Highlight
This multicenter study comparing 10°C versus 4-8°C static cold storage for donor hearts demonstrated superior early graft function, reduced primary graft dysfunction, and improved one-year survival with 10°C preservation despite higher risk donor and recipient profiles.
Additional benefits included less ventricular dysfunction and reduced need for intraaortic balloon pumps, suggesting 10°C as an optimal temperature for cardiac allograft preservation.
Study Background
Heart transplantation remains the definitive treatment for end-stage heart failure, yet donor heart preservation methods significantly influence graft viability and recipient outcomes. Traditionally, static cold storage at 4-8°C has been the standard of care to minimize metabolic demand and ischemic injury during transport. However, recent research indicated that a slightly higher temperature of 10°C may better preserve myocardial tissue while balancing metabolic needs.
Given the critical impact of ischemia-reperfusion injury on transplant success, optimizing preservation temperature is an unmet need to improve early graft function and survival, reduce perioperative complications such as primary graft dysfunction (PGD), and expand donor heart utilization.
Study Design
This retrospective dual-center study conducted at two high-volume transplant centers (Vanderbilt and Duke) evaluated adult recipients undergoing single-organ heart transplants from donation-after-brain-death donors between January 2020 and April 2025.
Exclusion criteria included multiorgan transplants, adult congenital heart disease, and donation-after-circulatory-death donors to maintain cohort homogeneity. Recipients were stratified by preservation temperature of the donor heart: standard 4-8°C versus experimental 10°C static cold storage.
To adjust for clinical confounders, a 3:1 nearest-neighbor propensity score matching was applied ensuring balance in baseline donor and recipient characteristics with standardized mean differences below 20%
Primary endpoints were rates of primary graft dysfunction (PGD), ventricular function assessed by echocardiographic criteria, need for mechanical circulatory support (e.g., intraaortic balloon pump), and one-year recipient survival. Secondary outcomes included cardiac indices and posttransplant hospital length of stay.
Key Findings
The analysis included 365 recipients: 113 in the 10°C group and 252 in the 4-8°C group. Notably, the 10°C group donors were older (median 37 vs. 31 years), had higher rates of sex mismatch, and more frequent undersizing by predicted heart mass ratios. Recipients in the 10°C cohort were also older, with more prior sternotomies and higher baseline serum creatinine, indicating a higher-risk population overall.
Despite these risk factors, the 10°C preservation group exhibited significantly superior outcomes after propensity score matching:
- Primary graft dysfunction occurred in only 2.9% (2/69) versus 14.6% (19/130) in the 4-8°C group (P=0.008).
- Both left and right ventricular dysfunction rates were markedly reduced under 10°C conditions.
- There was less frequent requirement for new intraaortic balloon pump support.
- One-year survival improved to 95.7% versus 86.2% in the 4-8°C cohort (P=0.02).
Cardiac index measurements and length of posttransplant hospitalization did not differ significantly between groups.
Expert Commentary
This landmark multicenter study provides compelling evidence that slight warming of static cold storage from the traditional 4-8°C to 10°C confers cardioprotective benefits in adult heart transplantation.
It is biologically plausible that 10°C better preserves mitochondrial integrity and reduces cold-induced injury without markedly increasing metabolic demand that can exacerbate ischemic damage during storage. These findings align with emerging data in organ preservation that challenge the long-standing paradigm of hypothermic extremes.
Despite the retrospective design, robust propensity matching and a sizable cohort strengthen validity. However, prospective randomized trials remain essential to confirm causality, evaluate optimal temperature ranges, and assess long-term outcomes including allograft vasculopathy and rejection rates.
Clinicians should cautiously consider these findings in the context of existing protocols and resources, but this study may catalyze revisions to heart preservation standards that ultimately expand donor utilization and improve transplant success.
Conclusion
Preservation of donor hearts at 10°C significantly improves early graft function and one-year survival compared with conventional 4-8°C cold storage. This evidence suggests that 10°C is an optimal static cold storage temperature balancing metabolic demands and tissue preservation.
Future prospective studies are warranted to confirm these results and potentially set a new standard for donor heart preservation in adult transplantation.
Funding and Registration
The study was supported by institutional funds from Vanderbilt University and Duke University transplant programs. Registration and detailed methodology are available via institutional clinical research oversight boards.
References
Williams AM, Lima B, Benkert A, Ahmad A, Bommareddi S, Trahanas J, Wang CC, McGann KC, Petrovic M, Devries S, Lowman J, Casalinova S, Kesseli S, Goel D, Lobo A, Esmalian G, Devore A, Keenan J, Milano C, Schlendorf K, Bacchetta M, Shah AS, Schroder J. Donor Heart Preservation at 10 °C Outperforms 4-8 °C With Improved Early Graft Function in Adult Heart Transplantation: A Vanderbilt and Duke Multicenter Study. Circulation. Heart failure. 2026 Aug 5:e014240. PMID: 42554059.
