Cardiac troponin test refines ACS rule-out process

By Eleanor McDermid

Testing high-sensitivity cardiac troponin T (hs-cTnT) levels in patients with acute coronary syndromes (ACS) reduces their need for cardiac stress testing and speeds their discharge from the emergency department, report researchers.

And the introduction of hs-cTnT testing did not result in the "increased or inappropriate use of coronary angiography", Christian Mueller (University Hospital Basel, Switzerland) and study co-authors report in the European Heart Journal.

In their multicentre study, 29% of 1455 patients treated in three hospitals before the introduction of hs-cTnT testing underwent stress testing, compared with just 19% of 1089 patients treated after its introduction.

"This reduction was seen exclusively in the rate of exercise [electrocardiography], the stress modality that is usually applied in low-to-moderate risk patients", note the researchers. Rates of this test fell from 17% to 9%.

At the same time, the median duration of stay in the emergency department fell by 72 minutes, from 377 to 305 minutes. Over the same period, the use of stress testing remained stable in another three hospitals that did not introduce hs-cTnT testing, and the median time to discharge increased by 97 minutes.

Mueller and team say the improvements in the hospitals that introduced hs-cTnT testing are "even more impressive" when considering the "learning phase" that was necessary after its introduction.

There was an educational campaign accompanying the change, and at the same time the diagnostic cutoff for acute myocardial infarction was reduced to the 99th percentile, as per the European Society of Cardiology guidelines.

The rates of coronary angiography and percutaneous coronary intervention remained identical in both periods, at 23% and 13%, respectively.

Introduction of hs-cTnT testing had no major influence on the management of patients eventually diagnosed with acute myocardial infarction; there was a slight increase in the proportion of coronary angiographies (81 vs 90%) and length of observation (217 vs 289 min). But among patients with other diagnoses, the use of stress testing fell from 30% to 20% and the observation time fell from 390 to 310 minutes.

"High-sensitivity cardiac troponin T was associated with an improved rule-out process and thereby helped to substantially reduce the need for cardiac stress testing and time to discharge", concludes the team.

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