PROACT-4: Mixed Results With Point-of-Care Troponin Testing in Chest-Pain Patients

November 10, 2015

ORLANDO, FL — Point-of-care troponin testing done by paramedics in the ambulance appears to briefly shorten the time from first medical contact to final disposition—either admittance to the hospital or discharge—in a broad population of patients with chest pain, a new study shows[1].

When paramedics measured troponin levels, the time from first medical contact to final disposition was 8.85 hours. In contrast, the time from first medical contact until final disposition was 9.14 hours in chest-pain patients receiving usual care, that being troponin testing done in the emergency department. This difference—8.85 hours vs 9.14 hours—was not statistically significant in the intention-to-treat analysis.

"To put this into context, the point-of-care troponin testing we were doing reduced [time] only by 23 minutes," lead investigator Dr Justin Ezekowitz (University of Alberta, Edmonton) told heartwire from Medscape. Despite the small reduction in the time spent in the emergency department before a clinical decision was made, he said the point-of-care testing—with the troponin information relayed ahead to the emergency-department staff—has the potential to affect certain healthcare systems.

"For the US, putting this into practice might be a little more difficult, with their fragmented healthcare," said Ezekowitz. "In the Canadian context, it might be very helpful to 'unplug' the ERs in terms of overcrowding. For the rest of the world, particularly some areas that have limited ER capabilities, I think this could be highly valuable."

Dr Justin Ezekowitz

In the US, said Ezekowitz, there are approximately 5.5 million visits to the emergency department for undifferentiated chest pain each year.

Presenting the results of the Providing Rapid Out-of-Hospital Acute Cardiovascular Treatment (PROACT-4) study today during the late-breaking clinical-trials session at the American Heart Association (AHA) 2015 Scientific Sessions, he said the rationale for the study was to determine whether point-of-care troponin testing could reduce the bottleneck of chest-pain patients presenting to and ultimately waiting around the emergency department.

"It's important to remember that patients with chest pain represent a large proportion of patients seen in the emergency department, many presenting by ambulance, and requiring lots of investigation to rule out cardiovascular disease," said Ezekowitz. "The majority of patients have a noncardiac cause for their chest pain."

In PROACT-4, 601 patients were randomized, with 296 allocated to usual care (troponin testing in the emergency department) and 305 allocated to point-of-care troponin testing. Of the 305 patients, 55 were randomized but did not receive the troponin test in the ambulance. Patients were approximately 65 years of age, nearly one-third had a previous MI, and 25% had diabetes. With usual care, the first troponin test was performed in 138 minutes. In the intervention arm, the point-of-care troponin testing was done within 38 minutes of first medical contact.

In the intention-to-treat analysis, despite a nonsignificant reduction in the time from first medical contact to final disposition, investigators did observe a small, but statistically significant, reduction in the amount of time needed to discharge the chest-pain patients from the emergency department. For those receiving point-of-care troponin testing, those discharged were released in 8.88 hours, whereas those receiving usual-care were discharged in 9.32 hours.

In the per-protocol analysis, there was a borderline significant reduction in the time from first medical discharge to final disposition and a statistically significant reduction in the time needed to discharge the patient from the emergency department.

Overall, there was no effect on clinical outcomes when measured at 30 days, including future visits to the emergency department or rehospitalizations.

Speaking with the media, Ezekowitz said he believes point-of-care troponin testing will evolve over time, leading to increased speed, ease of use, and sensitivity. He suspects the test could one day be used to streamline care for low-risk patients before arriving in the emergency department and to triage hospital therapies in higher-risk chest pain patients.

Dr Kristin Newby (Duke Clinical Research Institute, Durham, NC), the scheduled discussant during the late-breaking clinical-trial session, said the fundamental issue behind the point-of-care testing is to prevent overcrowding and to streamline medical care for patients who present with undifferentiated chest pain, which is the largest single cause of emergency-department admissions in the US.

Like Ezekowitz, Newby noted the study was conducted across five hospitals within a single system with established protocols to manage cardiac emergencies, making it difficult to know how useful point-of-care troponin testing could be in healthcare systems with more fragmented care. Still, the use of point-of-care troponin testing represents "an excellent example of an opportunity for process improvement to streamline care in the emergency department."

PROACT-4 was funded by the Canadian Heart and Stroke Foundation. Ezekowitz had no relevant financial relationships. Disclosures for the coauthors are listed in the abstract.

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