Temporal trends in the use and outcomes of temporary mechanical circulatory support as a bridge to cardiac transplantation in Spain. Final report of the ASIS-TC study

[Abstract] Background: We aimed to describe recent trends in the use and outcomes of temporary mechanical circulatory support (MCS) as a bridge to heart transplantation (HTx) in Spain. Methods: Retrospective case-by-case analysis of 1,036 patients listed for emergency HTx while on temporary MCS in 16 Spanish institutions from January 1st, 2010 to December 31st, 2020. Patients were classified in 3 eras according to changes in donor allocation criteria (Era 1: January 2010/May 2014; Era 2: June 2014/May 2017; Era 3: June 2017/December 2020). Results: Over time, the proportion of candidates listed with intra-aortic balloon pumps decreased (Era 1 = 55.9%, Era 2 = 32%, Era 3 = 0.9%; p < 0.001), while the proportion of candidates listed with surgical continuous-flow temporary VADs (Era 1 = 10.6%, Era 2 = 32%, Era 3 = 49.1%; p < 0.001) and percutaneous VADs (Era 1 = 0.3%, Era 2 = 6.3%; Era 3 = 17.2%; p < 0.001) increased. Rates of HTx increased from Era 1 (79.4%) to Era 2 (87.8%), and Era 3 (87%) (p = 0.004), while rates of death before HTx decreased (Era 1 = 17.7%; Era 2 = 11%, Era 3 = 12.4%; p = 0.037) Median time from listing to HTx increased in patients supported with intra-aortic balloon pumps (Era 1 = 8 days, Era 2 = 15 days; p < 0.001) but remained stable in other candidates (Era 1 = 6 days; Era 2 = 5 days; Era 3 = 6 days; p = 0.134). One-year post-transplant survival was 71.4% in Era 1, 79.3% in Era 2, and 76.5% in Era 3 (p = 0.112). Preoperative bridging with ECMO was associated with increased 1-year post-transplant mortality (adjusted HR=1.71; 95% CI 1.15-2.53; p = 0.008). Conclusions: During the period 2010 to 2020, successive changes in the Spanish organ allocation protocol were followed by a significant increase of the rate of HTx and a significant reduction of waiting list mortality in candidates supported with temporary MCS. One-year post-transplant survival rates remained acceptable.