Key result
Six-year serum storage at -80°C yields substantially better hs-cTnT clinical performance than heparin plasma.
Why the study?
As high-sensitivity cardiac troponin T transitions from diagnostic to prognostic use, long-term stability data for 5th generation hs-cTnT in frozen clinical specimens across different matrices were needed.
Does long-term storage at -80 °C affect the stability and clinical performance of hs-cTnT measured in serum versus lithium heparin plasma?
Observational (n=86)
Does long-term storage at -80 °C affect the stability and clinical performance of hs-cTnT measured in serum versus lithium heparin plasma?
Absolute Event Rate: 105.4% vs 106.2%
Serum is superior to lithium heparin plasma for long-term storage at -80 °C when evaluating absolute delta increments of hs-cTnT around clinical decision points.
Serum may be preferred for archived hs-cTnT samples in delta analyses; leaves open prospective validation before practice change.
OBJECTIVES: As high-sensitivity cardiac troponin T (hs-cTnT) is making the transition from diagnostic to prognostic use, a long-term stability study of 5th generation hs-cTnT according to EFLM CRESS recommendations was set up for investigation of frozen clinical specimens (two matrices). METHODS: Study samples collected in serum tubes and lithium heparin tubes with gel from patients admitted for suspected minor myocardial damage were measured directly after completion of the study (0 years), and after 3-year and 6-year storage at -80 °C, and recovery of hs-cTnT concentrations after long-term storage (%hs-cTnT concentration compared to 0-year) was calculated. Hs-cTnT changes were also compared to decisive delta changes, such as the ones proposed in the ESC NSTEMI 0 h/1 h algorithm (<3 or >5 ng/L for ruling out and ruling in suspected NSTEMI patients). RESULTS: Eighty-six patients were included in the study, whereof 28 both lithium heparin plasma and serum samples were collected simultaneously, in others only serum (n=30) or plasma (n=28). Multiple aliquots per patient were made, so that 479 serum and 473 plasma samples were available for analysis. Across the overall hs-cTnT measuring range, median recovery after 6 years was 105.4 % and 106.2 % for serum and plasma, respectively. Based on these decisive delta changes, serum showed consistent results upon long term storage (max 0.8 % of samples above delta threshold of >5 ng/L) as compared to heparin plasma (up to 19.2 % of samples above threshold). CONCLUSIONS: Over 6 years of storage at -80 °C, recovery of hs-cTnT in serum and heparin plasma was similar and within common lot-to-lot variation. Yet, when evaluating absolute delta increments around hs-cTnT clinical decision points, long-term stored sera displayed better clinical performance compared to heparin plasma samples.
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Henricks et al. (2024) conducted an observational in Suspected minor myocardial damage (n=86). Serum samples vs. Lithium heparin plasma samples was evaluated on Recovery of hs-cTnT concentrations after long-term storage. Long-term storage of serum at -80 °C for 6 years yielded better clinical performance for hs-cTnT delta increments compared to heparin plasma (max 0.8% vs up to 19.2% above the >5 ng/L threshold).
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