Chew DP, Lambrakis K, Blyth A, et al. A Randomized Trial of a 1-Hour Troponin T Protocol in Suspected Acute Coronary Syndromes: The Rapid Assessment of Possible Acute Coronary Syndrome in the Emergency Department With High-Sensitivity Troponin T Study (RAPID-TnT). Circulation. 2019 Nov 5;140(19):1543-1556. doi: 10.1161/CIRCULATIONAHA.119.042891. Epub 2019 Sep 3. (Original study)

BACKGROUND: High-sensitivity troponin assays promise earlier discrimination of myocardial infarction. Yet, the benefits and harms of this improved discriminatory performance when incorporated within rapid testing protocols, with respect to subsequent testing and clinical events, has not been evaluated in an in-practice patient-level randomized study. This multicenter study evaluated the noninferiority of a 0/1-hour high-sensitivity cardiac troponin T (hs-cTnT) protocol in comparison with a 0/3-hour masked hs-cTnT protocol in patients with suspected acute coronary syndrome presenting to the emergency department (ED).

METHODS: Patients were randomly assigned to either a 0/1-hour hs-cTnT protocol (reported to the limit of detection [<5 ng/L]) or masked hs-cTnT reported to =29 ng/L evaluated at 0/3-hours (standard arm). The 30-day primary end point was all-cause death and myocardial infarction. Noninferiority was defined as an absolute margin of 0.5% determined by Poisson regression.

RESULTS: In total, 3378 participants with an emergency presentation were randomly assigned between August 2015 and April 2019. Ninety participants were deemed ineligible or withdrew consent. The remaining participants received care guided either by the 0/1-hour hs-cTnT protocol (n=1646) or the 0/3-hour standard masked hs-cTnT protocol (n=1642) and were followed for 30 days. Median age was 59 (49-70) years, and 47% were female. Participants in the 0/1-hour arm were more likely to be discharged from the ED (0/1-hour arm: 45.1% versus standard arm: 32.3%, P<0.001) and median ED length of stay was shorter (0/1-hour arm: 4.6 [interquartile range, 3.4-6.4] hours versus standard arm: 5.6 (interquartile range, 4.0-7.1) hours, P<0.001). Those randomly assigned to the 0/1-hour protocol were less likely to undergo functional cardiac testing (0/1-hour arm: 7.5% versus standard arm: 11.0%, P<0.001). The 0/1-hour hs-cTnT protocol was not inferior to standard care (0/1-hour arm: 17/1646 [1.0%] versus 16/1642 [1.0%]; incidence rate ratio, 1.06 [ 0.53-2.11], noninferiority P value=0.006, superiority P value=0.867), although an increase in myocardial injury was observed. Among patients discharged from ED, the 0/1-hour protocol had a negative predictive value of 99.6% (95% CI, 99.0-99.9%) for 30-day death or myocardial infarction.

CONCLUSIONS: This in-practice evaluation of a 0/1-hour hs-cTnT protocol embedded in ED care enabled more rapid discharge of patients with suspected acute coronary syndrome. Improving short-term outcomes among patients with newly recognized troponin T elevation will require an evolution in management strategies for these patients.

CLINICAL TRIAL REGISTRATION: URL: https://www.anzctr.org.au. Unique identifier: ACTRN12615001379505.

Discipline Area Score
Emergency Medicine 6 / 7
Internal Medicine 6 / 7
Cardiology 6 / 7
Public Health 6 / 7
Comments from MORE raters

Cardiology rater

This is useful information for house staff, internists, and ER physicians. A large study. Interesting if a 2-hr window for high-sensitivity troponin were studied, it may be the sweet spot to reduce unnecessary invasive strategy and allow for safe early discharge. Although 30-day outcomes show no difference between the 2 arms, 180- and 365-day outcomes may also be of interest to assess.

Emergency Medicine rater

I`m an ED doc in a high-volume shop, so I am interested in rapid patient turnover. This is a good early study but does it change practice in a specialty that depends on the HEART score? No, it does not...yet.

Emergency Medicine rater

Nice validation of the 0/1 rule using 5th-generation troponin T that can reduce ED LOS and decrease testing without increasing harm (compared with 0/3 rule-out). Readers, however, will need to understand the protocol that is used (delta troponins for rule-in, rule-out, indeterminate), as this will be new to most (and is not intuitive and will likely lead to errors in implementation).

Internal Medicine rater

The study provides very useful information for rapid clinical decision-making to discharge low-risk patients with suspected ACS from the ED with reduced median ED length-of-stay, high negative-predictive value for 30-day death and MI (99.6%) with inherent limitations of early termination of the study.

Public Health rater

Interesting study but uncertain that the results are transportable to different healthcare settings.
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