Atrial Septal Defect in Pregnancy: Clinical Scenarios and Recommendations from the 2025 European Society of Cardiology Guidelines for the Management of Cardiovascular Disease and Pregnancy

Atrial septal defect (ASD) is a common congenital heart condition, accounting for approximately 10% of all congenital heart diseases diagnosed in women of reproductive age, with a prevalence of 1.6–2.5 per 1,000 live births. Advances in paediatric cardiology and surgical repair have enabled an increasing number of women with either repaired or unrepaired ASD to reach childbearing age and consider pregnancy. The physiological changes of pregnancy, including an expanding circulating blood volume and elevated cardiac output, can exacerbate the left-to-right shunt through an ASD, leading to progressive right ventricular (RV) volume overload. As a result, the risk of maternal arrhythmia, especially AF and atrial flutter, as well as right heart failure, is heightened, posing complications during the peripartum period.

The peripartum risks in women with ASD depend on the defect size, severity of shunt, pulmonary vascular resistance, and prior repair status. Large cohort and registry studies show that while most women with isolated, uncomplicated ASD tolerate pregnancy well, those with unrepaired defects accompanied by evidence of significant RV overload or pulmonary hypertension face a substantially higher risk of adverse outcomes. According to the modified WHO (mWHO) criteria, the presence of an unrepaired ASD is classified as class 2; however, when associated with cyanosis or pulmonary arterial hypertension, it may fall into class 4, indicating a markedly increased risk of maternal cardiac events.¹ Maternal complications in patients with ASD include pre-eclampsia, paradoxical embolism and arrhythmia, while fetal risks such as small-for-gestational-age birth and a higher incidence of inherited congenital heart disease have been reported in women with ASD compared with the general population.²

High-risk Features for ASD in Pregnancy: Right Heart Failure, Arrhythmia

ASDs are often detected incidentally, either as a cardiac murmur on physical examination or via imaging findings such as an increased cardiothoracic ratio or prominent pulmonary vasculature. High-risk features for ASD in pregnancy, as highlighted by recent international guidelines and expert consensus, include the development of right heart failure, arrhythmia, pulmonary hypertension, cyanosis, prior thromboembolic events and significant RV dysfunction. Women with unrepaired ASD who have RV volume overload are at an increased risk of developing right heart failure.

During pregnancy, plasma volume increases by up to 50%, while red cell mass rises by 20–30%, resulting in relative physiological anaemia. This volume expansion leads to a 30–50% higher cardiac output, peaking between 28 and 30 weeks, driven primarily by increased stroke volume and a heart rate elevation of 10–20 BPM.² These haemodynamic changes can accentuate left-to-right shunting, thereby increasing RV preload and precipitating heart failure symptoms.

Severe pulmonary hypertension or Eisenmenger syndrome is the strongest contraindication to pregnancy, given the extremely high maternal morbidity and mortality rates, with maternal mortality reaching up to 50% in Eisenmenger syndrome.³ The European Society of Cardiology (ESC) guidelines in 2025 specifically advise that pregnancy is contraindicated in women with severe pulmonary hypertension secondary to ASD (mWHO class 4), and emphasise the importance of shared decision-making in reproductive planning in women with these risk factors.⁴

Arrhythmia, occurring in up to 5% of pregnant women with unrepaired ASD, is the most common cardiac complication.² The risk is even higher in women with dilated right atria or a prior history of arrhythmia. Haemodynamic stress, autonomic alterations, and the hypercoagulable state of pregnancy amplify the susceptibility to arrhythmias, which can be associated with adverse maternal and fetal outcomes.²

Key Updates in the 2025 ESC Guidelines for the Management of Cardiovascular Disease and Pregnancy

The 2025 ESC guidelines for the management of cardiovascular disease and pregnancy introduce several key updates in the management of ASD during pregnancy. Compared with previous guidelines, there is now a greater emphasis on individualised risk stratification, multidisciplinary care and shared decision-making. Specifically, the guidelines recommend risk stratification in women with ASD by defect type, shunt size, RV dimension, pulmonary pressure and history of arrhythmia. This expanded risk assessment leads to more precise recommendations regarding pre-conception counselling, timing and approach to intervention, as well as surveillance during pregnancy.

A pivotal change in the 2025 ESC update is the formal establishment of the pregnancy heart team, comprising cardiologists, anaesthetists, obstetricians and clinical nurse specialists. This multidisciplinary team coordinates care from pre-conception through to pregnancy, delivery, postpartum and long-term follow-up, particularly in cases involving significant left-to-right shunt, right heart dilation, pulmonary hypertension or arrhythmia.

The guidelines emphasise that the closure of significant ASDs, preferably via a transcatheter approach, should be performed prior to conception whenever possible. In women with severe pulmonary hypertension or Eisenmenger syndrome, pregnancy remains contraindicated due to substantial maternal and fetal risks, and these risks must be clearly discussed as part of shared decision-making.

Additionally, the 2025 ESC guidelines recommend vaginal delivery for women with repaired or haemodynamically insignificant ASDs, reserving Caesarean section for obstetric or severe cardiac indications (recommendation class 1, evidence level b). Women’s autonomy is prioritised through comprehensive counselling, documentation of preferences, and integration of recommendations from the pregnancy heart team.

Compared with the 2018 ESC guidelines, these updates reflect a move away from a simple mWHO risk classification approach towards a more nuanced, patient-centred model that integrates new evidence on ventricular function, arrhythmia risk, and the effects of volume loading during pregnancy. The principle that significant shunts or complications should be addressed prior to pregnancy remains unchanged; the process for multidisciplinary evaluation and shared decision-making is now more clearly defined.

When compared with the US guidelines, specifically the American Heart Association/American College of Cardiology (AHA/ACC) 2018 and 2020 guidelines on adult congenital heart disease, along with expert consensus statements from the 2023 AHA/ACC/American College of Chest Physicians/Heart Rhythm Society expert consensus statements on congenital heart disease and pregnancy, the ESC approach is broadly aligned in recommending pre-conception closure of significant ASD, regular follow-up, and individualised management of arrhythmia or pulmonary hypertension.^5–7 Both sets of guidance agree that pregnancy is generally well tolerated in women with small, haemodynamically insignificant or repaired ASDs, and that vaginal birth is preferred unless there are specific cardiac or obstetric indications for Caesarean section. A list of the relevant recommendations, class and level of recommendations from the latest 2025 guidelines is given in Table 1.

Guideline Recommendations for Atrial Septal Defect Management in Pregnancy

For women with ASD, the guidelines recommend a comprehensive risk stratification approach using the mWHO 2.0 classification, which integrates anatomical defect characteristics, haemodynamic burden (quantified by pulmonary-to-systemic flow ratio Qp : Qs >2.2:1 and RV end-diastolic diameter >32 mm), pulmonary artery systolic pressure thresholds and arrhythmia substrate to categorise maternal risk from class 1 (minimal risk) to class 4 (extreme risk).

Pre-conception counselling should incorporate discussion of ASD closure for haemodynamically significant defects (Qp : Qs >2.2:1). During pregnancy, echocardiographic surveillance is stratified by the mWHO class, with uncomplicated ASDs (class 2) requiring baseline assessment and repeat evaluation at 28–32 weeks of gestation when the haemodynamic burden peaks, while more complex lesions warrant monthly monitoring from 20 weeks onwards. The 2025 guidelines introduce a class 2a, evidence level b recommendation for serial natriuretic peptide monitoring in women with mWHO class 3–4 conditions (B-type natriuretic peptide/N-terminal pro-B-type natriuretic peptide [BNP/NT-proBNP]), recognising that elevated levels indicate significant cardiac stress and guide therapeutic interventions. Right heart catheterisation (RHC) is reserved for diagnostic uncertainty, particularly to differentiate causes of de novo pulmonary hypertension and of secondary pulmonary hypertension from pulmonary arterial hypertension. Specific domains of counselling based on the class of ASD and the involvement of the pregnancy heart team are further discussed in Table 2.

Case Examples

This review presents two real-life scenarios of ASD encountered during pregnancy in a tertiary cardiology centre and examines their management in the context of the latest 2025 ESC guidelines.

Case 1

A 40-year-old woman, gravida 1 para 0, with unremarkable past health, presented at 12 weeks of gestation with progressive exertional dyspnoea and mild pedal oedema. Initial laboratory investigations showed no proteinuria on spot urine testing, with a normal thyroid and haemoglobin level. On physical examination, her blood pressure was normal, and there was a soft grade 2/6 systolic murmur at the lower left sternal border. Transthoracic echocardiogram demonstrated a large secundum-type ASD measuring 1.74 × 1.88 cm, with a moderately dilated RV. The RV systolic pressure (RVSP) was 24 mmHg, with a peak tricuspid regurgitation velocity of 2.3 m/s and a right atrial pressure of 3 mmHg (Figure 1).

Approach and Discussion

Management of a pregnant woman with a large secundum ASD and mild symptoms, according to 2025 ESC guidelines, begins with referral to a pregnancy heart team for individualised assessment. The multidisciplinary team typically consists of specialists in congenital cardiology, maternal–fetal medicine and anaesthesiology.

Risk Stratification

Based on her presenting symptoms and size of the shunt, the patient was deemed to be at mWHO class 2 (moderate risk) for maternal cardiac complications given the absence of heart failure symptoms and a preserved RV systolic function. Further evaluation should include baseline ECG, NT-proBNP and serial echocardiography to monitor RV function, size, shunt quantification and pulmonary pressures throughout pregnancy.

Role of Cardiac Biomarkers

Cardiac biomarkers, NT-proBNP, BNP and troponin (T and I), are increasingly used for risk assessment in pregnant women with pre-existing cardiac conditions such as ASD. Although NT-proBNP and BNP may be modestly higher in the population of healthy pregnant women compared with non-pregnant women, values generally remain stable across trimesters despite the haemodynamic fluctuations in pregnancy (see Table 3 for normal ranges and upper reference limits).^8–10

An elevated NT-proBNP or BNP is a validated marker of myocardial stress and may indicate increased risk of heart failure during pregnancy. Persistently high or rising NT-proBNP levels during gestation and the postpartum period have been associated with heart failure, arrhythmia, and worse maternal outcomes among women with congenital heart disease. The 2025 ESC guidelines recommend considering NT-proBNP and BNP measurement in women with known heart disease, both prior to and during pregnancy, to aid risk stratification (class 2a recommendation).⁴ NT-proBNP above 200 pg/ml or BNP above 50 pg/ml have been associated with adverse outcomes in some cohorts.¹⁰ Serial assessment is recommended in high-risk groups, for which significant increases from baseline or persistent elevation should prompt more frequent surveillance and potential adjustment of management strategies.

In this case, the NT-proBNP level was 60 pg/ml in the first trimester. This remained below the median values of 68 and 59 pg/ml in the second and third trimesters, respectively.

High-sensitivity cardiac troponin I retains its strong negative predictive value for myocardial injury during pregnancy. Mild elevations may occasionally be observed in pregnant women with underlying cardiac conditions, particularly around the time of delivery. Any troponin elevation in pregnancy should always prompt comprehensive investigation for acute cardiac pathology.¹⁰

Medical Management and Monitoring

In the absence of severe heart failure or pulmonary hypertension, conservative management with close monitoring for symptom progression is recommended. Diuretics may be considered for symptomatic fluid overload, but all pharmacological decisions should balance maternal benefit against fetal safety. Antenatal anticoagulation is generally not indicated unless atrial arrhythmias or additional risk factors are present.

In this case, the RV function was preserved and there was no evidence of pulmonary hypertension. Thus, continuation of non-invasive monitoring including serial echocardiography was sufficient during the pregnancy. RHC and transcatheter ASD closure can be deferred until after delivery, unless the patient develops significant RV dysfunction on imaging or clinically in a fluid overloaded state.

Case 2

A 40-year-old woman, gravida 1 para 0, at 24 weeks of gestation with a history of severe idiopathic thoracolumbar scoliosis and who previously declined orthopaedic reconstruction (Figure 2), presented with reduced exercise tolerance and exertional dyspnoea. She had no limb swelling or history of syncope. Laboratory assessments showed negative urine protein, normal thyroid function and haemoglobin levels, and a NT-ProBNP of 142 pg/l in the second trimester. On physical examination, BMI was 21 kg/m², blood pressure was in the normal range, and a grade 3/6 systolic murmur was auscultated at the lower left sternal border.

Transthoracic echocardiogram demonstrated marked RV dilatation with a large ASD. A D-shaped left ventricle was observed, with evidence of intermittent right-to-left shunting during Valsalva manoeuvre as demonstrated by agitated saline contrast. The estimated RVSP was significantly elevated at approximately 50 mmHg (estimated right atrial pressure estimated at 8 mmHg). Despite the pulmonary hypertension, RV systolic function remained preserved (Figure 3 ).

Approach and Discussion

As in case 1, management should begin with established care under a specialised multidisciplinary team, including cardiologists, obstetricians, anaesthetists and respiratory physicians. This collaborative approach is essential for comprehensive risk evaluation and joint decision-making.

Risk Stratification and Monitoring

This case features major risk factors: a large, haemodynamically significant ASD with intermittent right-to-left shunt and elevated RVSP, compounded by the restrictive effects of severe thoracolumbar scoliosis. Based on these features, the patient’s risk was stratified as moderate to high (mWHO 3 or higher) for maternal complications. Close monitoring is warranted, with serial assessments of symptoms, oxygen saturation, NT-proBNP and echocardiographic parameters to track RV size, systolic pressure and shunt direction. Given the patient’s severe thoracolumbar scoliosis and reduced exercise tolerance, pulmonary function testing should also be performed to quantify the degree of restrictive lung impairment, and to guide assessment of pregnancy risk, delivery planning and anaesthetic management.

Indications for Invasive Investigation or Transcatheter Intervention

RHC during pregnancy is rarely required in women with ASD but remains an important diagnostic tool when pulmonary pressure or haemodynamics are uncertain, or when clinical and non-invasive findings are incongruent. The 2025 ESC guidelines and expert consensus recommend considering RHC in cases of suspected pulmonary arterial hypertension, unexplained symptom progression, or when precise haemodynamic measurements are critical for therapeutic decisions (class 2a recommendation, level c evidence).

RHC is particularly indicated when echocardiography cannot reliably differentiate between pre- and post-capillary pulmonary hypertension, or when the severity of symptoms (e.g. New York Heart Association [NYHA] class ≥III, significant heart failure) is disproportionate to imaging findings. Concerns with RHC during pregnancy include fetal radiation exposure and maternal procedural risks. Thus, it should be performed in a specialised tertiary centre with appropriate shielding facilities and preferably be arranged after 20 weeks of gestation.

In this case, RHC was justified in accordance with current guidelines, enabling better delineation of pre- versus post-capillary pulmonary hypertension, which facilitates decision-making regarding ASD closure during pregnancy. Prior to the procedure, detailed discussions were held with the patient and her family regarding the indications, procedural risks and potential radiation exposure to the fetus, with reassurance that every effort would be made to minimise radiation according to the ‘as low as reasonably achievable’ (ALARA) principle.

RHC was performed at 25 weeks of gestation under an abdominal radiation shield, with all radiation protection measures implemented in accordance with the guideline-directed ALARA principle. Venous access was obtained via the right antecubital vein rather than the femoral vein (Figure 4 ), reducing the risk of iatrogenic trauma to pelvic vessels, avoiding catheter manipulation near the gravid uterus, and facilitating access to the pulmonary artery while minimising abdominopelvic radiation exposure to the fetus.^11–13

Haemodynamic assessment from RHC showed a large left-to-right interatrial shunt with a Qp:Qs ratio of 2.98:1. The mean pulmonary artery pressure was only marginally elevated at 20 mmHg, which was significantly lower than the estimation of RVSP 50 mmHg from previous echocardiography (Figure 5 ). The greatest step-up in oxygen saturation was observed in the right atrium (SpO₂ 94.5%), consistent with a large left-to-right interatrial shunt. Based on these haemodynamic parameters, the pregnancy heart team concluded that there was no strong evidence of significant pulmonary arterial hypertension, and continuation of pregnancy was deemed appropriate. In view of the favourable haemodynamics and mild symptomatology, transcatheter ASD closure during pregnancy was not considered mandatory. Biweekly follow-up visits were arranged in the third trimester to monitor for any new symptoms, with ongoing multidisciplinary discussions held with the pregnancy heart team.

Serial observations of right heart function remained similar throughout the third trimester. Delivery was performed by Caesarean section for placenta praevia, in accordance with obstetric indications. In this case, prophylactic amoxicillin was administered before delivery for obstetric indications. It should be emphasised that neither the 2025 ESC guidelines on cardiovascular disease in pregnancy nor the 2023 ESC guidelines for the management of endocarditis recommend routine systemic antibiotic prophylaxis for isolated ASD as prophylaxis for infective endocarditis.^4,13

Conclusion

ASD in pregnancy represents a broad spectrum of risk, ranging from uncomplicated cases in which the patients tolerate gestation well to high-risk scenarios requiring intensive multidisciplinary surveillance and intervention.

The two cases illustrated this heterogeneity: case 1 demonstrated that a large secundum ASD with preserved RV function can be managed conservatively without the need for invasive catheterisation. Case 2 highlighted the complexity of management, when significant right heart dilatation, elevated pulmonary pressure and comorbid restrictive lung disease from severe scoliosis necessitated RHC during pregnancy to guide therapeutic decision-making.

The 2025 ESC guidelines for the management of cardiovascular disease and pregnancy provide a robust, patient-centred framework that emphasises individualised risk stratification beyond the traditional mWHO classification, formal establishment of the pregnancy heart team, and shared decision-making with comprehensive documentation of patient preferences. Key practical recommendations are reinforced by these cases, which include the utility of serial NT-proBNP measurement for detecting evolving right heart failure, risk stratification, and the role of RHC in selected patients with ASD during pregnancy.