Introduction and methods

The Late Outcomes Of A 1-hour High Sensitivity Troponin T Protocol in Suspected Acute Coronary Syndromes: A Randomized Clinical Trial

Presented at ACC.21 by Derek Chew , MD, PhD (Adelaide, Australia)

In patients with suspected ACS who present at the emergency department (ED), high-sensitivity (hs) troponin (TnT) assays, together with early ED workup, can rule-out ACS with good diagnostic certainty. Impact on late-outcomes of subsequent changes in ‘down-stream testing’ and therefore changes in acute care practices has not been examined in RCTs.

In 2011, the 5th generation assay became available with an improved sensitivity and lower detection of troponin. This assay has been deployed but results below the previous reporting range (<29 ng/L) were masked to the clinicians. In this study, unmasking of troponin was studied in a randomized, patient-level study. A previous analysis of this study showed non-inferiority of care informed by the 0-1 hour hs-cTnT rule out at 30 days and a negative predictive value for death or MI at 30 days of 99.6%.

In this analysis, the effectiveness of care informed by 0-1 hour hs-cTnT unmasking reporting compared to standard 0-3 hour protocol on the composite of all-cause death or MI at 12 months was examined. This was analyzed in all patients and in a subgroup of patients with an initial troponin ≤29 ng/L.

The RAPID TnT trial enrolled 3378 patients with suspected ACS who were randomized to the 0-1 hr hs-cTnT protocol (n=1689) or the standard 0-3 hr protocol (n=1689). 91% Of patients in the standard care group had a hs-cTnT levels in the masked range (≤29 ng/L) and 92% of patients in the 0-1 hr hs-cTnT protocol group.

Main results

• There was a non-significant increase in the rate of the primary endpoint at 12 months for the 0-1 hour unmasked hs-cTnT group compared to the 0-3 hour masked hs-cTnT group (5.01% vs. 3.8%, respectively, HR 1.32, 95%CI: 0.95-1.83, P=0.10).
• When looking at patients with troponin ≤29 ng/L, there was an increase in the primary endpoint for patients in the 0-1 hour unmasked hs-cTnT group compared to the standard care group after 12 months (3.7% vs. 2.3%, respectively, aHR 1.63, 95%CI:1.15-2.30, P=0.006).
• There was no difference for CV re-hospitalization (non-coronary) at 12 months between the two groups, in the total population and in the subgroup of patients with troponin ≤29 ng/L.
• Total number of events for type 1 MI and unstable angina were higher in the 0-1 hour unmasked hs-cTnT group than in the 0-3 hour masked hs-cTnT group, in the total population and the subgroup of patients with troponin ≤29 ng/L.
• A significant lower rate of functional testing within 30 days was found for patients in the 0-1 hour hs-cTnt protocol group compared to the standard care group, when looking at all patients and in the subgroup of patients with troponin ≤29 ng/L. But a higher percentage of patients in the 0-1 hour hs-cTnt protocol underwent coronary angiogram or coronary revascularization, in the total population and in the subgroup.

Conclusion

The rapid (0-1 hour) unmasked hs-TnT protocol was not associated with a decrease in the composite of all-cause death or MI after follow-up of 12 months. In patients with troponin level ≤29 ng/L, the rapid unmasked protocol was associated with an increase in the primary endpoint of all-cause death and MI. Furthermore, the randomized allocation to unmasked hs-cTnT within 0-1 hour protocol was associated with a reduction in functional testing and an increase in coronary angiography and revascularization.

Discussion

The discussant Deepak Bhatt (Boston, MA, USA) said that these results will likely not lead to direct changes in clinical practice, but they highlight some issues in the field. One of the issues is that EDs struggle with the large number of patients with presentation of chest pain. So there is a lot of research on the question what to do with the patient with chest pain at the ED. Besides ECG, troponin testing can provide useful information. In this study however it was not clear whether early testing of troponin improves outcomes. There was even a signal that it worsens outcomes, but that may be due to the actions taken (or not taken) based on the troponin testing strategy. This study highlighted that at the low but abnormal levels of troponin, it is not so clear what to do with these patients. Furthermore, this study points to the need for more research, according to prof Bhatt.

- Our coverage of ACC.21 is based on the information provided during the congress –

Watch a video on this study by prof. Chew The findings of this study were simultaneously published in Circulation