In Japan, the allocation system for heart transplants is established by a notification from the Ministry of Health, Labour and Welfare regarding the “Selection Criteria for Heart Transplant Recipients.” In Japan’s laws and regulations, Article 2, Paragraph 4 of the Organ Transplantation Act states that “the opportunity to receive transplantation for those in need must be given due consideration to be fair.” Prioritization has been revised in accordance with the various circumstances surrounding transplant medicine at the time, taking into account ① the compatibility between medical organ donors and transplant recipients, ② priority based on the status of treatment and other factors, ③ the effectiveness of heart transplantation, i.e., post-transplant outcomes, and ④ age (upper limit and under 18 years old). The initial selection criteria were established in a notification issued on October 16, 1997, when the “Organ Transplantation Act” came into effect, and had been revised eight times by the end of February 2026.

Background: Pediatric heart transplantation is the only definitive therapy for end-stage heart failure in children, yet donor shortage remains a critical limiting factor worldwide. In the United States, the allocation system has evolved through several revisions since 1988. The 2016 revision, driven by waitlist mortality risk analyses, reduced one-year waitlist mortality from 25% to 19%, particularly benefiting patients with biventricular congenital heart disease (CHD) and body surface area (BSA) of 0.3-0.7 m². Nevertheless, significant heterogeneity in waitlist mortality persists within the current Status 1A category. Key unresolved issues include: (1) the need for highest-priority listing of ECMO-supported patients, consistent with the 2018 adult allocation reform; (2) elevated waitlist mortality among single-ventricle CHD patients on ventricular assist devices (VADs), who may warrant priority equivalent to or greater than dilated cardiomyopathy patients; and (3) insufficient risk stratification by diagnosis in the smallest infants (BSA<0.3 m²), where CHD, hypertrophic cardiomyopathy (HCM), and restrictive cardiomyopathy (RCM) are independently associated with increased waitlist mortality.

Japanese Experience: In Japan, cumulative pediatric heart transplants numbered only 68 by the end of 2022, with a median waitlist duration exceeding 600 days. A 25-year single-center cohort from Osaka University (Narita et al., JTCVS Open, 2026; n＝75) demonstrated outstanding long-term outcomes, with 5- and 10-year survival of 96%, 15-year survival of 86%, and 20-year survival of 67%—substantially exceeding ISHLT global benchmarks. Among adults reached, 76% were employed or enrolled in higher education. Neurological comorbidities were the only significant predictor of poor social reintegration (14% vs. 78%; p<0.01), highlighting the importance of neurodevelopmental support in post-transplant care. Japan introduced a new Status 1A designation in March 2026 to prioritize the most critically ill candidates, representing an important step forward for pediatric heart transplantation in Japan. Nevertheless, careful and ongoing monitoring of Status 1A registration patterns and waitlist mortality trends at each institution will be indispensable, and the insights gained must be translated into further policy refinements.

Conclusions: Continuous refinement of allocation policies—integrating domestic data and international evidence—is essential to expand equitable transplant access for children with end-stage heart failure, particularly high-risk subgroups including CHD, Fontan circulation, and infants with HCM or RCM.

Equitable allocation of donor hearts is a fundamental principle of heart transplantation. An ideal allocation system should prioritize medical urgency, provide equitable access to transplantation, and maximize donor-organ utilization. In Japan, however, prolonged waiting times caused by donor shortage and increasing reliance on durable left ventricular assist devices have highlighted new challenges in the current nationwide allocation system.

Japan’s elongated geography and uneven distribution of transplant centers create substantial regional differences in donor-heart transportation. Longer transport distances may increase ischemic time, limit acceptance of extended-criteria donor hearts, and impose additional logistical and financial burdens on recipients and transplant teams.

We believe that geographic factors should not replace the current nationwide allocation policy but may serve as a complementary consideration in selected situations. Future nationwide studies are warranted to determine whether limited regional prioritization can improve organ utilization while preserving fairness and transparency in the Japanese heart transplantation system.

Background: Japan’s heart transplantation system is characterized by an extremely long waiting period, which contributes to significant mortality on the waiting list. The current allocation system may maintain favorable post-transplant outcomes at the expense of high-risk patients, particularly those with severe heart failure or complications following LVAD implantation. To explore an optimal allocation system for Japan, we investigated risk factors for waiting list mortality.

Method and results: We analyzed 300 patients registered on the heart transplant waiting list at Osaka University between 2014 and 2024. Cox hazard analysis identified age at registration (HR: 1.023) and congenital heart disease (HR: 4.531) as independent risk factors for mortality. In the LVAD cohort (n＝244), right heart failure (HR: 4.582), stroke associated with systemic infection (HR: 5.175), and sudden stroke without preceding infection (HR: 3.158) were significant risk factors. While HeartMate 3 significantly reduced sudden stroke (p<0.001), it did not improve right heart failure or infection-related stroke. Patients with these complications had significantly lower proportions of time at home with LVAD (p<0.001).

Conclusion: Prioritized organ allocation for patients with congenital heart disease, right heart failure, or LVAD-related infections may improve waiting list survival. Reducing hospitalizations in high-risk LVAD patients could also be beneficial from a healthcare economics perspective.

The 2018 revision of the United States heart transplant allocation system introduced a six-tier urgency framework, replacing the prior three-tier classification. This review examines the current allocation structure, donation after circulatory death expansion, multiorgan allocation challenges, geographic sharing policy, and emerging technologies including machine learning risk stratification and xenotransplantation, with comparative insights from Japan.

In April 2026, Japan introduced a highest-priority allocation category, “Status 1A,” into its heart transplantation allocation system. The objective is to appropriately prioritize critically ill patients predicted to die within one month without transplantation, thereby reducing waitlist mortality. This article reviews the background to the introduction of Status 1A, its definition and criteria, the handling of queue order and accrual days, the review and operational processes, and the expected benefits and considerations, while also providing an overview of its alignment with the 2018 United States allocation revision and ISHLT guidelines. In addition, drawing on Japanese data (registry data and publicly available materials from the Japan Organ Transplantation Network [JOT]), we present evaluation metrics for the early post-introduction period.

【Objective】 To investigate the efficacy, pharmacokinetics and safety of tacrolimus hydrate (tacrolimus) administration when initiated 28-7 days prior to a transplantation in living donor renal transplant recipients.

【Design】 Open-label, single-arm, multicenter phase III study (Registration No.: jRCT2080224107)

【Methods】 This study was conducted in donor-specific antibodies or human leukocyte antigen antibodies-positive recipients who planned to receive a living donor renal transplant. The study period was from April 2019 to September 2021. The recipients were administered twice-daily tacrolimus capsules (Prograf) or once-daily extended-release tacrolimus capsules (Graceptor) from 28-7 days prior to the transplantation until 1 day prior to the transplantation. Efficacy was assessed by the percentage of planned transplantation performed after Prograf or Graceptor administration. Change in blood tacrolimus trough concentration and incidence of adverse events were also evaluated for the pharmacokinetics and safety assessment, respectively.

【Results】 Overall, 24 recipients administered at least one dose of Prograf (10 recipients) or Graceptor (14 recipients) were included in the analyses. The mean age (±standard deviation) was 47.9±13.1 years, and the proportion of males was 33.3%. In total, 91.7% of the recipients could receive the transplantation. The mean blood tacrolimus trough concentration generally remained stable at around 10 ng/mL over time. The incidence of adverse events was 87.5%. and adverse drug reactions were observed in 37.5% of the recipients. Serious adverse events were observed in 12.5%, and all of them were judged to be unrelated to Prograf/Graceptor administration. No death was reported.

【Conclusion】 Administering tacrolimus from 28-7 days prior to the transplantation was beneficial in the living donor renal transplant recipients.

【Objective】 Intravenous immunoglobulin (IVIG) has been used to treat antibody-mediated rejection (AMR) ; however, dosage regimens vary across national guidelines. We aimed to evaluate the efficacy of high-dose IVIG (2-4 g/kg) in kidney transplant recipients with AMR.

【Design】 A multicenter, open-label, phase 3 study.

【Methods】 High-dose IVIG therapy (1 g/kg per day, up to four doses) was administered to patients with a pathological diagnosis of active or chronic active AMR, and its efficacy and safety were evaluated six months after treatment initiation. The primary endpoint was renal graft survival six months after IVIG therapy initiation. Secondary endpoints included patient survival six months after initiation, antibody titer over time, percentage of patients with decreased antibody titers, and renal graft function over time. Changes in pathological findings of the renal grafts before and after IVIG administration were evaluated in an exploratory manner. Safety endpoints included adverse events in patients treated with IVIG.

【Results】 Renal graft survival and patient survival at six months were 95.7% [95% confidence interval (CI), 78.1-99.9]. The percentage of patients with decreased HLA antibody titers after IVIG administration was 69.6%. Decreased antibody titers for non-HLA antibodies were observed after IVIG administration. Renal graft function was stable throughout the study period, regardless of AMR type. Post- IVIG histopathological evaluation was performed in 13 (56.5%) of 23 patients, of whom eight showed histopathological improvement in AMR with reduced microvascular inflammation scores after IVIG administration. Adverse reactions were noted in 16 (64.0%) of 25 patients who underwent the treatment protocol; however, all were transient.

【Conclusions】 These results suggest that high-dose IVIG (1 g/kg/day, up to four doses) is a promising treatment for AMR.

【Objective】 The number of deceased donors in Japan has been increasing in recent years. This study aimed to evaluate temporal changes in the acceptance of heart, lung, and liver transplants at the University of Tokyo Hospital and to assess the impact of institutional strategies on acceptance capacity.

【Design】 A retrospective descriptive analysis of deceased-donor organ transplantation acceptance at a single tertiary referral center.

【Methods】 All deceased-donor organ donation cases in Japan between January 2021 and December 2025 were identified using publicly available data from the Japan Organ Transplant Network. For each donor case, the responses of the University of Tokyo Hospital to heart, lung, and liver offers were reviewed and aggregated. Acceptance rates for medically eligible donor offers were calculated according to the number of organs offered on the same day and the day of the week. These findings were examined in relation to changes in institutional surgical capacity and internal operational policies.

【Results】 The number of deceased-donor organ transplants performed at the University of Tokyo Hospital increased steadily, reaching 107 cases in 2025. The overall acceptance rate declined to 74.2% in 2023 but recovered to 90.5% by 2025. Acceptance on weekdays reached 100% in 2025. Although acceptance rates on weekends and holidays decreased to approximately 75% during 2023-2024, they improved to 86.1% in 2025. Acceptance remained 100% when a single organ was offered on a given day and reached 94.7% for two-organ offers in 2025; however, acceptance was limited to 66.7% when offers for three organs occurred simultaneously. On weekdays, acceptance capacity was improved by distributing surgical slots among transplant departments and prioritizing substitution for scheduled elective surgeries. On weekends and holidays, optimization of nursing and anesthesiology staffing enabled acceptance of up to two organs in most cases.

【Conclusion】 Institutional capacity constraints emerged in 2023 in response to a rapid increase in deceased-donor organ offers. Subsequent coordinated efforts across departments improved acceptance capacity by 2025. While challenges remain for simultaneous three-organ offers, particularly on weekends and holidays, further expansion of acceptance capacity through institutional efforts alone may be limited.

A total of 1,901 kidney transplants including 1,668 from living donors, 16 from non-heart-beating donors and 217 from heart-beating donors were performed in 2024 in Japan. The data obtained from the Japanese Renal Transplant Registry are shown and analyzed in this annual report. The characteristics of recipients and donors such as relationships, original diseases, duration of dialysis therapy, blood transfusion, status of viral antigens and antibodies, pretransplant complications, causes of death of deceased donors, ischemic time and histocompatibilities are described. In addition, immunosuppressants used initially and other treatments are analyzed. We also report the results of follow-up survey for recipients and living donors.