The ESC 0/2h-hs-cTn-algorithms have higher efficacy and comparable safety versus the ESC 0/1h-hs-cTn-algorithms in patients with prior coronary artery bypass grafting.
Key Findings
Results
The ESC 0/2h-hs-cTn-algorithms demonstrated higher efficacy than the 0/1h-algorithms in patients with prior coronary artery bypass grafting.
Efficacy (proportion of patients triaged to rule-in or rule-out) was 50.6% for 0/1h and 58.4% for 0/2h using hs-cTnT-Elecsys, a difference of 7.9% (95% CI 4.2–11.5).
Higher efficacy for 0/2h versus 0/1h was confirmed using hs-cTnI-Architect with a difference of 3.1% (95% CI 0.1–6.1).
External validation using hs-cTnI-Atellica in an independent US multicenter cohort (n=178) showed a difference in efficacy of 9% (95% CI 4.5–13.5) in favor of 0/2h.
The study included 356 patients with median age 73 (IQR 64–80) years and NSTEMI prevalence of 31% (n=112).
Results
Sensitivity for rule-out of NSTEMI was high and comparable between the 0/1h- and 0/2h-hs-cTnT-Elecsys algorithms in prior CABG patients.
Sensitivity for rule-out was 100% (95% CI 96.7–100) for the ESC 0/1h-hs-cTnT-Elecsys algorithm.
Sensitivity for rule-out was 99.1% (95% CI 95.1–99.8) for the ESC 0/2h-hs-cTnT-Elecsys algorithm.
Safety (high sensitivity for rule-out) was described as comparable between the two algorithms.
Final diagnoses were centrally adjudicated according to the Universal Definition of Myocardial Infarction.
Results
Specificity for rule-in of NSTEMI was high and slightly higher for the 0/2h versus the 0/1h algorithm using hs-cTnT-Elecsys.
Specificity for rule-in was 97.1% (95% CI 94.2–98.6) for the 0/1h-hs-cTnT-Elecsys algorithm.
Specificity for rule-in was 98.4% (95% CI 95.9–99.4) for the 0/2h-hs-cTnT-Elecsys algorithm.
Assay-specific use-optimized cut-offs were applied for both algorithms.
Findings were consistent across multiple assays (hs-cTnT-Elecsys, hs-cTnI-Architect, hs-cTnI-Atellica).
Methods
The study was a prospective international multicenter diagnostic study with external validation in an independent US multicenter cohort.
The primary cohort included 356 patients with prior coronary artery bypass grafting presenting to the emergency department with acute chest discomfort.
The external validation cohort comprised 178 patients from an independent prospective US multicenter study.
The study was registered at ClinicalTrials.gov (NCT00470587).
The hypothesis was that the longer time to second blood draw in the 0/2h-algorithm would increase efficacy compared to the 0/1h-algorithm in these high-risk patients.
Background
The ESC 0/1h-hs-cTn algorithms were previously known to have lower efficacy in patients with prior coronary artery bypass grafting.
Prior coronary artery bypass grafting is characterized as a high-risk patient population for reduced algorithm efficacy.
The study was motivated by the known limitation of the 0/1h-algorithm in this subgroup.
The longer time to the second blood draw in the 0/2h-algorithm was hypothesized to compensate for this limitation by allowing greater troponin kinetics to be captured.
The median age of the study population was 73 years (IQR 64–80), reflecting the typically older, high-risk nature of CABG patients.
What This Means
This research studied two different blood test timing strategies used in emergency departments to quickly determine whether a patient is having a heart attack. Both strategies measure a heart protein called high-sensitivity cardiac troponin (hs-cTn), but they differ in when the second blood sample is taken — either 1 hour or 2 hours after the first. The study focused specifically on patients who had previously undergone coronary artery bypass grafting (CABG), a type of open-heart surgery, because prior research showed the 1-hour strategy was less effective in this group. The study enrolled 356 such patients across multiple international sites, with about 31% ultimately diagnosed with a heart attack (NSTEMI).
The findings showed that both timing strategies were very safe — meaning they rarely missed a true heart attack — but the 2-hour strategy was better at classifying more patients into either a 'rule-in' or 'rule-out' category, leaving fewer patients in an uncertain 'observe' zone. Specifically, the 2-hour algorithm triaged about 58% of patients compared to about 51% for the 1-hour algorithm, a statistically significant difference. These results were consistent across three different troponin assay types and were confirmed in an independent U.S. validation cohort of 178 patients.
This research suggests that in patients with a history of bypass surgery, using the 2-hour blood draw strategy may allow emergency physicians to make faster, more definitive decisions about whether a patient needs to be admitted or can be safely discharged, without sacrificing safety. This could improve patient flow in emergency departments and reduce unnecessary hospital stays for this high-risk patient population.
Koechlin L, Boeddinghaus J, Lopez-Ayala P, Jacobsen G, McCord J, Heimbach B, et al.. (2026). Direct Comparison of the 0/1h- and 0/2h-Algorithms in Patients With Prior Coronary Artery Bypass Grafting.. Journal of the American Heart Association. https://doi.org/10.1161/JAHA.125.046718