Ischemic events among individuals with suspected acute coronary syndrome (ACS) were not reduced over a 12-month follow-up when using unmasked 0/1-hour high-sensitivity cardiac troponin T (hs-cTnT) protocol, according to a multicenter prospective randomized study published in Circulation.
Between August 2015 and April 2019, researchers enrolled participants in the study, who had presented to metropolitan emergency departments with suspected ACS and without electrocardiographic evidence of coronary ischemia. Study participants were randomly assigned to an unmasked 0/1-hour hs-cTnT protocol and a masked 0/3-hour hs-cTnT protocol. Follow-up lasted 12 months.
Primary endpoints included myocardial infarction (MI) or all-cause mortality. Cox proportional hazards models were used to adjust for clustering within medical facilities. Secondary endpoints included individual components of the primary endpoint; peripheral vascular revascularization, unstable angina, and cerebrovascular accidents; congestive cardiac failure, and atrial and ventricular arrhythmias; and bleeding events in the 12 months after randomization classified by the Bleeding Academic Research Consortium criteria.
Among the study participants, 91.5% had an initial troponin concentration within the masked range (≤29 ng/L). Those in the 0/1-hour unmasked hs-cTnT group, compared with the 0/3-hour arm, were discharged earlier (median length of hospitalization 3.8 vs 4.2 hours; P <.001) and more frequently (45.0% vs 32.3%; P <.001). The 0/1-hour unmasked arm also had a lower rate of functional testing. No differences were observed in invasive coronary angiography between the 0/1-hour and 0/3-hour groups (14.2% vs 12.4%; P =.13), though frequency was higher among those in the unmasked range of hs-cTnT levels (11.2% vs 8.3%; P =.010).
The study arms, 0/1-hour vs 0/3-hour, did not differ in terms of all-cause mortality and MI by 12 months (5.0% vs 3.8%; hazard ratio [HR], 1.32; 95% CI, 0.95-1.83; P =.10). For those with initial troponin T concentrations less than or equal to 29 ng/L, the use of unmasked hs-cTnT reporting correlated with increased mortality or MI (3.6% vs 2.3%; HR, 1.60; 95% CI, 1.05-2.46; P =.030).
Limitations to this study include a potential for fewer investigations and representations due to masking, potential type 1 error among observations within the masked range, and a focus on individuals less likely to evolve ACS at initial presentation.
“Translating improvements in the performance of high-sensitivity troponin assays into improvements in patient outcomes may require reconsideration of the downstream investigative and therapeutic strategies,” the study authors noted. “Recognition of the persistent risk associated with modest troponin elevations among the many patients with presentations not attributable to type 1 MI represents an opportunity to explore strategies to impact future cardiovascular events.”
Disclosure: This clinical trial was supported by Roche Diagnostics International. Please see the original reference for a full list of authors’ disclosures.
Lambrakis K, Papendick C, French JK, et al. Late outcomes of the RAPID-TnT randomized controlled trial: 0/1-hour high-sensitivity troponin T protocol in suspected ACS. Circulation. 2021;144(2):113-125.doi: 10.1161/CIRCULATIONAHA.121.055009