Results from the RAPID-TnT (the Rapid Assessment of Possible ACS In the emergency Department with high sensitivity Troponin T) Study presented Tuesday by Derek P. Chew, MBBS, MPH, PhD, at the European Society of Cardiology Congress 2019 demonstrated that the evaluation of a 0- to 1-hour high sensitivity cardiac troponin (hs-cTnT) protocol enabled more rapid discharge from the emergency department (ED) of patients suspected of acute coronary syndrome (ACS) and was associated with a very low rate of 30-day death or myocardial infarction in comparison with compared with 0- to 3-hour masked hs-cTnT.
In addition, in patients with low levels of troponin concentrations, invasive management was increased with a greater rate of myocardial injury and infarction, the results showed.
It has been demonstrated that the use of hs-cTnT assays promise earlier detection of myocardial infarction. However, it is still not clear how this rapid testing impacts subsequent cardiac testing (i.e., non-invasive versus invasive modalities) and clinical events. RAPID-TnT (funded by Roche Diagnostics) sought to clarify this question.
The trial was a multicenter, patient-level, randomized non-inferiority study evaluating 0- to 1-hour hs-cTnT protocol compared with a 0- to 3-hour masked hs-cTnT protocol in patients with suspected ACS presenting to the emergency department. The study enrolled a total of 3288 patients, 1646 in the 0/1-hour hs-cTnT arm and 1642 in the standard 0/3-hour arm. The primary outcome for the trial was death or myocardial infarction within 30 days.
Results demonstrated that the 0/1-hour arm participants were more frequently discharged from the ED (45.1% versus 32.3% in the standard arm, p<0.001) with an associated shorter median emergency department length of stay (4.6 hours versus 5.6 hours, p<0.001). In addition, the 0/1-hour protocol patients were less likely to undergo functional cardiac testing (7.5% versus standard arm, 11.0%; p<0.001). More importantly, discharge with a rule-out myocardial infarction recommendation was associated with a 0.3% (95% confidence interval [CI] 0.02-0.06) rate of death or myocardial infarction within 30 days, yielding a negative predictive value of 99.6% (95% CI 99.0% to 99.9%, specificity 73.2%).
The study supports the use a 0/1-hour hs-cTnT protocol for early rule-out of patients with suspected ACS and that those patients are safe for early discharge with an acceptably low rate of death or myocardial infarction within 30 days. However, the protocol does not appear to improve the diagnosis of myocardial infarction, and invasive coronary investigation is increased among patients with low-concentration troponin elevations. Future strategies are needed to refine ACS care.