Use of an accelerated diagnostic protocol (ADP) helped identify patients at a low risk for short-term major adverse cardiac events and increased the number of patients eligible for early discharge, according to the results of the ASPECT trial published online March 22 in the Lancet.

“Every year, an estimated 5 to 10 percent of presentations to emergency departments and up to a quarter of hospital admissions are attributable to symptoms suggestive of acute coronary syndromes,” the authors wrote. “A reliable, reproducible, and more timely process for the identification of chest pain presentations that have a low short-term risk of a major adverse cardiac events is needed to facilitate earlier discharge.”

Martin Than, MD, from the intensive care unit at Christchurch Hospital in Christchurch, New Zealand, and colleagues evaluated 3,582 patients presenting at 14 emergency departments (ED) in nine countries within the Asia-Pacific region with chest pain symptoms to study the safety and efficacy of a two-hour ADP during the ASPECT (Asia-Pacific Evaluation of Chest pain Trial) study.

All patients were over the age of 18, had at least five minutes of chest pain or discomfort and the primary trial endpoint was major adverse cardiac events (MACE) within 30 days of ED presentation. The majority of patients were either white or Chinese and had cardiovascular risk factors.

According to the researchers, the ADP included a of a structured pre-test probability scoring method, including: Thrombolysis in Myocardial Infarction (TIMI) score, ECG, point-of-care biomarker tests of troponin, creatine kinase MB and myoglobin.

Than and colleagues reported that MACE rates occurred in 421 patients within 30 days; STEMI occurred most frequently. The ADP identified 9.8 percent of patients as having a low risk for MACE rates within the 30 days and 0.9 percent of these patients experienced an event. These numbers suggest an ADP sensitivity of 99.3 percent, a negative predictive value of 99.1 percent and the specificity of 11 percent.

In addition, the combination of parameters of the ADP was more effective in identifying patients with MACE compared with individual parameters. However, the researchers reported that combining the biomarkers and ECG without the TIMI score missed 47 patients with adverse events at day 30.

Lastly, Than et al found that patients identified as low risk by a negative ADP were associated with a median initial hospital attendance of 26 hours and a mean of 43.2 hours, or one to two hospital bed-days.

The authors concluded that the two-hour ADP in combination with point-of-care biomarkers, ECG and TIMI scores can identify patients at a low short-term risk of MACE. Because these patients could be discharged earlier to follow-up (three to four hours vs. one to two days), the authors said that this almost 10 percent reduction in patients needing prolonged assessment could potentially reduce hospital overcrowding.

“There is no universally accepted definition of a low-risk patient for acute coronary syndromes,” the authors noted. “The use of a structured and reproducible method is important.”

The authors suggested that the low specificity of ADP (11 percent) could be a limitation; however, they said that the ADP was used as “an exclusion method to predict safety of early discharge of patients and not to establish inpatient management.

“The optimum balance between specificity and sensitivity is difficult to define. A process yielding a higher specificity is likely to discharge a larger number of patients; however, we believe that the main focus should be on safety and therefore sensitivity,” the authors concluded. “Future research should focus on methods to identify a greater proportion of patients who can be discharged earlier without significant adverse events.”

In an accompanying Lancet editorial, Richard Body, MD, of the University of Manchester, Manchester, England, wrote that “predicting just over 80 percent of major adverse cardiac events in an already low-risk population yields an even lower net risk.

“Most people will probably consider this net risk to be statistically acceptable. However, if properly informed, low-risk patients might feel differently about the relative merits of waiting for definitive 6-hour laboratory-based troponin testing or going home after two hours on the basis of results from a test that correctly identifies serious coronary disease, when present, in just over eight of 10 occasions.”

In conclusion, Body wrote that the field must now ask whether the strategy of coupling ADP with the triple-marker tests is optimal, or whether a more sensitive assay would improve performance.