What are the long‑term complications of an atrial septal defect?

Long-Term Complications of Atrial Septal Defect

Patients with unclosed atrial septal defects face significantly increased mortality and serious cardiovascular complications that worsen with age, including atrial arrhythmias, right ventricular dysfunction, pulmonary hypertension, stroke, and heart failure—making timely closure before age 25-30 critical for preventing these outcomes. 1, 2, 3

Mortality Risk

• Overall mortality is increased 1.72-fold compared to the general population in patients with ASD, even including those who undergo closure 2
• Survival without closure drops dramatically with age: 25-year survival rates decline from 96% in small defects to only 42% in those who develop Eisenmenger syndrome 1
• Age at closure is the strongest predictor of long-term survival: patients operated on before age 25 have normal life expectancy, while those closed after age 41 have only 40% survival at 27 years versus 59% in matched controls 3
• Transcatheter closure before age 30 normalizes mortality risk (mortality risk ratio 1.58 for closure <30 years vs 0.65 for transcatheter closure overall) 2

Cardiovascular Complications

Arrhythmias

• Atrial fibrillation and supraventricular tachyarrhythmias increase dramatically with age, affecting up to 67% of patients with associated lesions by age 45 1
• Risk of new-onset atrial fibrillation is 2.45-fold higher even after transcatheter closure 4
• Symptomatic arrhythmias occur in 16% of patients at 35-year follow-up after surgical closure, with 6% requiring pacemaker implantation 5
• Sinus venosus defects carry additional risk of sinus node dysfunction and low atrial rhythms 1

Right Ventricular Dysfunction

• Right ventricular ejection fraction is reduced in 31% of patients at long-term follow-up (35 years), even after early surgical closure 5
• Right ventricular dilation occurs in 20% of patients despite successful closure in childhood 5
• Progressive RV failure develops from chronic volume overload, accelerated by adult comorbidities like hypertension, diabetes, and ischemic heart disease that reduce LV compliance and increase left-to-right shunting 1

Pulmonary Hypertension and Eisenmenger Syndrome

• Pulmonary vascular disease risk is higher in females and older adults with untreated defects, representing a potentially lethal complication 6
• Eisenmenger syndrome develops when pulmonary vascular resistance reaches systemic levels, causing shunt reversal and cyanosis with 25-year survival of only 42% 1
• Elevated pulmonary artery pressure before operation is an independent predictor of reduced long-term survival 3

Neurological Complications

• Stroke risk is increased 1.89-fold in patients with ASD compared to controls 2
• Paradoxical embolism can occur through right-to-left shunting, particularly with associated patent foramen ovale 1
• Migraine risk is 3.61-fold higher even after transcatheter closure 4

Other Cardiac Complications

• Ischemic heart disease mortality is increased 1.62-fold, with a 1.73-fold higher risk of new-onset disease even after closure 2, 4
• Ventricular tachycardia/fibrillation risk is 3.54-fold higher after transcatheter closure 4
• AV conduction disorders occur 3.60 times more frequently following closure 4
• Infective endocarditis risk is increased, particularly involving tricuspid and pulmonic valves in unrepaired defects 1

Functional Decline

• Exercise intolerance increases with advancing age in untreated patients 6
• Heart failure develops in 25% of patients with isolated defects and 67% with associated lesions by age 45 1
• Late cardiac failure is significantly more frequent when repair is performed after age 25 3

Critical Pitfalls to Avoid

• Do not delay closure beyond age 25-30 years: this is the critical window where closure prevents long-term complications and normalizes life expectancy 2, 3
• Do not assume closure eliminates all risk: even after successful closure, patients require lifelong surveillance for atrial fibrillation, heart failure, and other cardiovascular complications 4, 5
• Do not miss sinus venosus defects: these require investigation in any adult presenting with atrial arrhythmia and dilated RV, as they often coexist with partial anomalous pulmonary venous return 1
• Do not close defects in established Eisenmenger syndrome: this carries unacceptably high mortality risk unless net shunt remains left-to-right with PAH therapies 1