Management of arrhythmia and heart failure in a 60-year-old with unrepaired D-transposition of the great arteries, atrial septal defect, and partial anomalous pulmonary venous return: a case report.

Background: Dextro-transposition of the great arteries (d-TGA) typically results in death within the first year of life without surgery. Shunts can allow sufficient blood mixing and survival into adulthood; however, survival of patients with unrepaired d-TGA beyond 60 years has not been reported. Case summary: A 60-year-old woman with unrepaired d-TGA, an unrestricted atrial septal defect, and partial anomalous pulmonary venous return presented with recurrent syncope due to atrial tachycardia (AT) following two sessions of radiofrequency catheter ablation (RFCA) and sinus node dysfunction. She had a history of recurrent heart failure (HF) because of severe systemic right ventricle (sRV) dysfunction and tricuspid regurgitation. Multiple inducible ATs persisted even after repeated RFCA, making pacemaker implantation (PMI) and anti-arrhythmic therapy the preferred options. Although transvenous lead implantation was relatively contraindicated due to the presence of an intracardiac shunt, transvenous DDD PMI was deemed the most viable option considering the patient's fragile haemodynamic state. Pacing studies indicated that sRV pacing was superior to left ventricular septal pacing, as it reduced the QRS duration and improved RV synchrony. Following successful sRV septal lead implantation and atrioventricular delay (AVD) optimization, HF symptoms improved, ATs were suppressed with amiodarone, and syncope resolved. The patient remained stable for 2 years with no thromboembolic events under apixaban therapy and no HF or arrhythmia recurrence. Discussion: Although continuous close monitoring is warranted, endocardial pacing, AVD optimization, and medication enabled effective stabilization over 2 years in this rare case of unrepaired d-TGA with bradytachyarrhythmia and sRV dysfunction.