Arrhythmia Following Congenital Heart Disease Surgery in Oman: Incidence and risk factors – A prospective study

TL;DR

A study in Oman found that 14.2% of children who had heart surgery developed arrhythmias, with junctional ectopic tachycardia being the most common type.

Contribution

The study identifies prolonged cardiopulmonary bypass time and prior cardiac surgery as independent risk factors for postoperative arrhythmias in children with congenital heart disease.

Findings

Junctional ectopic tachycardia was the most frequent arrhythmia (57.1%) following congenital heart disease surgery.

Prolonged cardiopulmonary bypass time and a history of previous cardiac surgery were independent predictors of postoperative arrhythmias.

Arrhythmia patterns were found to be specific to the type of heart defect and surgical procedure.

Abstract

This study aimed to determine the incidence, outcomes and risk factors of arrhythmia in children undergoing congenital heart disease (CHD) surgery in Oman.

This prospective cohort study was conducted between 2023 and 2024 at the National Heart Centre, Muscat, Oman. Paediatric patients who underwent CHD surgery were included; those with preoperative arrhythmia or permanent pacemakers were excluded. Demographic, intraoperative and postoperative variables were collected. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of postoperative arrhythmia.

A total of 346 patients were included in this study, of which 49 (14.2%, 95% confidence interval: 10.6–18.3%) developed postoperative arrhythmias. Junctional ectopic tachycardia (JET) was most frequent (57.1%), followed by atrioventricular block (20.4%) and supraventricular tachycardia (18.4%); 3 patients with complete heart block required permanent pacemaker implantation and 1 patient died after ventricular tachycardia. Patients with arrhythmia had significantly longer cardiopulmonary bypass (CPB; P = 0.005) and cross-clamp times (P = 0.040). On multivariate analysis, prolonged CPB time (P = 0.049) and a history of previous cardiac surgery (P = 0.041) were independent predictors. Arrhythmia patterns were lesion-specific: (1) JET after tetralogy of Fallot, atrioventricular septal defect (AVSD) and arterial switch repairs; (2) complete heart block after AVSD or inlet VSD repairs; and (3) atrial arrhythmias after atrial-level procedures.

Postoperative arrhythmias occurred in 14.2% of children after CHD surgery in Oman, with JET being the most common. Prolonged CPB duration and prior cardiac surgery independently predicted arrhythmia, emphasising the need for vigilant monitoring and targeted perioperative management in high-risk groups.

Tables

Table 1.. Characteristics of included patients (N = 346).

Characteristic	n (%)
Age group
Neonate (≤1 month)	45 (13)
Infant (1 month to ≤12 months)	141 (40.8)
Toddler (12 months to ≤ 24 months)	46 (13.3)
Early childhood (24 months to ≤ 60 months)	56 (16.2)
Middle childhood (60 months to ≤ 132 months)	51 (14.7)
Late childhood (132 months to ≤ 216 months)	7 (2)
Sex
Male	183 (52.9)
Female	163 (47.1)
Nationality
Omani	325 (93.9)
Non-Omani	21 (6.1)
History of previous surgery
Yes	71 (20.5)
No	275 (79.5)
Median weight in kg (range)	7.1 (2–46)
Mean cardiopulmonary bypass time in min ± SD	138.05 ± 72.55
Mean aortic cross-clamp time in min ± SD	90.60 ± 54.84
Need for ECMO post-operation
Yes	8 (2.3)
No	338 (97.7)
Arrhythmia
Yes	49 (14.2)
No	297 (85.8)

Table 2.. Arrhythmias in the study's cohort.

Postoperative arrhythmia (n = 49)	n (%)
Junctional ectopic tachycardia	28 (57.1)
Atrioventricular block	10 (20.4)
Supraventricular tachycardia	9 (18.4)
Ventricular tachycardia	2 (4.1)
Time of arrhythmia (n = 49)
In operation theatre	18 (36.7)
First 12 hours	24 (49)
>24 hours	3 (6.1)
>72 hours	4 (8.2)
Outcome of arrhythmia
Resolved	45 (91.9)
Permanent (required pacemaker implantation)	3 (6.1)
Death	1 (2)

Table 3.. Detailed breakdown of arrythmias by age group.

Age group	Arrhythmia	Non-arrhythmia	% with arrhythmia
Neonate (≤1 month)	6	39	13.3
Infant (1 month to ≤12 months)	21	120	14.9
Toddler (12 months to ≤ 24 months)	13	33	28.3
Early childhood (24 months to ≤ 60 months)	3	53	5.4
Middle childhood (60 months to ≤ 132 months)	5	46	9.8
Late childhood (132 months to ≤ 216 months)	1	6	14.3

Table 4.. Univariable and multivariable analysis of risk factors for postoperative arrhythmia.

	n (%)
Variable	Arrhythmia (n = 49)	Non-arrhythmia (n = 297)	Univariable test	P value	Adjusted OR (95% CI)	Multivariable P *
Sex (male)	30 (16.4)	153 (83.6)	Fisher's exact test	0.220	1.34 (0.65–2.76)	0.431
Previous surgery	12 (16.9)	59 (83.1)	Fishers Exact test	0.499	2.51 (1.04–6.07)	0.041
Age group	See below	See below	Chi-Square	0.035	0.75 (0.60–0.95)	0.020
Mean weight on admission in kg ± SD	8.2 ± 5.3	9.5 ± 6.9	t-test	0.142	0.94 (0.78–1.13)	0.488
Mean cross clamp time in min ± SD	109.2 ± 68.7	86.8 ± 50.9	t-test	0.040	1.20 (1.05–1.50)	0.030
Mean bypass time in min ± SD	165.26 ± 80.46	132.9 ± 69.9	t-test	0.005	1.004 (1.000–1.008)	0.049
ECMO post-operation	0 (0)	8 (100)	Fischer's exact	0.610	–	–

Full text

1. Introduction

Congenital heart disease (CHD) is the most common congenital anomaly, affecting approximately 1% of live births globally.^1^ Advances in surgical techniques and perioperative care have significantly improved survival rates; however, the incidence of postoperative complications, including arrhythmias, remains a critical concern.

Arrhythmias following CHD surgery can vary from benign transient conditions to life-threatening arrhythmias that require urgent intervention. These complications may result from surgical manipulation, myocardial ischaemia, electrolyte imbalances or pre-existing cardiac abnormalities.^2^ According to the literature, the incidence of arrhythmias post-CHD surgery is reported to be between 7.5% and 48%.^3^ Understanding the local incidence and contributing risk factors is crucial for enhancing clinical outcomes.

Arrhythmias in the postoperative period can arise from various patient-related and surgery-associated factors. Patient-specific risk factors include the inherent complexity and nature of the CHD, while surgical risk factors encompass myocardial injury, placement of sutures near the conduction pathways, electrolyte imbalances, inflammatory responses triggered by cardiopulmonary bypass (CPB), residual haemodynamic disturbances and the arrhythmogenic effects of medications commonly administered during the postoperative phase.^45^ Certain congenital heart diseases are reported to be associated with specific arrhythmias postoperatively. Lesions such as tetralogy of Fallot (TOF) and atrioventricular septal defects (AVSD) are prone to junctional ectopic tachycardia (JET) or complete heart block (CHB), while atrial-level repairs such as Fontan or partial anomalous pulmonary venous drainage (PAPVD) repair procedures predispose to supraventricular arrhythmias.^24^ Recognising lesion-specific arrhythmia patterns is essential for risk stratification, perioperative management and long-term follow-up.

In Oman, the burden of CHD and its surgical outcomes remains underexplored, with limited data available on the incidence and management of postoperative arrhythmias.^6^ This knowledge gap underscores the need for comprehensive research to identify patterns and predictors specific to the Omani population. Healthcare providers can develop targeted strategies to improve patient outcomes and optimise resource allocation by addressing these gaps.

This study aimed to elucidate the incidence of postoperative arrhythmias and identify the key risk factors associated with these complications among patients undergoing CHD surgeries in Oman. The findings provide valuable insights for clinicians and policymakers, ultimately contributing to enhanced care for this vulnerable population.

2. Methods

This prospective study was conducted between May 2023 and May 2024 at the National Heart Centre in Muscat, Oman; it is the only centre in the country where patients with CHD are operated on. All paediatric patients with congenital heart disease who underwent surgical repair or palliation during the study period were included. Patients with a known history of arrhythmias, those with a pre-existing permanent pacemaker and those who underwent isolated catheter-based palliation were excluded.

Data were collected from the Hospital Information System. Collected data were divided into 3 phases: pre-operative, intra-operative and postoperative. Preoperative variables included demographic information (age, sex and nationality), anthropometric measurements (weight and height), history of previous cardiac surgery and the type of CHD. Intraoperative variables encompassed the type of surgery performed, duration of surgery, CPB time, aortic cross-clamp time and hypothermia. Postoperative data focused on developing and managing arrhythmia and the length of hospital and intensive care unit stay.

All patients postoperatively were connected to continuous cardiac monitoring; those who developed arrhythmia had an electrocardiogram (ECG) documented and reviewed by a consultant electrophysiologist to confirm the diagnosis. All patients had pre-discharge ECGs documented and follow-up appointments were reviewed for the development of late-onset arrhythmia.

Statistical Package for Social Sciences (SPSS) software, Version 26 (IBM Corp., Armonk, New York, USA) was used for data analysis. For descriptive purposes, categorical variables were described as frequencies and percentages. Continuous variables were presented as mean with standard deviation or median with interquartile range (25^th^–75^th^). The incidence was presented as a percentage with a 95% confidence interval (CI). To assess association between variables, univariate analysis were performed using Chi-square, Student t-test and Mann-Whitney U test according to the nature and distribution of the data. Odds ratios (OR) were calculated where applicable. Variables with a P value <0.10 in univariate analysis were included in a multivariate logistic regression model to identify independent risk factors. A P value of <0.05 was considered significant.

3. Results

A total of 360 patients underwent open heart surgery for CHD at the National Heart Centre in Oman during the study period. Of these, 346 fulfilled the inclusion criteria (the remainder had a permanent pacemaker and came for battery replacement or had arrhythmia at the time of diagnosis). Out of the 346 patients, 52.9% were males and 47.1% were females. The vast majority were infants aged between 1 month and 12 months (40.8%). Most patients had no previous cardiac surgery history (79.5%). The median weight on admission was 7.1 kg (2–46). A total of 319 patients underwent cardiac surgeries under CPB. For the intra-operative variables, the median cross clamp time was 81 minutes (47.2–120), the median bypass time was 129 minutes (85–168) and the median temperature was 32°C (28–33) [Table 1].

The overall incidence of postoperative arrhythmia was 14.2% (95% CI: 10.6–18.3%, n = 49). JET was the most common type of arrhythmia observed in 28 patients (57.1%), followed by atrioventricular block reported in 10 patients (20.4%) then supraventricular tachycardia (SVT) in 9 patients (18.4%); 2 patients developed ventricular tachycardia (VT) (4.1%), and 1 of them died during resuscitation. Out of the 10 patients with atrioventricular block, 3 developed CHB requiring implantation of a permanent pacemaker [Table 2].

Patients in the study were divided into 2 groups: those with arrhythmia and those without [Table 3]. In the univariable analysis, patients who developed arrhythmia had longer CPB times (165.3 ± 80.5 minutes versus 132.9 ± 69.9 minutes; P = 0.005) and longer cross-clamp times (109.2 ± 68.7 minutes versus 86.8 ± 50.9 minutes; P = 0.040). Age group differences were also significant on univariable testing (likelihood ratio P = 0.035). Sex, prior surgery and extracorporeal membrane oxygenation (ECMO) were not significantly different by univariable testing [Table 4].

On multivariable logistic regression, longer CPB time and previous cardiac surgery were independently associated with postoperative arrhythmia after adjusting for age, weight and sex. Each additional minute of CPB was associated with a small increase in odds of arrhythmia (adjusted OR = 1.004 per minute, 95% CI: 1.000–1.008; P = 0.049), equivalent to an adjusted OR of ~1.13 per 30 minutes of CPB. A history of previous cardiac surgery was associated with higher adjusted odds of arrhythmia (adjusted OR = 2.51, 95% CI: 1.04–6.07; P = 0.041) [Table 4]. The final model showed modest discrimination (AUROC 0.65) with no evidence of poor calibration (Hosmer-Lemeshow P = 0.54).

4. Discussion

This study provided valuable insights into the incidence and risk factors of postoperative arrhythmias following CHD surgeries in paediatric patients in Oman. The findings demonstrate that arrhythmias occurred in 14.2% of the patients within the early postoperative period, with JET being the most prevalent arrhythmia (57.1%), followed by atrioventricular block (20.4%) and SVT (18.4%). While a small number of patients (2.1%) developed life-threatening arrhythmias such as VT, most of the arrhythmias were transient and resolved with supportive care. The patient who died after an episode of VT was diagnosed with single ventricle physiology, pulmonary atresia, hypoplastic tricuspid valve, hypoplastic right ventricle and intact septum. He underwent atrial septectomy, Left Pulmonary Artery-plasty, and right modified Blalock-Taussig (BT) shunt. He developed sepsis postoperatively and had multi-organ failure. On postoperative day 8, he developed VT for which he required electrical cardioversion. He was found to have high potassium and was resuscitated but eventually developed cardiac arrest and was not revived.

In the current study, permanent pacemaker implantation were necessary for 3 patients (6.1% of the arrhythmia cohort) with persistent CHB, indicating the significant clinical implications of postoperative arrhythmias in this cohort.

The arrhythmia incidence of 14.2% falls within the range reported in the literature, which spans 7.5–48%.^7^ A retrospective study done in 2020 in Saudi Arabia by Alotaibi et al. illustrated an incidence of 17% of arrhythmia post-cardiac surgery, with the most common one being JET, followed by CHB and SVT. They showed that long bypass, cross-clamp time and electrolyte abnormalities were risk factors.^8^ Another study published in 2022, which was carried out in Pakistan by Ishaque et al., showed an incidence of 22.8% arrhythmia after repair of congenital heart disease.^5^ Similar to the previous study, the most common was JET, followed by CHB. Also, prolonged CPB time was a risk factor.^5^ Delaney et al. carried out a similar but prospective study at Yale's New Haven Hospital in the USA.^9^ It showed that arrhythmias occurred in 15% of the total population of patients undergoing open heart surgery; JET was the most common one. The younger the patient, the more the bypass and cross-clamp times were associated with a higher incidence of arrhythmias.^9^ In 2007, another prospective study published by Rekawek et al. reported the incidence of arrhythmia at 14%.^10^ JET was the most common, followed by SVT. Young age, lower weight and longer bypass time were reported as risk factors.^10^ On the other hand, a study done in Cameron by Chelo et al. showed an incidence of 31.3%.^11^ This represents the incidence in children postoperation for both congenital and acquired heart diseases. The most common one was SVT. They demonstrated that low weight at surgery was a significant risk factor for developing an arrhythmia.^11^ This variability could be attributed to differences in study populations, surgical techniques and postoperative care protocols. The current study adds a critical layer of information by focusing on a cohort in Oman, a country with a unique healthcare setting and demographic characteristics, where data on paediatric postoperative arrhythmias remain scarce.

A notable finding of this study was the association between prolonged CPB time and a history of previous cardiac surgery as independent risk factors for the development of arrhythmias. This supports previous studies indicating that prolonged surgical times are associated with myocardial injury, electrolyte imbalances and inflammatory responses, all of which can contribute to the development of arrhythmias.^89^ This study's data reinforces the importance of optimising surgical and bypass techniques to reduce the duration of these processes, which may, in turn, mitigate the risk of arrhythmias.

Younger age and lower weight were associated with arrhythmias in univariate analysis, but were not independent predictors in multivariable modelling. Infants and small-for-weight children are more likely to develop arrhythmias, which could be due to the relative immaturity of their cardiac conduction system, as well as their higher metabolic demands and smaller myocardial mass.^12^ These findings are consistent with existing literature, which emphasises that younger paediatric patients are at higher risk for arrhythmias following CHD surgery due to their underdeveloped cardiac structures.^13^

History of previous cardiac surgery emerged as an independent risk factor in multivariable analysis. This association could be explained by the fact that those patients have a higher burden of scarring and conduction disturbance, which increases arrhythmia risk. It is crucial to consider these factors when planning the surgical approach for such high-risk groups.

Interestingly, no significant differences were found between patients with and without arrhythmias in terms of sex, ECMO requirement and hypothermic temperatures used during surgery. This suggests that while these factors may be important in some settings, they do not appear to impact the incidence of arrhythmias in the current cohort substantially. This finding could reflect differences in clinical practices or patient populations across studies. The lack of association with sex is particularly notable, as some previous studies have suggested a higher incidence of arrhythmias in male patients.^589^ However, in the current study, sex did not show a significant impact, indicating that the risk factors for arrhythmias may be more influenced by the nature of the surgical procedure and the patient's physiological characteristics than by sex. The lack of association with ECMO may be due to the very small number of patients who required it (n = 8, all in the non-arrhythmia group)

Most arrhythmias in the current study resolved spontaneously within the first 12 hours after surgery (49%), with very few requiring intervention, such as pacemaker implantation. This emphasises that most arrhythmias following paediatric CHD surgery are transient and may not necessitate aggressive management, further highlighting the importance of continuous monitoring and supportive care in the early postoperative period. However, the fact that a small subset of patients required permanent pacemaker implantation for persistent CHB underscores the need for vigilance in managing more severe arrhythmias, as this condition can have long-term implications for patient health.

Different arrhythmias were not uniformly distributed across surgical subgroups but tended to cluster with specific congenital lesions and their repairs. JET was the most frequent postoperative arrhythmia, particularly after TOF repairs, AVSD repairs and arterial switch operations, consistent with prior reports linking JET to longer bypass times and ventricular incisions.^59^ CHB was strongly associated with AVSD and inlet VSD repairs, reflecting the proximity of surgical dissection to the atrioventricular conduction tissue; 2 cases required permanent pacemaker implantation in this study's population. SVT and atrial tachyarrhythmias were most often observed following atrial-level repairs such as PAPVD repair and Fontan procedures, where atrial suture lines may predispose to re-entrant arrhythmias. VT, although uncommon, was reported in patients undergoing single-ventricle palliation (Norwood/Fontan) and complex left ventricular outflow tract reconstructions. These findings emphasise that the type of arrhythmia is closely related to the underlying lesion and surgical approach, and they support prior literature showing higher JET incidence after TOF, AVSD-related CHB and atrial arrhythmias after atrial-level procedures.^78^

Although this study provides valuable insights, it has several limitations. First, the study was conducted at a single institution, which may limit the generalisability of the findings. Additionally, this study only analysed early postoperative arrhythmias; the long-term incidence of arrhythmias post-discharge was not captured. Future studies would benefit from a larger multi-centre cohort and follow-up data to assess the long-term outcomes of patients with postoperative arrhythmias. Finally, while this study identified key risk factors for arrhythmias, the underlying mechanisms remain unclear and warrant further investigation. The pathophysiology of arrhythmias in paediatric CHD surgery is complex and likely involves a combination of genetic, structural and procedural factors.

5. Conclusion

This study highlights that early postoperative arrhythmias occur in 14.2% of paediatric patients following CHD surgery in Oman. JET was the most common arrhythmia observed; prolonged bypass time and history of previous cardiac surgery were identified as independent risk factors for arrhythmia development. Certain cardiac lesions were associated with specific arrhythmias for example, JET was commonly seen post repair of TOF, AVSD and arterial switch operations, CHB is mostly observed after AVSD repair while SVT was commonly associated with repair around the interatrial septum such as PAPVD repair and Fontan procedure. These results will contribute to a better understanding of postoperative arrhythmias in Omani paediatric CHD patients and can inform clinical practices to optimise outcomes in this vulnerable population.

Authors' Contribution

Shamsa Al Kaabi: Conceptualization, Methodology, Software, formal amalysis, Data Curation, Writing – Original, Review & Editing, Visualization. Eslam Mohammed: Software & Resources. Tamer Abosalem: Softward & Resources. Hilal Al Riyami: Conceptualization, Writing – Review & Editing. Ismail Al Abri: Conceptualization, Supervision. Mohammed Al Ghafri: Conceptualization, Methodology, Writing – Review & Editing, Supervision.

Ethics Statement

Ethical approval for this study was obtained from the Institutional Ethics Review Committee of the Royal Hospital (SRC# 27193).

Conflict of Interest

The authors declare no conflicts of interest.

Funding

No funding was received for this study.

Data Availability

Data is available upon reasonable request from the corresponding author.