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RAPID-TnT: High-sensitivity troponin assay enables faster discharge in suspected ACS
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PARIS — A 1-hour protocol including a high-sensitivity troponin T assay was associated with faster discharge of patients with suspected ACS compared with a 3-hour protocol, and it was noninferior in terms of clinical outcomes, researchers reported at the European Society of Cardiology Congress.
For the RAPID-TnT study, the researchers randomly assigned 3,288 participants (median age, 59 years; 48% women) presenting to the ED between August 2015 and April 2019 to care guided by a 1-hour protocol with a high-sensitivity troponin T assay (Elecsys, Roche Diagnostics) or to care guided by a 3-hour protocol.
The primary endpoint was death or MI at 30 days. The results were simultaneously published in Circulation.
“What we wanted to know is what was the clinical impact of the improved diagnostic precision of high-sensitivity troponin T when incorporated into a zero-and-1-hour protocol in terms of patient outcomes and/or greater efficiency in the emergency department when embedded in clinical practice,” Derek P. Chew, MBBS, MPH, PhD, professor of cardiology at the College of Medicine and Public Health, Flinders University of South Australia and regional director of cardiology for Adelaide Health Service, both in Adelaide, Australia, said during a presentation.
Patients with STEMI were excluded, as were patients with a clear alternative explanation for their chest pain, he said.
In the standard 3-hour protocol, “patients with a troponin level greater than 29 ng/L on any sample or prior coronary artery disease or ongoing chest pain were recommended for admission,” Chew said during the presentation. “Patients with a troponin level less than or equal to 29 ng/L and no ongoing chest pain were then risk-stratified by their coronary risk factors and their age, and a discussion was often held and a decision made for early outpatient functional testing, early inpatient functional testing or discharge back to primary care.”
The 1-hour protocol, he said, was based on two blood draws in accordance with ESC guidelines. “Patients with substantial elevations in troponin were recommended for admission, those with intermediate levels were recommended for greater observation and we informed the clinicians of their likelihood of ACS, and those with very low-level troponin concentrations detected with low probability of ACS had a decision about their care made by the clinicians.”
Participants in the 1-hour group were more likely to be discharged without being admitted than those in the 3-hour group (45.1% vs. 32.3%; P < .001) and had a shorter median length of stay in the ED (4.6 hours vs. 5.6 hours; P < .001), Chew said.
The 1-hour group was less likely to undergo functional cardiac testing than the 3-hour group (7.5% vs. 11%; P < .001), according to the researchers.
In the standard protocol, 33.4% of patients were recommended for admission and the rest were recommended for discharge, whereas in the 1-hour protocol, 8.3% were ruled in for MI and admitted, 18.7% were admitted for further observation and 72.1% were ruled out for MI and recommended for discharge, Chew said.
At 30 days, death or MI occurred in 1% of both groups (incidence rate ratio [IRR] = 1.06; 95% CI, 0.53-2.11; P for noninferiority = .006), according to the researchers.
Among the 1-hour protocol cohort, those discharged from the ED had a 99.6% negative predictive value (95% CI, 99-99.9) for 30-day MI or death, Chew said.
However, CV rehospitalization, defined as rehospitalization for nonelective coronary revascularization, HF, cerebrovascular accident or arrhythmias, at 30 days was somewhat higher in the 1-hour group (IRR = 1.53; 95% CI, 1.12-2.1), and the 1-hour group had more cases of MI or myocardial injury (1.6% vs. 1%; P = .004), Chew and colleagues found.
“Patients ruled out under the 1-hour protocol appeared to be safe for early discharge,” Chew said during the presentation. “This would support the routine implementation of the zero-and-1-hour protocol.” – by Erik Swain
References:
Chew DP, et al. Hot Line Session 6. Presented at: European Society of Cardiology Congress; Aug. 31-Sept. 4, 2019; Paris.
Chew DP, et al. Circulation. 2019;doi:10.1161/CIRCULATIONAHA.119.042891.
Disclosure: The study was funded in part by an unrestricted educational grant from Roche Diagnostics. Chew reports he received grants-in-aid from Roche Diagnostics.