PROACT-4 Trial on Benefits of Troponin Testing for Acute Cardiovascular Disease

Chest pain is one of the most common reasons that patients visit the emergency room, and the use of troponin testing can help cut down the time between first medical contact to final patient disposition.

In 2014, the PROACT-3 trial analyzed pre-hospital point-of-care using troponin testing — a system that assesses the proteins troponin I and troponin T in the heart in order to diagnose cardiovascular events. The results from the study did not show a difference in the primary outcome. Therefore, Justin A. Ezekowitz, from the University of Alberta, and colleagues reworked the trial to create PROACT-4. The findings were revealed during a presentation at the American Heart Association 2015 Scientific Sessions (AHA 2015) in Orlando, Florida.

Troponin is a standard biomarker for assessing chest pain, Ezekowitz began his talk at AHA 2015. Using patients suspected of having acute coronary syndrome, the primary outcome was to find the amount of time between the first medical contact (after 911 dispatchers arrive on the scene) to when they are released from care and how to facilitate a shorter time between these two points.

Nearly 600 patients, with an average age of 65 and about 40% female, participated in PROACT-4. Patients got tested in the ambulance with a point-of-care device and gave verbal consent to be included in point-of-care troponin. A total of 292 patients opted for usual care and 305 went with troponin. Usual care was available after an average of 138 minutes while point-of-care troponin began in 38 minutes.

The researchers believed that there was “90% power for 25% reduction (120-minute) in time to ED final disposition in [point-of-care troponin] group with 600 pnts and 10% failure.” Note that a 60-minute reduction in care would be ‘clinically relevant.’

The time from first medical contact to disposition was 8.8 hours in the troponin group and 9.1 hours in usual care group. What’s interesting here is that it took 138 minutes to get the first usual care and 38 minutes to get troponin from the first medical contact, but the final disposition time only differed by about 20 minutes.

The results revealed that troponin had 44% specificity and 96% sensitivity. About 70% of the patients with chest pain had a final diagnosis that was non-cardiac. However, 112 of them had acute coronary syndrome.

“There was no differences in clinical endpoints in the next three days,” Ezekowitz explained of the secondary outcome.

The discussant of the session brought up some questions that still linger. The troponin test had an 18% failure rate and 38-minute turnaround time — so is there something better out there? Also, the test’s 44% sensitivity is modest so it presents the challenge of integrating advanced diagnostic protocols. Finally, the disposition time is still close to nine hours – are there opportunities to create a system to shorten down this time? The discussant also pointed out that tools like these are already available, but PROACT-4 was able to put them in a pragmatic design to execute real-world results.

Reducing the time between first medical contact to patient disposition has the potent to reduce emergency room crowding and care costs.

Ezekowitz ended his presentation by announcing that the study has been accepted by the Journal of the American Heart Association and will soon be published online.