Unmasking of a Sinus Venosus Atrial Septal Defect During Right Coronary Artery Myocardial Infarction

BACKGROUND: A sinus venosus defect is the least common form of atrial septal defect (ASD). Both sinus venosus ASD and right ventricular (RV) infarction are characterized by RV dysfunction, right heart failure, and arrhythmias. CASE SUMMARY: A young man with acute occlusion of a small right coronary artery, RV infarction, and cardiogenic shock was suspected of having an underlying ASD because of disproportionate RV and right atrial enlargement, hypoxemia, and prolonged hypotension. ASD identification allowed corrective surgery for ASD as well as coronary artery bypass surgery after his infarction. DISCUSSION: Underlying congenital heart disease should be suspected in the setting of disproportionate right-sided chamber enlargement and hypoxemia in acute coronary syndromes. TAKE-HOME MESSAGE: This case demonstrates the vulnerability of a chronic volume-overloaded RV to acute myocardial injury and the importance of suspecting underlying congenital heart disease in the presence of disproportionate right atrial enlargement.