Staged Therapeutic Approach to Concomitant Severe Aortic Stenosis and Atrial Septal Defect: Addressing Dual Mechanisms of Heart Failure—Case Report and Literature Review

Background: Severe aortic stenosis (AS) remains the most prevalent primary valvular disease in Europe and North America, causing heart failure (HF), with pulmonary hypertension (PH) occurring in up to 75% of symptomatic patients. The coexistence of AS and atrial septal defect (ASD) is rare and may generate dual mechanisms of PH, complicating both diagnosis and management. Case summary and review: We report a 78-year-old patient with symptomatic severe AS and right heart failure, in whom an unrecognized secundum ASD with significant left-to-right shunt was identified as a major contributor to persistent HF and right ventricular (RV) dysfunction. Due to prohibitive surgical risk, a staged interventional strategy was decided: transcatheter aortic valve implantation (TAVI), followed by cardiac catheterization and ultimately by percutaneous ASD closure. Marked clinical benefit with the reduction of the RV dimensions and improved systolic function were observed at one year follow-up. A focused review of the literature was conducted to contextualize the pathophysiological mechanisms, diagnostic challenges, and therapeutic strategies in patients with coexisting AS and ASD. Conclusions: This case emphasizes the importance of comprehensive hemodynamic assessment in AS complicated by PH and HF, particularly in the presence of congenital anomalies such as ASD.