The structure and organization of the Spanish heart transplant registry have been summarized in previous reports.1 Participation in this registry requires an obligatory annual report, dated December 31, for the preceding year. This report includes all transplant recipients since the last update and an update on the vital status of all patients in the historic series up to this date, as well as the most relevant clinical events encoded in the database.

The centers with heart transplant programs are summarized in table 1. One center performs pediatric transplantation alone, while 5 centers conduct both pediatric and adult transplantation. Two centers are accredited to perform cardiopulmonary transplantation. The most recent center was incorporated into the heart transplant program in 2019, and 2 centers have already completed more than 1000 procedures.

In 2024, 347 procedures were performed, of which 30 (8.6%) were in recipients younger than 18 years, and 112 (32.3%) were in recipients older than 60 years (figure 1). From 1984 to 2024, 10 345 transplants were conducted, including 250 retransplants (2.4%) and 212 multiorgan transplants (2.0%), mainly pulmonary or renal (92 patients each) (table 2). The main analysis focuses on transplants performed in the last 10 years (2015-2024). The trends for the main recipient, donor, surgical procedure, immunosuppression, and survival characteristics have been studied in trienniums (2015-2017, 2018-2020, and 2021-2023).

Figure 1.

Annual number of transplants (1984-2024), total and by age group.

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Continuous variables are expressed as the mean ± standard deviation, and categorical variables as percentages. The nonparametric Kendall tau test and the Wilcoxon test for trends were used to assess temporal trends in the categorical and quantitative variables, respectively. Cumulative survival was estimated using the Kaplan-Meier method, and differences between groups were determined using the log-rank test. Hazard ratios with 95% confidence intervals for the nonadjusted relationship of selected variables with mortality were determined using Cox regression. Differences were considered statistically significant at a 2-tailed P<.05.

In 2024, 347 transplants were performed, marking a 6.8% increase from 2023 and a 24.8% rise compared with 5 years earlier (2020). In the last 10 years, there has been no significant change in recipient age or sex. However, this has led to a gradual increase in recipients with etiologies other than standard dilated cardiomyopathy, both ischemic and nonischemic, although no such increase was observed in 2024. Statistically significant trends show a progressively more favorable recipient profile, evidenced by a lower proportion of transplants performed in patients who had received prior mechanical ventilation (P=.002), as well as lower pulmonary vascular resistance (P<.003) and fewer recipients with elevated pretransplant serum bilirubin levels (P<.001). In contrast, and as noted in the previous report,1 there was an increase in the percentage of urgent transplants (47.0% in 2024), 6.1% more than in 2023 and 25.0% more than in 2022 (figure 2). This trend parallels the increased use of circulatory assist devices (figure 3), because transplant urgency in Spain is linked to the need for circulatory support, which grew from 37.7% in the 2021 to 2023 triennium to 43.2% in 2024 (table 3). This increase was primarily due to greater use of extracorporeal membrane oxygenation, which rose from 23.2% in 2022 to 36.5% in 2023 and 34.7% in 2024 (figure 3).

Figure 2.

Annual percentage of urgent transplants vs the total number (2015-2024). The dotted line indicates the linear adjustment line of the temporal trend.

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Figure 3.

Distribution of the type of pretransplant circulatory support by year (2015-2024). ECMO, extracorporeal membrane oxygenation; VAD, ventricular assist device.

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In 2024, there was a slight uptick in the average donor age and in the proportion of suboptimal donors (> 45 years) (table 4). However, this increase did not alter the significant downward trends observed in the last decade for both variables (figure 4). The proportion of male donors rose again (69.3% in 2024), with a highly significant trend in the last decade (P<.001). This has produced a corresponding decrease in the percentage of transplants performed with a donor-recipient sex mismatch (male recipient, female donor). Up to a fifth of donors in 2024 experienced cardiac arrest during the donation process, reflecting an upward trend in the last decade (table 4). In addition, compared with the significant trend toward shorter ischemia times in previous years, a slight increase was detected in 2024 vs the most recent 3-year period.

Figure 4.

Annual changes in donor age (continuous blue line) and percentage of donors older than 45 years (red bars) (2015-2024). The dotted lines indicate the linear adjustment lines of the temporal trend. This figure is shown in color in the online version of this article. 95%CI, 95% confidence interval.

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The current analysis definitively confirms the trend observed in the previous report toward a highly marked increase in transplants performed using donation after circulatory death (asystole). In 2024, 101 procedures were conducted with this type of donation (29.1% of all transplants in Spain and 38.7% of procedures in centers with active circulatory death donation programs). Overall, 211 transplants using this type of donation have already been performed, representing 13.9% of all procedures since 2020.

The immunosuppression strategies used during the study period are summarized in table 5. In 4 out of 5 patients, the induction immunosuppression comprised basiliximab, while the maintenance immunosuppression consisted of standard triple therapy with tacrolimus, mycophenolate, and steroids. mTOR inhibitors were rarely used.

Survival increased once again compared with previous years. In the last decade, 1- and 5-year posttransplant survival rates were 82.4% and 74.3%, respectively. These figures are significantly higher than those for the entire previous period (75.8% and 65.2%) (figure 5A). In the last 10 years, 1-year survival increased from 80.7% in the 2015 to 2017 triennium to 85.2% from 2021 to 2023 (P=.008) (figure 5B).

Figure 5.

A: comparison of survival curves between the 2015 to 2024 and 1984 to 2014 periods. B: comparison of survival curves from 2015 to 2023 by triennium.

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Table 6 summarizes the unadjusted determinants of survival in the 2015 to 2024 period. Mortality was associated with complex procedures such as urgent transplants, multiorgan transplants, the need for pretransplant mechanical circulatory support, and vulnerable recipients (older age, nondilated etiologies, need for mechanical ventilation, or a history of infection). Notably, transplants performed using donation after circulatory death showed higher crude survival rates.

The causes of death (figure 6) in the first 5 posttransplant years remained unchanged and were dominated by primary graft failure and infection in the first posttransplant year. Acute rejection was a less frequent cause of death during this period. In the last decade, mortality in the first year due to acute rejection and infection has shown a significant downward trend, while the proportion of deaths due to primary graft failure has remained stable (figure 7).

Figure 6.

Main causes of death by time since transplantation in the 2015 to 2024 period. GVD/SCD, graft vascular disease/sudden cardiac death. Each cause of death is reported as a percentage of total patient deaths in the specific period.

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Figure 7.

Changes over time in the main causes of death in the first posttransplant year in the 2015 to 2024 period by triennium.

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