
==== Front
BMC Pulm Med
BMC Pulm Med
BMC Pulmonary Medicine
1471-2466
BioMed Central London

3231
10.1186/s12890-024-03231-2
Research
Analysis of predictive factors for late recurrence of atrial fibrillation after surgical ablation in patients undergoing rheumatic valve surgery
Wu Qingsong 12
Li Huangwei 2
Xie Linfeng 2
Lin Xinfan 2
Qiu Zhihuang qzhflm@126.com

1
http://orcid.org/0000-0002-9359-4754
Chen Liangwan chenliangwan@tom.com

1
1 grid.411176.4 0000 0004 1758 0478 Department of Cardiovascular Surgery, Union Hospital, Fujian Medical University, Xinquan Road 29, 350001 Fuzhou, Fujian P. R. China
2 https://ror.org/050s6ns64 grid.256112.3 0000 0004 1797 9307 Fujian Medical University, Fuzhou, Fujian P. R. China
20 9 2024
20 9 2024
2024
24 46721 1 2024
19 8 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Objectives

To identify independent predictors of late recurrence of atrial fibrillation (AF) after surgical ablation in patients undergoing rheumatic valve surgery.

Methods

A total of 258 patients who underwent surgical ablation for AF with rheumatic heart disease at our hospital between January 2019 and June 2022 were retrospectively included. The patients were followed up for 12 months. Late recurrence was defined as any AF recurrence longer than 30 s between 3 and 12 months. Patients with or without late recurrence were divided into non-recurrence and recurrence groups. Univariate and multivariate analyses were performed to identify the predictors of late recurrence.

Results

The in-hospital mortality rate was 0.8% (2/258), and the late recurrence rate of AF was 38.4%, including 152 and 95 cases in the non-recurrent and recurrent groups respectively, with a follow-up completion rate of 96.5% (247/256). There were no deaths during follow-up, two patients (0.8%) experienced a stroke, and one patient (0.4%) experienced gastrointestinal hemorrhage. The results of the univariate and multivariate analyses of the preoperative risk factors for late recurrence showed a left atrial (LA) anteroposterior diameter ≥ 52.9 mm (odds ratio [OR] = 2.366, 95% confidence interval [CI] = 1.089–5.138, P = 0.030], ratio of the superoinferior to the anteroposterior diameters of LA (S-AR) < 1.19 (OR = 4.639, 95% CI = 2.181–9.865, P < 0.001), and AF duration ≥ 39 months (OR = 6.152, 95% CI = 2.897–13.061, P < 0.001), and cardiothoracic ratio ≥ 0.63 (OR = 2.716, 95% CI = 1.314–5.612, P = 0.007) were the most significant independent risk factors.

Conclusions

LA anteroposterior diameter ≥ 52.9 mm, S-AR < 1.19, and AF duration ≥ 36 months and cardiothoracic ratio ≥ 0.63 are independent predictors for late recurrence of AF after surgical ablation in patients undergoing rheumatic valve surgery.

Keywords

Rheumatic valve surgery
Atrial fibrillation
Surgical ablation
Late recurrence
Startup Fund for Scientific Research at Fujian Medical University2020QH1076 Key Laboratory of Cardio-Thoracic Surgery (Fujian Medical University), Fujian Province UniversityNo.2019-67 Fujian Provincial Special Reserve Talents LaboratoryNo. 2021-25 issue-copyright-statement© BioMed Central Ltd., part of Springer Nature 2024
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pmcIntroduction

In China, rheumatic heart valve disease continues to be the primary cause of acquired heart valve disease [1, 2]. Atrial fibrillation (AF) is one of the most common complications in patients with rheumatic heart disease (RHD), with an incidence rate of 40–60% [3–5]. AF can lead to left atrial enlargement and structural remodeling, further complicating rheumatic heart valve disease. The resulting impact on hemodynamics increases the likelihood of severe complications, including systemic embolism, thromboembolic stroke, myocardial infarction, and heart failure [3, 6], posing a serious threat to patient safety. In 1987, James L. Cox proposed the traditional cut-and-sew Maze I surgical procedure, them the following iterations were developed thereafter. Besides, the Cox-Maze III remains the gold standard for surgical treatment of AF to this day [7, 8]. However, the advent of ablation tools has significantly simplified the treatment of AF and reduced the complexity of the widely recognized surgical technique [9–11]. Previous studies have shown that preoperative atrial fibrillation reduces the survival of patients undergoing cardiac surgery [12, 13]. While studies have demonstrated that restoration of sinus rhythm can improve the survival rate of patients undergoing cardiac surgery [14, 15]. Multiple studies have also indicated that valve surgery combined with surgical ablation has a good therapeutic effect on improving the prognosis of patients with AF [9, 16–19]. The success and recurrence rates of ablation therapy are influenced by various factors, and treatment failure may be associated with persistent AF, longer AF duration, left atrial remodeling, high CHA2DS2-VASc score, advanced age of female patients during ablation, and concomitant hypertension [20–23].

Unfortunately, despite the initial success of the surgery, a significant proportion of patients experience late AF recurrence. Furthermore, limited literature is available on the predictive factors for late AF recurrence after surgical ablation in patients with rheumatic valve disease. Therefore, this study aimed to explore the independent predictive factors for late AF recurrence in patients with rheumatic valve disease undergoing surgical ablation during valve surgery.

Methods

Ethics approval

The study’s retrospective was approved by the Ethics Committee of Union Hospital of Fujian Medical University(2018JKT031), and conformed to the Declaration of Helsinki. The requirement for informed consent was waived by the Ethics Committee based on the study’s retrospective analysis of patient data.

Study population

We retrospectively included consecutive patients diagnosed with rheumatic valvular disease who underwent valvular surgery and surgical ablation at our institution between January 2019 and June 2022. We included patients diagnosed with rheumatic heart disease accompanied by longstanding persistent AF based on relevant diagnostic criteria [24, 25] and patients meeting clear indications for cardiac valve surgery [26]. The exclusion criteria were as follows: (1) patients with severe ventricular arrhythmia, infective endocarditis, constrictive pericarditis, cardiac cachexia, or malignant tumors, (2) patients undergoing concomitant nonvalvular procedures such as coronary artery bypass grafting, ascending aorta replacement, or congenital heart disease surgery during the operation, (3) patients with a history of recurrent catheter-based radiofrequency ablation, existing cardiac pacemaker implantation, prior cardiac surgery-related pericardial adhesions, or a history of concomitant hyperthyroidism, (4) patients with missing data (more than three items).

Clinical data

The data collected included preoperative baseline clinical characteristics, echocardiography, and 24-hour Holter electrocardiogram results; operative and postoperative data, including transesophageal echocardiography; and follow-up data. Patients were rigorously followed up via our follow-up center office, telephone, WeChat group communication, and outpatient services. All patients underwent either electrocardiographic or 24-hour Holter electrocardiogram and transthoracic echocardiography at 3, 6, and 12 months. The primary endpoint was late AF recurrence. According to whether late AF recurrence occurs, patients are divided into recurrence group and non-recurrence group.

Definition

AF was defined as a single-lead electrocardiogram or standard 12-lead electrocardiogram recording or tracing; heart rhythm remained irregular with no evident repeating P-waves and irregular RR intervals for at least 30 s, excluding atrioventricular conduction impairment [25].

Longstanding persistent AF was defined as continuous AF for > 12 months.

Late AF recurrence was defined as any recurrence of AF longer than 30 s between 3 and 12 months [27].

Successful ablation of AF was defined as the absence of atrial fibrillation, atrial flutter, or any atrial tachycardia lasting > 30 s after discontinuing antiarrhythmic drugs for 3 months. All patients were followed up under the HRS/EHRA/ECA expert Consensus Statement on catheters and surgical ablation of atrial fibrillation [28].

Operational procedure

After successful general anesthesia, a transesophageal echocardiography probe was placed to check for the presence of a thrombus and the shape of the left atrial appendage. All patients underwent a median sternotomy and cardiopulmonary bypass.

During valve heart surgery, surgical ablation was performed simultaneously. AtriCure Bipolar System-Isolator Synergy (Atricure Inc., Westchester, OHU, USA) or MedZenithMZ-RFS-1 (Beijing MedZenith Medical Technology Co., LTD, Beijing, China) was used. The procedure involved the following steps: with parallel cardiopulmonary bypass, the pericardial reflection of the posterior wall of the left and right atria was detached, and the right pulmonary vein atrium was isolated by circular ablation. Through a small incision in the right atrium, ablation is performed on the superior vena cava, inferior vena cava, coronary sinus, and junction of the posterior septum of the tricuspid valve, as well as linear ablation of the right atrial appendage. The Marshall ligament was cut, and circular ablation isolation was performed on the left pulmonary vein atrium. When the body temperature dropped to 34℃, the ascending aorta and superior and inferior vena cava were cross-clamped. Thus opening the interatrial groove, exposing the left atrium, resecting the left atrial appendage, and ablating the left atrial appendage to the left upper pulmonary vein.

Linear ablation of the right and left superior pulmonary veins and right inferior pulmonary vein was performed through an incision between the right superior and right inferior pulmonary veins. This was subsequently intersected with the vestibular ablation line of bilateral pulmonary veins to form the “Box Lesion.” Following this, ablation was performed between the incision and the midpoint of the mitral valve posterior leaflet. Each ablation line was ensured to penetrate the wall 3–5 times, and surgical ablation was completed.

Suppose preoperative esophageal ultrasound indicates a small left atrial thrombus or significant enlargement of the heart, the patients will undergo ablation after cross-clamping of the ascending aorta and cessation of heartbeats. Following this are incisions into the left and right atria for ablation using the same ablation lines as before. The left atrial appendage was excised, sutured, and closed in all patients. Valve surgery was performed sequentially after surgical ablation of AF. After the heart resumed beating postoperatively and full parallel circulation was achieved, extracorporeal circulation was stopped, adequate hemostasis was ensured, and temporary pacing wires were routinely placed on the surface of the heart for backup with an external temporary pacemaker.

Postoperative management

Postoperative antiarrhythmic treatment: When the postoperative heart rate is < 70 beats per minute, the administration of intravenous promethazine injection or temporary pacing may be considered. An intravenous infusion of 450 mg/day of amiodarone was administered when the postoperative heart rate exceeded 70 beats per minute. After removing the endotracheal tube, oral amiodarone hydrochloride tablets were administered at 200 mg three times daily for 3 days. After discontinuing the amiodarone injection, the amiodarone hydrochloride tablet dose was adjusted to 200 mg twice daily for 7 days. Subsequently, the dose was reduced to 200 mg once daily for maintenance, aiming to sustain sinus rhythm for 3–6 months. When AF persisted during the follow-up visit after 6 months, amiodarone hydrochloride tablets were discontinued.

Postoperative anticoagulation treatment: Starting from the first day after surgery, patients received subcutaneous injections of 5000 international units of low-molecular-weight heparin twice daily for anticoagulation. From the second day after surgery, a daily oral dose of 2.5 mg warfarin tablets was administered, and low-molecular-weight heparin was discontinued when the international normalized ratio exceeded 1.5. Patients with mechanical heart valve replacement were prescribed lifelong warfarin, while those with bioprosthetic valve replacement and sinus rhythm required warfarin for 3 months. Continued administration of warfarin or rivaroxaban for anticoagulation was recommended if AF persisted after the follow-up visit.

Statistical analysis

Continuous data are presented as the means ± standard deviation or medians and interquartile range (Q25, Q75), and categorical data are given as the counts (percentage). T-test or U-test used for continuous variables, and chi-square test for categorical variables. The cutoff points were selected based on the receiver operating characteristic curve. After univariate analysis, variables with a P < 0.10 were selected for multivariate logistic regression analysis. All data were analyzed using the IBM SPSS statistical software (version 25.0; IBM Corp., Armonk, NY, USA). Statistical significance was set at P < 0.05.

Results

Clinical data and analysis of factors associated with AF late recurrence

All patients were regularly followed up for 12 months and completed at least two 24-hour Holter electrocardiograms and transthoracic echocardiograms, with a follow-up completion rate of 96.5% (247/256). The recurrence rate of late atrial fibrillation was 38.4%. There were 152 cases in non-recurrent group and 95 cases in recurrent group. During follow-up, there were no deaths; two patients (0.8%) experienced stroke, and one (0.4%) experienced gastrointestinal hemorrhage. The AF duration was significantly longer in the recurrence group than in the non-recurrence group (48.0 [42.0, 66.0] vs. 36.0 [24.0, 60.0] months, P = 0.002). The number of patients with diabetes mellitus was significantly higher in the recurrence group than in the non-recurrence group (28.4% vs. 11.8%, P = 0.002), and the blood glucose level was higher in the recurrence group than in the non-recurrence group (4.92 [4.38, 5.66] vs. 4.72 [4.27, 5.12) mmol/L, P = 0.039). The international normalized ratio in the recurrence group was lower than that in the non-recurrence group (0.99 [0.94, 1.19] vs. 1.06 [0.98, 1.36], P = 0.009). The LA anteroposterior diameters in the recurrence group were significantly larger than those in the non-recurrence group (53.9 [46.8, 57.2] vs. 48.8 [44.2, 52.6] mm, P < 0.001). The S-AR was significantly lower in the recurrence group than in the non-recurrence group (1.16 [1.08, 1.24] vs. 1.30 [1.20, 1.47], P < 0.001). And the cardiothoracic ratio in the non-recurrence group was smaller than that in the recurrence group (0.63 [0.59, 0.66] vs. 0.61 [0.57, 0.63], P = 0.002). (Table 1).

Table 1 Clinical data of participants in the study

Subjects	Total (N = 258)	Group non-recurrent (N = 152)	Group recurrent (N = 95)	P value	
Demographic Characteristics					
 Age (years)	55.0 (51.0, 62.0)	55.0 (51.0, 63.0)	57.0 (49.0, 62.0)	0.281	
 Male gender (n, %)	122 (47.3)	69 (45.4)	48 (50.5)	0.513	
 Body mass index (kg/m2)	22.1 (20.3, 24.8)	21.8 (20.0, 24.9)	22.4 (20.7, 24.7)	0.227	
 Body surface area (m2)	1.6 (1.4, 1.7)	1.5 (1.4, 1.7)	1.6 (1.5, 1.7)	0.291	
 AF duration (months)	42.0 (24.0, 60.0)	36.0 (24.0, 60.0)	48.0 (42.0, 66.0)	0.002	
 Hypertension (n, %)	29 (11.2)	14 (9.2)	15 (15.8)	0.174	
 Coronary heart disease (n, %)	10 (3.9)	6 (3.9)	3 (3.2)	0.747	
 Diabetes mellitus (n, %)	45 (17.4)	18 (11.8)	27 (28.4)	0.002	
 Cerebral infarction (n, %)	12 (4.7)	6 (3.9)	5 (5.3)	0.864	
 Preoperative anticoagulant therapy (n, %)	48 (18.6)	28 (18.4)	19 (20.0)	0.888	
 D-Dimer (ug/mL)	0.67 (0.32,1.99)	0.70 (0.32, 2.13)	0.67 (0.33, 1.10)	0.348	
 Fibrinogen (g/L)	3.22 (2.67, 3.80)	3.25 (2.77, 3.90)	3.00 (2.61, 3.77)	0.236	
 International normalized ratio	1.03 (0.96, 1.23)	1.06 (0.98, 1.36)	0.99 (0.94, 1.19)	0.009	
 Leukocyte (10ˆ9/L)	6.12 (4.97, 7.19)	6.1 (5.1, 7.0)	6.1 (4.7, 7.7)	0.972	
 Heamoglobin (g/L)	136.0 (122.0, 147.0)	135.0 (121.5, 145.0)	136.0 (124.0, 151.0)	0.311	
 Platelet count (10ˆ9/L)	202.0 (164.0, 241.0)	204.0 (160.5, 246.5)	198.0 (168.0, 228.0)	0.288	
 NT-proBNP (pg/L)	786.0 (387.0, 1635.0)	942.0 (389.0, 1697.0)	612.0 (382.5, 1326.0)	0.107	
 Alanine aminotransferase (IU/L)	24.0 (15.0, 38.0)	25.0 (15.0, 39.0)	21.0 (15.0, 34.0)	0.339	
 Aspartate aminotransferase (IU/L)	24.0 (20.0, 33.0)	24.0 (20.0, 33.5)	23.0 (19.5, 31.0)	0.631	
 Serum albumin (g/L)	38.7 (35.8, 41.6)	38.2 (35.7, 40.6)	39.7 (36.7, 41.8)	0.085	
 Serum creatinine (umol/L)	76.0 (65.0, 89.0)	75.0 (66.0, 89.0)	76.0 (63.5, 89.5)	0.972	
 Blood glucose (mmol/L)	4.75 (4.32, 5.42)	4.72 (4.27, 5.12)	4.92 (4.38, 5.66)	0.039	
 Serum cholesterol (mmol/L)	3.94 (3.50, 4.57)	3.91 (3.35, 4.56)	3.96 (3.56, 4.62)	0.436	
 LA thrombus (n, %)	56 (21.7)	28 (18.4)	25 (26.3)	0.190	
 LA anteroposterior diameters (mm)	50.5 (44.9, 54.9)	48.8 (44.2, 52.6)	53.9 (46.8, 57.2)	<0.001	
 LA superoinferior diameters (mm)	63.2 (56.0, 69.9)	63.2 (56.2, 70.1)	62.9 (55.9, 68.3)	0.538	
 S-AR	1.24 (1.13, 1.38)	1.30 (1.20, 1.47)	1.16 (1.08, 1.24)	<0.001	
 Cardiothoracic ratio	0.61 (0.58, 0.65)	0.61 (0.57, 0.63)	0.63 (0.59, 0.66)	0.002	
 Pulmonary artery pressure (mmHg)	38.0 (32.0, 51.0)	37.0 (31.0, 49.0)	39.0 (33.0, 54.0)	0.295	
 Preoperative LVEF (%)	62.7 (56.4, 68.2)	62.5 (56.0, 67.9)	63.0 (57.0, 68.5)	0.219	
 Heart function classification (NYHA )					
  II (n, %)	24 (9.3)	13 (8.6)	9 (9.5)	0.986	
  III (n, %)	172 (66.7)	104 (68.4)	62 (65.2)	0.708	
  IV (n, %)	62 (24.0)	35 (23.0)	24 (25.3)	0.804	
Operative and Postoperative data					
 Mitral valve (n, %)	81 (31.4)	51 (33.6)	25 (26.3)	0.290	
 Aortic valve (n, %)	6 (2.3)	2 (1.3)	4 (4.2)	0.151	
 Multiple valve (n, %)	171 (66.3)	99 (65.1)	66 (69.5)	0.571	
 Mitral valve replacement	202 (78.3)	115 (75.7)	76 (80.0)	0.428	
 Mechanical mitral valve	130 (50.4)	82 (53.9)	48 (50.5)	0.600	
 AtriCure Bipolar System (n, %)	162 (62.8)	94 (61.8)	63 (66.3)	0.565	
 MedZenith (n, %)	96 (37.2)	58 (38.2)	32 (33.7)	0.565	
 Operation time (min)	240.0 (205.0, 270.0)	243.0 (214.0, 276.0)	237.5 (193.0, 260.0)	0.082	
 Cardiopulmonary bypass time (min)	137.0 (114.0, 158.0)	138.0 (119.5, 160.5)	136.5 (106.0, 149.0)	0.122	
 Aortic cross-clamping time (min)	90.0 (74.0, 105.0)	90.0 (77.0, 105.5)	86.5 (67.0, 105.0)	0.125	
 Mechanical ventilation time (hour)	8.0 (6.0, 12.0)	8.0 (5.0, 12.0)	8.0 (6.0, 18.0)	0.111	
 ICU care duration (hour)	2.0 (2.0, 3.0)	2.0 (2.0, 3.0)	2.0 (2.0, 3.0)	0.459	
 Postoperative hospital stay (day)	12.0 (9.0, 14.0)	12.0 (9.0, 14.0)	11.0 (9.0, 14.0)	0.314	
 In-hospital mortality (n, %)	2 (0.8)	1 (0.4)	1 (0.4)	0.736	
 Antiarrhythmic treatment (n, %)	258 (100.0)	152 (100.0)	95 (100.0)	N/A	
 Anticoagulation treatment (n, %)	258 (100.0)	152 (100.0)	95 (100.0)	N/A	
 Pulmonary artery pressure at discharge (mmHg)	30.0 (24.0, 36.0)	30.5 (24.0, 35.0)	28.0 (24.0, 37.0)	0.723	
 LVEF at discharge (%)	64.4 (59.0, 70.7)	64.8 (59.9, 71.2)	63.2 (58.5, 70.0)	0.112	
 Sinus rhythm at discharge (n, %)	205 (79.5)	124 (81.6)	74 (77.9)	0.588	
Continuous data are presented as the means ± standard deviation or medians and interquartile range (Q25, Q75), categorical data are given as the counts (percentage)

AF: Atrial fibrillation

AF: atrial fibrillation, LA: Left atrial, NT-proBNP: N-terminal pro brain natriuretic peptide, S-AR: Ratio of the superoinferior to the anteroposterior diameters of left atrial, LVEF: Left ventricular ejection fraction, NYHA: New York Heart Association, ICU: Intensive care unit

No significant differences were observed in operation time, cardiopulmonary bypass time, aortic occlusion time, bipolar radiofrequency ablation system, and valve operation between the two groups. All surgeries were completed without uncontrolled bleeding or malignant arrhythmias, and patients were safely returned to the intensive care unit for further treatment. Similarly, no significant differences were observed in mechanical ventilation time, intensive care unit duration, and postoperative hospital stay. Additionally, the in-hospital mortality rate showed no difference, standing at 0.8% (2/258) during hospitalization. Two patients died, one due to respiratory failure and the other due to severe infection. During hospitalization, cerebral hemorrhage, cerebral infarction, and gastrointestinal hemorrhage were absent. The non-recurrent group had two cases of grade III atrioventricular block, while the recurrent group had one. The use of temporary pacemakers showed no statistically significant difference, and no cases of malignant arrhythmia or acute heart failure existed in either group. The intra and postoperative data of the two groups are summarized in Table 1.

Predictive efficacy of independent risk factors for AF late recurrence

When the cutoff value of LA anteroposterior diameter was 52.9 mm, the predicted area under the curve (AUC) for late AF recurrence was 0.653 (95% CI = 0.580–0.7250), P < 0.001), with a sensitivity of 56.8% and specificity of 77.0%. When the cutoff value of S-AR was 1.19, the predicted AUC for late AF recurrence was 0.721 (95% CI = 0.655–0.787, P < 0.001), with a sensitivity of 88.4% and specificity of 77.6%. When the cutoff value of AF duration was 39.0 months, the predicted AUC for late AF recurrence was 0.617 (95% CI = 0.544–0.691, P = 0.002), with a sensitivity of 81.1% and specificity of 61.2%. When the cutoff value of the cardiothoracic ratio was 0.63, the predicted AUC for late AF recurrence was 0.616 (95% CI = 0.544–0.687, P = 0.002), and the sensitivity and specificity were 52.6% and 66.4%, respectively. (Fig. 1).

Fig. 1 Receiver operating characteristic curve to assess the ability of predictors of late AF recurrence

Logistic regression analysis of influence on AF late recurrence

Based on the cutoff point determined by the receiver operating characteristic curve, univariate logistic regression analysis showed that LA anteroposterior diameter ≥ 52.9 mm, S-AR < 1.19, cardiothoracic ratio > 0.63, D-dimer ≥ 1.07 ug/mL, AF duration ≥ 39.0 months, ALB < 38.1 g/L, NT-proBNP<737.5 pg/L, preoperative blood glucose > 5.23 mmol/L and diabetes mellitus are independent predictors for AF late recurrence. Multivariate logistic regression analysis showed that LA anteroposterior diameter ≥ 52.9 mm (OR = 2.366, 95% CI = 1.089–5.138, P = 0.030), S-AR < 1.19 (OR = 4.639, 95% CI = 2.181–9.865; P < 0.001), an AF duration ≥ 39 months (OR = 6.152, 95% CI = 2.897–13.061; P < 0.001), and cardiothoracic ratio ≥ 0.63 (OR = 2.716, 95% CI = 1.314–5.612, P = 0.007) were the most significant independent risk factors for AF late recurrence. (Table 2)

Table 2 Univariate and multivariate logistic regression analyses of risk factors for late recurrence of atrial fibrillation

Variable	Univariate Model	Multivariate Model	
OR	95% CI	p-value	OR	95% CI	p-value	
Age ≥ 55 (years)	1.350	0.803–2.270	0.258				
Male sex	0.540	0.320–0.909	0.020	0.947	0.340–2.032	0.173	
Body mass index ≥ 19.7 (kg/m2)	1.479	0.755–2.899	0.254				
Body surface area<1.59 (m2)	0.741	0.441–1.245	0.258				
AF duration ≥ 39.0 (months)	6.743	3.671–12.386	<0.001	6.152	2.897–13.061	<0.001*	
D-dimer ≥ 1.07 (ug/mL)	0.478	0.272–0.840	0.010	0.491	0.231–1.041	0.064	
Fibrinogen<3.05 (mg/dL)	1.404	0.839–2.351	0.197				
International normalized ratio<1.00	1.342	0.499–2.311	0.121				
Heamoglobin ≥ 146.5 (10ˆ9/L)	1.507	0.839–2.707	0.170				
Leukocyte ≥ 6.9 (10ˆ9/L)	1.245	0.724–2.142	0.428				
Platelet count ≥ 214.0 (10ˆ9/L)	0.477	0.277–0.822	0.008	0.527	0.250–1.110	0.092	
NT-proBNP<737.5 (pg/L)	0.480	0.285–0.808	0.006	0.584	0.281–1.216	0.151	
Albumin<38.1(g/L)	2.167	1.267–3.706	0.005	1.910	0.899–4.061	0.092	
Alanine aminotransferase ≥ 21.5 (IU/L)	0.833	0.496–1.398	0.489				
Aspartate aminotransferase ≥ 23.5 (IU/L)	0.736	0.440–1.232	0.244				
Serum creatinine ≥ 78.5 (umol/L)	1.421	0.848–2.382	0.182				
Blood glucose ≥ 5.23 (mmol/L)	1.337	0.760–2.354	0.314				
Serum cholesterol ≥ 3.25 (mmol/L)	1.376	0.731–2.592	0.323				
Hypertension, yes	1.848	0.848–4.027	0.122				
Coronary heart disease, yes	0.793	0.194–3.251	0.748				
Diabetes mellitus, yes	2.956	1.522–5.742	0.001	2.363	0.902–6.196	0.080	
Cerebral infarction, yes	1.151	0.355–3.735	0.815				
Preoperative anticoagulant therapy, yes	1.107	0.579–2.118	0.758				
LA thrombus, yes	0.632	0.342–1.168	0.143				
LA anteroposterior diameters ≥ 52.9 (mm)	4.403	2.529–7.665	<0.001	2.366	1.089–5.138	0.030*	
LA superoinferior diameters ≥ 67.6 (mm)	0.628	0.359–1.097	0.102				
S-AR ≥ 1.19	7.608	4.271–13.551	<0.001	4.639	2.181–9.865	<0.001*	
Cardiothoracic ratio ≥ 0.63	2.200	1.302–3.719	0.003	2.716	1.314–5.612	0.007*	
Pulmonary artery pressure ≥ 38.5 (mmHg)	1.235	0.739–2.063	0.421				
Preoperative LVEF ≥ 61.0 (%)	0.726	0.428–1.231	0.235				
Heart function classification II	1.119	0.459–2.729	0.805				
Heart function classification III	0.867	0.504–1.493	0.607				
Heart function classification IV	1.130	0.622–2.053	0.688				
Mitral valve	0.707	0.401–1.247	0.232				
Aortic valve	3.297	0.592–18.360	0.173				
Multiple valve	1.218	0.703–2.111	0.481				
AtriCure Bipolar System	1.215	0.710–2.078	0.477				
MedZenith	0.823	0.481–1.408	0.477				
Pulmonary artery pressure at discharge ≥ 28.5 (mmHg)	0.780	0.467–1.304	0.344				
LVEF at discharge ≥ 59.8 (%)	1.133	0.649–1.977	0.661				
Sinus rhythm at discharge, yes	0.831	0.442–1.562	0.565				
Those factors p < 0.100 in univariate model were involved in multivariate model

* The difference was statistically significant

OR: odds ratio, CI: confidence interval, AF: atrial fibrillation, NT-proBNP: N-terminal pro brain natriuretic peptide, LA: left atrial, S-AR: ratio of the superoinferior to the anteroposterior diameters of left atrial, LVEF: left ventricular ejection fraction

Discussion

Multiple studies have reported that the low success and high late recurrence rates of AF in patients with RHD pose a genuine challenge for cardiac surgeons [29, 30]. Therefore, a preoperative analysis of risk factors in this patient cohort is essential and meaningful. This guides surgeons in selecting surgical approaches and patient screening, enabling more specific and effective communication with patients and their families before surgery. The 2020 European Society of Cardiology guidelines for the treatment of AF recommend the evaluation of concomitant AF ablation in patients undergoing cardiac surgery. This assessment aims to balance the benefits of freedom from atrial arrhythmias and the risk factors for recurrence, including left atrial enlargement, age, renal insufficiency, and other cardiovascular risk factors [26]. Although numerous predictive factors exist for AF recurrence after surgical ablation, their predictive power is generally weak. Therefore, the decision to undergo surgical ablation should be made after a comprehensive assessment of the potential benefits and risks.

The results of this study indicated that AF duration is a risk factor for late AF recurrence. However, since most patients cannot provide a specific date for the onset of AF, the AF duration can only be estimated based on the duration of symptoms, including heart failure, or the time of initial AF diagnosis. Therefore, the predictive power of AF duration is weak and can only serve as a supplementary predictive indicator. Nevertheless, it is undeniable that the longer the AF duration, the higher the incidence of late AF recurrence. We hypothesized that this may be closely related to the duration of valvular disease in patients. Valvular heart disease leads to remodeling of the atria and ventricles, and AF is often a complication of valvular heart disease, especially left-sided valve lesions. Left atrial pressure, volume overload, or both, caused by aortic or mitral valve disease, can result in structural changes in the left atrium. Chronic atrial enlargement leads to myocardial fibrosis, subsequently affecting atrial electrophysiology and increasing susceptibility to atrial arrhythmias, including AF [31]. Therefore, despite the relatively low success rate of restoring sinus rhythm through surgical ablation in cases of longstanding persistent AF, considering the anatomical correction of heart valve disease, reduction of cardiac load, and timely elimination of pathological causes leading to left atrial enlargement is advisable. These measures can potentially reverse LA remodeling and effectively restore sinus rhythm.

The results of our study also demonstrated that LA anteroposterior diameter and cardiothoracic ratio were independent predictors of late AF recurrence after surgical ablation. LA enlargement has been well recognized to play an important role in the pathogenesis of AF, but the underlying mechanisms are unknown [32]. Atrial enlargement leads to the uneven distribution of atrial fibrosis, but the specific mechanism and distribution characteristics are not clear [33, 34]. Due to the close association between the occurrence of AF in patients with RHD and continuous fibrosis of the valves and enlargement of the left atrium, the therapeutic efficacy of AF ablation in patients with RHD is considered inferior to that of patients undergoing degenerative mitral valve surgery [6, 35, 36]. Some studies have also reported that patients with longstanding persistent AF and mitral valve disease exhibit an uneven distribution of left atrial enlargement and fibrosis [37]. AF is often accompanied by a large LA, indicating a lower success rate and poorer prognosis after surgical or catheter-based treatments. However, because the LA is a geometric cavity, its enlargement involves its size and shape. Recent studies have suggested that changes in LA shape are associated with the onset of AF, as the LA in patients with AF gradually transitions from a normal elliptical shape to a nearly spherical shape [31, 38].

Furthermore, this study indicated that S-AR plays an important role in late AF recurrence, with an S-AR < 1.19 being an independent risk factor for late AF recurrence, having a sensitivity and specificity of 78.6% and 82.1%, respectively. As the S-AR approaches 1, the morphology of the LA tends to become more spherical, transitioning from a normal elliptical to a nearly spherical shape. The size of the LA determines the intraatrial conduction distance. Enlargement of the LA is uneven in both size and shape, leading to disproportionate increases in the distance in different directions within the enlarged LA, which may trigger AF [39, 40]. From a mechanical perspective, a spherical shape is the optimal geometric shape for a cavity to withstand hydrostatic pressure with minimal wall thickness. Therefore, spherical remodeling in response to AF is a natural and logical reaction when the myocardial wall does not exhibit organized active contractions to withstand this adaptation [41]. A recent multicenter left atrial geometry and outcome-AF trial demonstrated that LA sphericity (OR = 1.87, P < 0.05) is an independent risk factor for AF recurrence, which is consistent with our research results [22]. Therefore, appropriate LA volume reduction may be necessary for a larger LA during surgery to restore the LA to an elliptical shape as much as possible, which may have certain benefits in preventing late AF recurrence [42].

Limitation

One limitation of this study is that it included a relatively small number of patients. Second, some asymptomatic recurrences may have been undetected due to the absence of long-term monitoring. Additionally, the follow-up period may not have extended long enough to overlook some very late recurrences (recurrence occurring after 2 years of the ablation procedure). Furthermore, this study lacks comparative research between postoperative follow-up data and preoperative data, which may to some extent affect the comprehensiveness of this study. Therefore, late AF recurrence may be underestimated, and some underlying risk factors may be neglected or less studied.

Conclusion

This study demonstrates that LA anteroposterior diameter of ≥ 52.9 mm, S-AR < 1.19, AF duration ≥ 36 months, and cardiothoracic ratio ≥ 0.63 are independent predictors for AF late recurrence after surgical ablation in patients undergoing rheumatic valve surgery. In clinical practice, the LA anteroposterior diameter, S-AR, AF duration, and cardiothoracic ratio should be considered when assessing patients amenable to AF surgical ablation.

Abbreviations

AF Atrial fibrillation

LA Left atrial

OR Odds ratio

CI Confidence interval

S-AR Ratio of the superoinferior to the anteroposteriordiameters of left atrial

RHD Rheumatic heart disease

LVEF Left ventricular ejection fraction

Acknowledgements

We would like to thank Editage (www.editage.cn) for English language editing.

Author contributions

Liangwan Chen and Zhihuang Qiu designed the study and submitted the manuscript. Qingsong Wu and Huangwei Li prepared the first draft of the manuscript and made the literature review. Qingsong Wu and Huangwei Li are contributed equally to this study and share first authorship. Linfeng Xie and Xinfan Lin made substantial changes in the manuscript. Huangwei Li and Xinfan Lin collected and analyzed data together. All authors read and approved the final manuscript.

Funding

This work was funded by the Key Laboratory of Cardio-Thoracic Surgery (Fujian Medical University), Fujian Province University (No.2019-067) and Fujian Provincial Special Reserve Talents Laboratory (No. 2021-25), and Startup Fund for Scientific Research at Fujian Medical University (2020QH1076).

Data availability

All data generated or analysed during this study are included in this published article.

Declarations

Ethics approval and consent to participate

This study was complied with the principles of the Declaration of Helsinki and approved by Union Hospital Fujian Medical University of the institutional review board (No.XH2023-028). Informed consent was waived in accordance with institutional policy for retrospective studies. All authors read and approved the final manuscript.

Competing interests

The authors declare no competing interests.

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Qingsong Wu and Huangwei Li contributed equally to this study and share first authorship.
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