A testing protocol using rapid, high-sensitivity cardiac troponin T (hs-cTnT) did not reduce death or myocardial infarction (MI) at one year in patients with suspected acute coronary syndrome (ACS) without ischemia on the initial ECG, according to results from the RAPID-TnT trial presented May 16 during ACC.21 and simultaneously published in Circulation.

Derek Chew, MBBS, MPH, PhD, FACC, et al., randomized 3,378 patients (median age, 58 years; 53% male) with suspected ACS in the emergency department at four metropolitan centers in South Australia to standard care (hs-cTnT test at hour 0 and hour 3, with masked result) or to the intervention (hs-cTnT at hour 0 and hour 1). For the standard care group, the treating physicians were blinded to test results below 29 ng/L, in accordance with standards of practice at the time, and subsequent care was at the treating physician's discretion. For the intervention group, in which the hs-cTnT was reported to a level as low as 5 ng/L, physicians categorized patients as rule in (treat as ACS), rule out (ACS probability <1%) or further observation (ACS probability 25%).

The results showed that for 92% of the 3,270 patients available for analysis, both of their troponin T tests was below 29 ng/L. Patients in the intervention group were discharged earlier and underwent less functional stress testing, but had more coronary angiography and revascularization.

The primary endpoint of MI adjudicated using the Fourth Universal Definition of MI or all-cause death at 12 months occurred in 5% of the intervention group and 3.8% of the standard care group (hazard ratio [HR], 1.32; 95% confidence interval, 0.95-1.83; p=0.10). Of note, in patients with an initial troponin T level ≤29ng/L, unmasked hs-cTnT reporting was associated with an increase in primary endpoint events (3.7% vs. 2.3% in the intervention and standard care groups; HR, 1.60; p=0.030).

"This finding may imply that the practice changes observed with the use of a zero/one-hour, high-sensitivity troponin T testing protocol – fewer stress tests and slightly more angiograms – may be associated with an increase in the risk of death or a heart attack within 12 months," says Chew. "However, it is possible that this finding occurred by chance, and therefore it should be interpreted with caution. Overall, the finding may signal the continued utility of functional testing, such as stress tests, and a need for reconsideration of downstream investigations and therapies in the large presenting population with low-level troponin elevations."

Clinical Topics: Acute Coronary Syndromes, ACS and Cardiac Biomarkers

Keywords: ACC Annual Scientific Session, ACC21, Acute Coronary Syndrome, Biomarkers, Troponin T

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