Quicker diagnosis protocol for suspected ACS fails to improve outcomes

Discharging patients with suspected acute coronary syndrome (ACS) under a 0- and 1-hour high-sensitivity cardiac troponin T (hs-cTnT) protocol is helpful for clearing waiting rooms, according to work presented at the ESC Congress Sept. 3, but the streamlined process remains noninferior to a 0/3-hour protocol.

Principal investigator and professor Derek Chew, of Flinders University in Adelaide, Australia, said at the Paris conference that his team’s findings also suggest we need better strategies for optimizing outcomes in patients with newly diagnosed troponin elevations. European Society of Cardiology guidelines recommend a 0/1-hour hs-cTnT protocol for patients with suspected non-ST segment elevation MI (NSTEMI) to speed up discharge and treatment processes, but evidence backing that approach is limited to observational studies.

Chew explained that NSTEMI can be ruled out at presentation if a patient’s hs-cTnT levels are very low, or if baseline levels are somewhat low and don’t increase within an hour of presenting to the hospital. Moderately elevated troponin or hs-cTnT concentrations that rise during the first hour are both major predictors of NSTEMI.

Chew’s team randomly allocated 3,288 patients with suspected ACS to guideline-recommended 0/1-hour hs-cTnT protocol or a more lax 0/3-hour troponin protocol. They found 0/1-hour protocol was noninferior in the population with respect to the study’s primary endpoint of death or heart attack at 30 days.

The 0/1-hour method was linked to less stress testing but more angiography and revascularization, Chew reported. Still, compared to the 0/3-hour cohort, patients in the 0/1-hour arm were less likely to be admitted to the hospital (45.5% vs. 33.2%, respectively), and had shorter lengths of stay (5.6 hours vs. 4.6 hours, respectively).

“Use of a 0/1-hour protocol for discharge is safe, since patients receiving a ‘rule-out’ recommendation had a low rate of events by 30 days (less than 1%),” Chew said in a statement. “In patients recommended for further observation, or ‘rule-in,’ there were more investigations and revascularization associated with more acute myocardial injury or myocardial infarction related to these procedures.”

He said the 0/1-hour approach does have some clear benefits, though, including reducing crowding in the emergency department.

“Better strategies for the increased numbers of patients who are ‘ruled in’ with this method will be required if we are to improve overall outcomes,” Chew said. “The 12-month results from this study will help judge the true value of high-sensitivity troponin testing in clinical practice.”