A Temperature Shift in Donor Heart Storage

A warmer storage temperature for donor hearts—10°C instead of the traditional 4–8°C—was linked to a fivefold reduction in early graft dysfunction and a near ten-point improvement in one-year survival, according to a retrospective study published in Circulation: Heart Failure. The analysis, covering 365 adult heart transplants at Vanderbilt University Medical Center and Duke University from 2020 to 2025, found that grafts kept in the 10°C system had primary graft dysfunction in just 2.9% of cases, compared with 14.6% for those stored at the colder range.

The study, led by Dr. Aaron Williams of Vanderbilt, also reported far less need for post-bypass mechanical circulatory support and no right ventricular dysfunction in the warmer-storage group. These outcomes emerged despite the 10°C grafts being used in higher-risk situations—older donors, older recipients, more mismatches and redo procedures—suggesting the preservation temperature itself improved the heart’s tolerance to ischemia.

In an accompanying editorial, University of Michigan physicians Yuliya Tipograf and Monica Colvin noted that hypothermia, long considered a blanket protective strategy, can itself damage proteins, conduction tissue and diastolic function. The new data add to a growing body of evidence that a slightly warmer hold—already under study in donor lungs—may widen the ischemic-time window and make previously declined hearts usable.

However, the study’s design carries a critical limitation: almost all 10°C cases were done at Vanderbilt after its 2023 protocol change, while nearly all 4–8°C cases came from Duke. Propensity matching cannot fully separate the effect of temperature from differences in surgical technique, perioperative care, and secular improvements at a single center. The authors and editorialists agree that a multicenter randomized trial stratifying by site and ischemic time is now essential.

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Behind the Early Promise of Ten-Degree Preservation

Where the Ten-Degree Edge Might Come From

The hypothesis driving the shift is that extreme cold, while slowing metabolism, also triggers protein denaturation and irreversible diastolic injury—the very insults that can render a marginal heart untransplantable. A 10°C hold may balance ischemic protection with less structural damage. The lung-transplant literature has already shown promising results at the same temperature, and a randomized trial in lung allografts is underway, giving the heart-transplant community confidence that the effect may be reproducible.

A Device Market Shaped by Evidence

The study pitted two commercial cold-storage systems against each other in practice: the Traferox system (operating at 10°C) and the Paragonix SherpaPak (typically 4–8°C). While the comparison is confounded by system design and center, a clear clinical advantage could tilt the market. If later trials confirm that 10°C is superior regardless of the delivering device, Paragonix may need to retool its offering or risk losing share. Conversely, if the effect is tied to Vanderbilt’s specific protocols, the commercial impact may remain muted.

The Editorialists’ Case for a Definitive Trial

Tipograf and Colvin argue that the field now has “a well-defined, eminently testable question”—one that any transplant center could change tomorrow. They propose a non-industry-sponsored, multicenter trial that randomizes hearts to 10°C versus 4–8°C storage, stratified by center and ischemic time, and powered for severe primary graft dysfunction. Such a study would isolate temperature from the institutional confounders that weaken the current retrospective data. Until that trial is completed, hospitals face a practical dilemma: adopt a protocol that shows a large effect in a high-volume center, or wait for randomized evidence.

What the Findings Mean for Transplant Programs

  • Transplant program directors should benchmark their current early graft dysfunction rates against the 14.6% reported for 4–8°C storage in this study. If your program’s performance is worse, assess whether temperature protocol is a contributing factor.
  • Centers considering a switch to 10°C preservation should collect rigorous, risk-adjusted data during any transition period, preferably within a registry or multi-center collaborative, to help build the evidence base.
  • Administrators evaluating device contracts should maintain flexibility until the results of the proposed randomized trial are known, and push suppliers for temperature-control capabilities beyond the traditional 4–8°C range.
  • For device companies, the study signals a potential shift in the standard of care; Paragonix should consider developing or acquiring a 10°C-compatible platform to defend its position, while Traferox should invest in centers willing to generate randomized data using its system.

Risk & Opportunity Assessment

Commercial RiskMediumIf 10°C becomes standard, hospitals may abandon Paragonix’s SherpaPak for devices capable of warmer storage, but the confounding by center weakens immediate commercial pressure.
Competitive RiskHighParagonix faces a direct displacement risk from Traferox or new entrants should randomized trials confirm 10°C superiority and decouple temperature from device brand.
Regulatory RiskLowBoth devices are already cleared; a change in preservation temperature does not necessarily require new clearance, but labeling or guidelines could evolve.
Reputation RiskMediumTransplant programs that continue using only 4–8°C storage without evaluating alternatives may face questions about patient outcomes if real-world complication rates diverge.
Technology DisruptionHighThe shift from ice-based storage to precisely temperature-controlled commercial systems is already underway; a 10°C standard would accelerate that transition and render older methods obsolete.
Commercial OpportunityHighTraferox stands to gain significant market share if its 10°C system is validated as the new standard, while other manufacturers can enter a redefined preservation market.