TABLE 2.

Clinical Decision Pathways With Hs-cTn

Approach	Criteria for Rule Out	Advantages	Disadvantages
0/3 h	Single hs-cTn <99th percentile URL if symptoms >6 h and now pain free OR If <6 h of symptoms, 0- and 3-h troponin less than the 99th percentile URL	Uses 99th percentile URL cutoffs similar to conventional troponin, which is familiar to clinicians Conceptually simpler Validated	Lower sensitivity and NPV, and fewer patients ruled out compared with other pathways
0-h (single draw)	0-h rule out for cTn below LoQ or an optimized cutoff (eg, hs-cTnI <5 ng/L)	Immediate rule out of low-risk patients Takes advantage of sensitivity of hs-cTn	Applies to <50% of patients Not suitable for patients presenting early
0/1-h rule out	Use baseline (0-h) and delta values at 1 h to assign patients to the rule-out, observation, or abnormal groups	Takes advantage of better assay sensitivity and precision Avoids inherent problems with 99th percentile URL value Rules out a large proportion of patients	Complex algorithm Timing of blood draws very important May miss late-presenting MI on the “flat” portion of a declining troponin trend
0/2-h rule out	Identical approach to 0/1-h rule out except delta assessed at 2 h	Takes advantage of higher sensitivity and precision of assay More practical for some centers that cannot routinely obtain 1-h samples Better for early presenters than 0/1-h algorithm	Longer time to rule out than 0/1-h algorithm Equally complex as 0/1-h algorithm May miss late-presenting MI on the “flat” portion of a declining troponin trend Not validated in RCTs
High-STEACS	MI is ruled out if initial hs-cTnI <5 ng/L or hs-cTnT <6 ng/L (if >3 h from symptom onset) or if change from initial to 3-h hs-cTn is <3 ng/L and remains below sex-specific 99th percentile URL	Takes advantage of better sensitivity and precision of assay Safety and efficacy validated in randomized controlled trial61 High rates of safe rule out Uses sex-specific 99th percentile cutpoint	Longer time to rule out for patients with initial hs-cTnI ≥5 ng/L or hs-cTnT ≥6 ng/L Fewer patients discharged from ED than with 0/1- or 0/2-h algorithms

ED = emergency department; High-STEACS = High-Sensitivity Troponin in the Evaluation of Patients with Acute Coronary Syndrome; hs-cTn = high-sensitivity cardiac troponin; hs-cTnI = high-sensitivity cardiac troponin I; hs-cTnT = high-sensitivity cardiac troponin T; LoQ = limit of quantification; MI = myocardial infarction; NPV = negative predictive value; RCT = randomized controlled trial; URL = upper reference limit.