergic to the anesthetic drugs that should be used.
1.2 Methods
1.2.1 Preoperative test
Routine inspection: All patients underwent routine preoperative tests and cardiac evaluation, including dynamic electrocardiogram, chest X-ray, echocardiography, and laboratory examinations. Clinical assessment was performed by the same anesthesiologist preoperatively.
Patients’ basic demographic characteristics were as follows: age, gender, body mass index (BMI).
Anticoagulation: It was attempted to indicate the necessity of performing anticoagulant treatment, the significance of utilization of other drugs preoperatively, left ventricular ejection fraction (LVEF), and applying CHADS2 score for risk stratification for thrombotic events.
Cardiac ejection fraction, mean ventricular rate, high/medium risk of surgery, Goldman's cardiac risk index, New York Heart Association (NYHA) classification score, and American Society of Anesthesiologists (ASA) physical status score. According to the 2007 American College of Cardiology/American Heart Association (ACC/AHA) guidelines, non-cardiac surgery with high-risk and medium-risk was defined, and low-risk non-cardiac surgery included endoscopy, biopsy, cataract surgery, and breast surgery. High-risk non-cardiac surgery involved the operation of massive blood loss in vascular surgery, or the operation that takes longer than 3 h [9].
1.2.2 Intraoperative test
Intraoperative monitoring included invasive arterial blood pressure, 5-lead electrocardiogram, pulse oxygen saturation, and partial pressure of carbon dioxide. The recorded data included grade of stainless steel used in surgery, name of surgery, type of anesthesia, duration of surgery.
Anesthetic satisfaction score was calculated with respect to existence of tachycardia during surgery, hypotension requiring booster maintenance, hypoxemia, hypothermia or hyperthermia, delayed resuscitation, the Richmond Agitation-Sedation Scale (RASS) after waking up, and utilization of analgesia pump. Tachycardia was defined as a ventricular rate greater than 100 beats/min, and hypoxemia was presented as arterial partial pressure of oxygen < 60 mmHg, or oxygen saturation < 90%, lasting for more than 5 min. Hypothermia was defined as body temperature < 36 ℃, hyperthermia as body temperature > 37.5 ℃, and delay in recovery as the time taken from complete cessation in anesthetic agent use was recorded as postanesthetic recovery time: patient is fully awake (regain consciousness and handshake); patient can move all 4 extremities voluntarily or on command; patient can freely perform deep breathing and can cough freely [10] (Table 6).
1.2.3 Follow up and grouping
QoR-15 scale was scored at 24 h preoperatively and at 24, 72, and 120 h postoperatively; additionally, the patient was followed-up by telephone at 30 days after surgery to indicate whether there were cardiovascular and cerebrovascular complications (cardiac failure and stroke). The patients were divided into two groups according to the score of QoR-15 at 120 h after surgery, which included 122-150 points (satisfactory recovery, group A) and 0-121 points (poor recovery, group B) [11].
1.2.4 Laboratory test
Blood sample (2 ml) was collected in the 1st day before and after surgery to monitor the concentrations of BNP, hs-cTn, and soluble presepsin. Blood was collected in 5-ml EDTA tubes and kept on ice no longer than 5 min before centrifugation at 3000 rpm for 15 min at 4 ℃. Plasma was added into polypropylene tubes and stored at -80 ℃ for subsequent analysis. The above-mentioned indicators were measured by the double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) [BNP (NO20060514H), hs-cTn (NO20060509H), and presepsin (NO20060507H) were provided by Jiangsu Meimian Industrial Co., Ltd., Zhangjiagang, China]. The normal range of the these reagents was defined as follows: BNP (278.5-685.5 pg/ml), hs-cTn (688.42-1285.5 pg/ml), and (presepsin: 6.45-15.5 ng/ml).
1.3 Statistical analysis
Sample size: The events per variable (EVP) method was employed to calculate the sample size in the current study, that is the number of events for each independent variable, where events represent the category with a small number of dependent variables, EPV=10, to ensure accurate results[12]. It was confirmed that 120 cases reached the required sample size.
Statistical analysis was performed using SPSS 20.0 software (IBM, Armonk, NY, USA). Quantitative variables with normal distribution were presented as mean ± standard deviation (SD) and analyzed using the Student’s t-test, and the Wilcoxon rank-sum test was employed to analyze abnormally distributed variables. The chi-square test was used to compare count data. P<0.05 was considered statistically significant. Univariate logistic regression analysis was utilized for significantly correlated variables, and independent risk factors were identified at P < 0.05.