Prognosis for Patients with Sinus Venosus Atrial Septal Defects Without Surgical Repair
Patients with untreated sinus venosus atrial septal defects face significant risks of developing pulmonary arterial hypertension, right ventricular failure, atrial arrhythmias, and potentially Eisenmenger syndrome, with mortality exceeding 50% after age 40. 1, 2
Natural History and Progression
Sinus venosus ASDs represent 5-10% of all atrial septal defects and are commonly associated with partial anomalous pulmonary venous drainage (PAPVD) in approximately 90% of cases, which increases left-to-right shunting and accelerates the development of pulmonary hypertension 3, 4
The risk of developing pulmonary arterial hypertension (PAH) is higher with sinus venosus ASDs compared to secundum ASDs due to their anatomical location and frequent association with anomalous pulmonary venous return 1
Patients with unrepaired ASDs typically remain asymptomatic through childhood and early adulthood, with symptoms commonly developing in the third to fifth decade of life 1
In the EuroHeart survey, approximately 2% of adults with unrepaired ASDs developed Eisenmenger syndrome, though the risk is likely higher specifically for sinus venosus defects 1
Age-Related Complications
Patients under 40 years of age with unrepaired ASDs generally have a better prognosis than those who remain undiagnosed and untreated after age 40 2
The incidence of pulmonary hypertension in patients with unrepaired ASDs ranges from 6% to 17%, with PAH persisting after closure more likely in older patients with larger defects 1
Atrial arrhythmias, particularly atrial fibrillation and flutter, occur in approximately 20% of adults with unrepaired ASDs and increase with age 1
The hemodynamics at follow-up are worse in non-operated ASD patients than in those whose defects have been closed, especially those with moderate or large defects 1
Risk of Right Ventricular Dysfunction
Progressive right ventricular volume overload occurs due to persistent left-to-right shunting, eventually leading to right ventricular dilation and dysfunction 5
Adult comorbidities such as ischemic heart disease, hypertension, or diabetes mellitus can worsen the condition by reducing left ventricular compliance, increasing left atrial pressure, and consequently increasing left-to-right shunting with pulmonary overcirculation 1
In extreme cases, these changes can accelerate right ventricular failure 1
Arrhythmia Development
Sustained atrial flutter or atrial fibrillation develops in a significant proportion of patients with unrepaired ASDs, with risk increasing with age 1
Sinus venosus defects may additionally present with sinus node dysfunction, low atrial rhythm, or atrial arrhythmias due to their proximity to the sinus node 1
The development of atrial arrhythmias has been associated with an increased risk of death and sudden death in some studies 1
Risk of Paradoxical Embolism
Patients with unrepaired ASDs are at risk for paradoxical embolism, which can lead to cerebrovascular events 1
In a randomized study of adults over 40 years with unrepaired ASDs, cerebral embolic events occurred in 2.1% of patients 1
Development of Eisenmenger Syndrome
If left untreated, patients with sinus venosus ASDs may eventually develop Eisenmenger syndrome, where irreversible pulmonary vascular disease leads to right-to-left shunting and cyanosis 2
Once Eisenmenger physiology develops, patients are no longer candidates for defect closure, as this would be contraindicated and potentially harmful 6
Mortality Risk
Adults with unrepaired ASDs over age 40 face a mortality rate exceeding 50%, particularly when complications such as pulmonary hypertension and Eisenmenger syndrome develop 2
The prognosis worsens significantly once severe pulmonary vascular disease develops, with most children with untreated IPAH dying within 1-2 years of diagnosis 1
Comparison to Surgical Outcomes
In contrast to the poor prognosis of untreated sinus venosus ASDs, surgical repair has excellent outcomes with in-hospital mortality rates as low as 0.24% and 30-day mortality rates of 0.5% 3
Long-term complications after surgical repair include atrial fibrillation (3.3%), sinus node dysfunction (6.5%), pacemaker insertion (2.23%), and cerebrovascular accidents (2.03%) 3
These rates are significantly lower than the complications seen in untreated patients, highlighting the importance of timely intervention 3
Special Considerations
Female patients with unrepaired ASDs appear to be at higher risk for developing complications, including pulmonary hypertension and Eisenmenger syndrome 2
Patients with additional risk factors such as obesity or chronic respiratory conditions may experience accelerated progression of pulmonary hypertension if their sinus venosus ASD remains unrepaired 2