Combined heart and other organ transplants in Spain: Current review of clinical outcomes. COMBI Study

BACKGROUND: Combined heart transplantation (HTx) with other organs is an established intervention when both organs fail simultaneously or when a noncardiac organ fails after HTx. This study aimed to describe the Spanish experience with this transplant modality and to analyze survival outcomes. METHODS: This is a retrospective study based on the Spanish Heart Transplant Registry (1998-2024). Pediatric HTx and patients with previous transplants of other organs were excluded. Patients were classified into isolated HTx (n = 6663), simultaneous combined HTx (n = 147; kidney:60; lung:71; liver:16), and delayed combined HTx (n = 110; kidney:72; hematopoietic stem cells [HSC]:27; liver:10; lung:1). Combined HTx accounted for 3.9% of the total. RESULTS: For simultaneous combined procedures, 30-day survival rates were: HTx+kidney: 84%; HTx+liver: 88%; HTx+lung: 73% (p = 0.034); 5-year survival rates were: 64%, 74%, and 41%, respectively (p = 0.0001). In delayed combined HTx, early mortality was low across all types. Five-year survival rates were: HTx+kidney: 73%; HTx+liver: 67%; HTx+HSC: 59% (p = 0.39). An elective isolated HTx showed better results at 10-year survival than combined HTx, both simultaneous and delayed (p = 0.004). CONCLUSIONS: Combined HTx accounts for around 4% of total HTx. Simultaneous heart-liver transplantation provides the best outcomes, while heart-lung transplantation carries the highest risk. Delayed combined HTx shows good early survival.