Objective:

To compare hemostatic efficacy and safety of cold-stored platelets with conventional room-temperature platelets in patients undergoing complex cardiac surgery with cardiopulmonary bypass.

Approach:

• Design: Multicenter, randomized, partially blinded, adaptive noninferiority phase 3 trial at 27 sites in the US and Australia (December 2021–March 2025).
• Participants and intervention: Of 1,811 randomized patients, 1,000 received platelet transfusions. Patients received platelets stored at 1°C–6°C for up to 21 days or at 20°C–24°C for up to 7 days.
• Outcomes: The primary outcome was a 5-level hemostatic efficacy score during the 24 hours after the first transfusion; the secondary outcome was chest tube output at 24 hours.

Key Findings:

• Cold-stored platelets met the prespecified noninferiority criterion at every evaluated storage duration through 21 days; posterior probability exceeded 99.9%.
• The pooled mean hemostatic efficacy score was 3.08 with cold-stored platelets and 2.99 with room-temperature platelets (estimated difference, 0.09 points); no storage duration showed superiority.
• Chest tube output did not differ significantly: median 8.9 mL/kg with cold-stored platelets versus 8.4 mL/kg with room-temperature platelets.
• Reexploration for bleeding within 24 hours occurred in 4.2% versus 1.8%, respectively. Cold-stored platelet recipients also received greater volumes of blood products at 24 and 72 hours.
• Exploratory safety analyses found no statistically significant between-group differences in thrombotic events, other reported adverse events, or 28-day mortality.

Interpretation:

The authors reported noninferior hemostatic efficacy with cold-stored platelets through 21 days, while noting higher reexploration rates and blood product use in the cold-stored group. They described extended cold storage as a potential way to reduce platelet shortages and waste, particularly where conventional inventories cannot be maintained.

Limitations:

• Platelet transfusion indications and thresholds for blood components and other interventions were not standardized.
• Some patients received both platelet types because of protocol deviations and inventory limitations, which may have favored noninferiority.
• The modified hemostatic efficacy score for patients weighing 50 kg or less had not been validated.
• The authors advised interpreting findings in the context of existing platelet transfusion practices in complex cardiac surgery.

Sources:

• JAMA