Aorta-right atrium tunnel and mitral valve prolapse complicated with flail leaflet: a case report of a multimodality approach for an accurate diagnosis.

Background: An aorta-right atrial tunnel (ARAT) is a rare congenital cardiac anomaly that connects the aorta at any coronary sinus to the right atrium. Its cause remains unclear and may involve abnormal origins of the coronary arteries. There is no established link between ARAT and mitral valve prolapse (MVP). Diagnosing ARAT can be challenging, often necessitating multiple imaging techniques, while its management is complex and is further complicated by the association with MVP in our patient. Case summary: We report a case of a 46-year-old man admitted for dyspnoea and palpitations. Thirteen years prior, he had been diagnosed with a cardiac murmur. Echocardiography revealed ARAT and MVP complicated by a flail leaflet and severe regurgitation. AngioCT confirmed the right coronary sinus as the origin of the ARAT and demonstrated the right coronary artery (RCA) arising deep within the tunnel. Cardiac catheterisation identified unclassified pulmonary hypertension due to a left-to-right shunt, along with severe mitral regurgitation. Given the unfavourable anatomy for interventional treatment and the patient's decline in surgery despite multiple consultations, our team opted for conservative management. Currently, the patient's clinical status and echocardiographic parameters remain stable. Discussion: ARAT is a complex congenital disorder that presents diagnostic and treatment challenges, requiring multimodal imaging and teamwork. Since the RCA originates deep within the tunnel and is associated with MVP complicated by flail leaflet and severe regurgitation, we recommend surgical intervention as the appropriate treatment approach. Considering the patient's preferences, conservative treatment was chosen.