Acute MI Diagnosis: 0/1 Hour Superior to 0/3 Hour Algorithm

clock ticking myocardial infarction rule out
clock ticking myocardial infarction rule out
The 0/1 hour algorithm was superior to the 0/3 hour algorithm for ruling out acute myocardial infarction.

The 0/1 hour (0/1h) algorithm, which assesses baseline high-sensitivity cardiac troponin (hs-cTn) concentrations as well as changes of these concentrations within the first hour of admission, was superior to the 0/3 hour (0/3h) algorithm for “ruling out” acute myocardial infarction (AMI) in patients who presented to the emergency department (ED) with AMI-like symptoms, according to a study published in Circulation.

Compared with the 0/1h algorithm, the 0/3h algorithm relies on a fixed threshold based on the baseline 99th percentile, as well as 3 hours after admission, in addition to fulfillment of a GRACE (Global Registry of Acute Coronary Events) score of <140 and a pain-free status.

In this study, investigators compared the 0/1h and 0/3h algorithms in terms of their negative predictive value (NPV) and negative likelihood ratio (LR) for AMI hs-cTnI. In addition, the researchers compared the 2 protocols for efficacy, measured by the proportion of AMI diagnoses that were ruled out in patients who presented with AMI-suggestive symptoms on ED admission.

A total of 2547 patients with hs-cTnT concentrations were available for analysis. Of these participants, 15% (n=387) had AMI as the final adjudicated diagnosis. In addition, the investigators developed a second cohort of 2197 patients with hs-cTnI, of whom 15% (n=327) had a final AMI diagnosis.

Protocol safety was similar between the algorithms in patients with hs-cTnT: 0/1h (NPV: 99.8% [95% CI, 99.4%-99.9%]; negative LR: 0.01 [95% CI, 0.00-0.03]) and 0/3h (NPV: 99.7% [95% CI, 99.2%-99.9%]; negative LR: 0.02 [95% CI, 0.00-0.05]). Despite no difference in safety, the 0/1h algorithm did demonstrate significantly greater efficacy for ruling out AMI in a greater proportion of patients vs the 0/3 algorithm (60% vs 44%; P <.001).

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In patients with hs-cTnI, the 0/1h algorithm was considered safer than the 0/3h algorithm (NPV: 99.6% [95% CI, 99.1%-99.9%]; negative LR: 0.02 [95% CI, 0.01-0.05] vs NPV: 97.8% [95% CI, 96.%7-98.5%]; negative LR: 0.13 [95% CI, 0.09-0.19]). The 0/1h and 0/3h algorithms, however, were similar in terms of the efficacy outcome (52% vs 51%; P =.507).

Using the 0/1h algorithm can allow “clinical decision making 2 hours earlier compared with the 0/3h algorithm,” which may facilitate reduced “time to discharge and treatment cost in the ED.”


Badertscher P, Boeddinghaus J, Twerenbold R, et al; for the APACE Investigators Direct comparison of the 0/1h and 0/3h algorithms for early rule-out of acute myocardial infarction. Circulation. 2018;137(23):2536-2538.