Most common long-term complication of an unrepaired atrial septal defect?

• A. Aortic regurgitation
• B. Pulmonary hypertension due to Eisenmenger syndrome
• C. Systemic hypertension
• D. Myocardial infarction

Answer: (B)

Chronic left-to-right shunting through an unrepaired atrial septal defect causes increased blood flow to the lungs, prompting progressive changes in the pulmonary vessels. Over time this leads to pulmonary hypertension as the pulmonary vascular resistance rises. When that resistance becomes sufficiently high, the direction of the shunt can reverse, turning into a right-to-left flow—Eisenmenger syndrome. This reversal produces cyanosis, clubbing, and polycythemia and marks the long-term complication most commonly seen with an unrepaired ASD. Other potential issues like aortic regurgitation or systemic hypertension aren’t driven by this defect in the same way, and myocardial infarction isn’t a typical consequence.