According to our research findings, pulmonary infection is one of the risk factors for POAF after VATS treatment for NSCLC. POAF has notable consequences, including prolonged postoperative drainage and hospitalization. To prevent it, administering proactive anti-infective therapy after surgery and implementing physical therapies like percussion, early mobilization, and coughing to clear secretions can effectively reduce pulmonary infections and minimize the incidence of POAF.
The incidence of postoperative atrial fibrillation (POAF) in our study (10.5% %) was greater than reported in the previous studies (3.5–8.6%) [1–4]. Our cohort closely monitored the patients' cardiac function and vital signs within 24–72 hours after the surgery. We detected some potential or transient cases of POAF. Additionally, the patients in our study had a higher age threshold (73 years) than previous[2,3]. These factors may explain the higher incidence of POAF than in other studies.
Preceding studies consistently reported a correlation between POAF and extended hospitalizations (with a median stay of about 13 and 10 days) [2]. Our findings revealed that patients who improved POAF experienced a significantly longer median postoperative hospital stay of 11 days compared to those who did not develop POAF, with a median stay of 9 days (p < 0.05). Furthermore, the group of patients with POAF exhibited significantly longer drainage time and higher drainage volume. To evaluate the potential relationship between platelet counts and drainage volume, we conducted an analysis; however, we found no significant differences between the POAF and non-POAF (n-POAF) groups (p > 0.05).
Previous studies consistently reported that POAF tends to occur within the first three days following surgery [1, 2]. Our study was designed to investigate the timing and incidence of POAF in the postoperative period. Our findings showed that the highest incidence of POAF (51.7%) occurred on the first day after surgery, with 25 out of 29 cases developing within three days post-surgery. This early occurrence of POAF can increase sputum production during the initial 24–72 hours following surgery, leading to acute hypoxia. Factors such as pain and anesthesia directly affect respiration and the cough reflex, further contributing to the incidence of POAF. It is important to emphasize that POAF typically diminishes over time and is often a result of surgical trauma, hypoxia, and other physiological stressors rather than organic heart disease. Therefore, POAF following lung resection is commonly a temporary and transient phenomenon.
Several researchers have suggested amiodarone and digoxin as effective agents for managing POAF [12]. These medications have been demonstrated safety profiles and can be conveniently administered during invasive procedures. In our study, we evaluated their efficacy in treating POAF. Treatment with either amiodarone or digoxin following the onset of POAF resulted in clinical improvement in 26 cases (89.7%) and spontaneous conversion to sinus rhythm in 3 cases (10.3%). Within 24 hours, 22 out of 32 patients (79.3%) reverted to sinus rhythm, while the remaining three patients (9.4%) continued to be experience atrial fibrillation and received regular anticoagulation therapy upon discharge. Symptomatic patients reported sensations of palpitations and chest tightness; however, all patients maintained stable hemodynamic profiles without significant discomfort. It is useful to noting that the medications used in our study effectively improved the clinical condition of most POAF patients, leading to a high rate of spontaneous conversion to sinus rhythm within a short timeframe. Furthermore, the reported symptoms were manageable, with no significant hemodynamic instability or discomfort observed.
In 2002, David Amar conducted a prospective study [13] and found that POAF's incidence increases with age in patients aged 60 or older undergoing open chest surgery. Patients in this age group were considered an independent risk factor for POAF. Subsequent studies have confirmed this conclusion [1,5,9]. In our study, we selected patients with NSCLC who underwent VATS as the study population and set the age cut-off value at 73 years. When patients were over 73 years old, the incidence of POAF was sharply higher than in the non-POAF group (34.5% vs. 18.6%, P = 0.045). However, our multivariate analysis did not identify age as an independent risk factor for POAF, which differs radically from previous research findings [13]. Our analysis suggests that this discrepancy may be linked to the following factors. Firstly, the age cutoff value in our study was 73 years, considerably higher than in previous relevant studies [13], indicating a higher average age in the patient population we studied and potentially introducing an age bias. Secondly, our study focused on patients with NSCLC undergoing VATS, resulting in a relatively homogeneous study population. Therefore, further multicenter prospective studies are needed to explore this issue in-depth.
Thoracoscopy is widely used in practice owing to its minimal invasiveness and faster recovery. As a consequence, the scientific community has been closely examining whether thoracoscopy reduces the incidence of POAF. Numerous studies, including those by Manabu Kashiwagi et al. [1] and Vassili Crispi et al. [11], have indicated that VATS is associated with lower POAF incidence rates compared to open thoracotomy procedures. However, studies such as those by Paulo Veiga Oliveira et al. [14] and Falcoz et al. [15] did not find a significant difference in POAF incidence rates between the two procedures.
In our study, we exclusively analyzed patients who underwent VATS to avoid selection bias, as there were only 8 cases of thoracotomy among the entire population of lung cancer surgery patients. Our separate analysis showed no significant difference in the occurrence of POAF between VATS and thoracotomy surgeries (P = 0.691), consistent with previous studies [14,15]. However, larger studies are needed to validate our findings, as the limited number of cases in the thoracotomy group does not ensure reliable results.
Furthermore, previous studies have reported that the incidence of POAF increases when the surgical duration exceeds 180 minutes [16]. In our study, the cut-off value for surgical duration was also set at 180 minutes, consistent with the mentioned research[16]. Although the final results did not show surgical duration as a significant factor influencing POAF, we still recommend controlling the surgical time and just trying to keep it within 180 minutes whenever possible.
According to existing literature, the extent of lung resection can influence the development of postoperative atrial fibrillation (POAF). Vaporciyan et al. [8] conducted studies that reported a similar incidence of POAF in patients who underwent wedge resection for single lesions and those who underwent multiple wedge resections in the study group. This observation remained consistent even with an increase in lung tissue resection, without a corresponding increase in POAF incidence. Our study shows lung resection was divided into five groups: wedge resection, segmentectomy, lobectomy, bi-lobectomy resection, and pneumonectomy. We found no significant differences in the incidence of POAF among these groups, which is in agreement with the findings of Vaporciyan and colleagues [8]. Another study[3] found that the incidence of POAF in patients who underwent segmentectomy (1.4%) was significantly lower than those who underwent lobectomy (2.8%). However, pneumonectomy significantly increased the incidence of POAF compared to other procedures, notably wedge, segmentectomy, and lobectomy. Crispi et al. [11] reported the incidence rates of POAF after lung surgeries as follows: 3.1% for sublobar resections, 9% for lobectomy, 6% for bi-lobectomy resection, and 11.4% for pneumonectomy. Previous studies [2,11] have established pneumonectomy as a significant independent risk factor for POAF. Several studies [4,9] have suggested a direct correlation between the amount of tissue loss during lung resection surgery, reduced postoperative lung function, inadequate oxygen supply to myocardial tissues, and the potential for causing POAF. Therefore, the extent of lung tissue resection may influence the onset of POAF.
Mediastinal lymph node dissection may influence the incidence of POAF, potentially leading to direct damage to the cardiac plexus at the aortic arch and tracheal bifurcation. Some experts [2, 17] have hypothesized that mediastinal lymph node dissection could trigger atrial fibrillation, increasing the risk of POAF. In a retrospective multivariate analysis involving 593 patients who underwent lung cancer resection, Muranishi et al. [1] found that mediastinal lymph node dissection is an independent risk factor for POAF (OR ND-2/ND-0-1 = 3.06; 95% CI 1.06–10.9, P = 0.0379). However, other studies [18] argue that there is no significant association between them.
Our study conducted separate analyses of the number of mediastinal lymph node stations and the number of nodes cleared during mediastinal lymph node dissection. The median number of cleared mediastinal lymph nodes was 10 in the POAF group and 6 in the n-POAF group. Additionally, the median number of mediastinal lymph node stations cleared was 3 in the POAF and n-POAF groups. These differences between the groups were statistically significant (P < 0.05). However, the results of the multivariate analysis indicated that the number of mediastinal lymph node stations and nodes cleared does not substantially impact POAF, aligning with the findings of previous studies [18].
From an anatomical perspective, an excessive extent of mediastinal lymph node dissection may destroy the cardiac plexus, potentially increasing the occurrence of POAF. Therefore, for patients who do not require mediastinal lymph node dissection, alternative methods such as lymph node sampling or vagal nerve protection could be considered to safeguard the cardiac plexus.
Assessing oxygenation and lung quality in patients before surgery can be done through measures such as pulmonary function tests, blood gas analyses, and the evaluation of red blood cell count and hemoglobin content. In the absence of prior pulmonary function test results, this study utilized blood gas analysis, red blood cell count, and hemoglobin content as indicators. The analysis reveal any significant difference in these measured variables between the two groups (P > 0.05). However, univariate analysis indicated that preoperative hemoglobin content was a potential risk factor (P = 0.048), supported by other studies [1, 5] that identified chronic obstructive pulmonary disease and poor lung function as risk factors for postoperative atrial fibrillation (POAF). Nevertheless, the outcomes of this study are inconclusive, and further data collection and prospective studies are necessary to validate the results.
Local inflammation is widely accepted as a risk factor for POAF, as noted by several scholars [12, 19, 20]. Previous studies have demonstrated a positive correlation between the incidence of POAF and levels of interleukin 2 (IL-2) [21], interleukin 6 (IL-6) [20], and C-reactive protein (CRP) [22]. Boons et al. [19] suggested that prolonged ventilation and postoperative lung infections contribute to POAF in cardiothoracic surgery patients. Hence, implementing preventive measures against postoperative lung infections, such as continuous low-flow oxygen inhalation, may reduce POAF. However, this assertion has taken issue with some scholars [23]. In our study, we found pulmonary infection was the most frequent postoperative complication, accounting for 72.2% (70/97) of all cases, and it was significantly associated with the development of POAF (P < 0.001). Moreover, our data multivariate analysis confirmed that pulmonary infection was an independent risk factor for POAF. Examining postoperative infection markers, including postoperative white blood cells, neutrophil proportion, and CRP, did not reveal any significant differences among them, which is consistent with previous research [23]. Generally, research on blood biomarkers yields inconsistent findings, possibly owing to their unique effects on the heart [24, 25].
The current study consists of two merits. Firstly, prior studies have demonstrated that lung resection can lead to escalated cardiac function, resulting in atrial and bundle branch block, right ventricular dilation, transient pulmonary hypertension, and elevated heart pressure [26]. However, these studies failed to consider the amount of fluid administered during surgery. Thus, excessive hydration during surgery should be avoided to prevent increased cardiac overload, pulmonary edema, augmented sputum production, and postoperative respiratory infections. The study revealed no substantial variations in the net volume of fluid infused between the POAF and n-POAF groups, demonstrating our expertise in fluid management. Nonetheless, further research with a larger sample size is necessary to explore the correlation between net fluid volume infusion and the incidence of POAF. Secondly, electrocardiographic monitoring was routinely conducted on a majority of patients for a minimum of three days to promptly detect any anomalous symptoms. Therefore, the recorded incidence of POAF during hospitalization in the present study is accurate. Another strength of this study lies in the inclusion of patients who underwent VATS for NSCLC. VATS is a well-established surgical approach, and the selection of patients in this study was both focused and comprehensive. Consequently, the results of this study hold clinical significance and offer valuable insights for thoracic surgeons at large.
However, this study had some limitations. Firstly, it was a retrospective study that lacked randomization, making it less controlled, and this had a slight impact on the findings. Secondly, the incomplete data collection on some outcomes, such as pulmonary function and pain, prevented their exploration in this study. Thirdly, the small sample size and limited AF incidence led to defective analysis of the associated risk factors. Lastly, this study found that the stage of NSCLC did not markedly influence the development of POAF. However, it is important to note that our study did not provide further analysis or summary regarding lymph node involvement and tumor size concerning POAF. Therefore, more exploration through multicenter prospective studies is needed.