Cardiac testing in A&E examined

The results of the Random Assessment of Treatment using Panel Assay of Cardiac markers (RATPAC) trial,1 suggesting that the use of point-of-care (POC) cardiac marker panels in the accident and emergency (A&E) department can deliver efficiencies by reducing patient stay, have been presented. The preliminary results were communicated at The Association for Clinical Biochemistry Focus meeting, abstracts were presented at the American Association for Clinical Chemistry, and results were published recently in the journal Heart. Each year it is estimated that around 700,000 people are admitted to hospital A&E departments in England and Wales suffering from acute chest pain.2 The current National Institute for Health and Clinical Excellence (NICE) standard is to take troponin measurements on admission and then 12 hours later to rule out acute myocardial infarction. This policy is not consistent across the country, with some hospitals opting for only one troponin measurement. The RATPAC trial, funded by the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) used Siemens Healthcare Diagnostics’ Stratus CS Acute Care analyser sited in emergency departments. The conclusions of the study illustrate that use of the POC cardiac marker panel resulted in a greater proportion of patients being discharged successfully after A&E assessment and a reduction in median (but not mean length of) initial hospital stay. It led to more patients avoiding an in-patient stay over the threemonth follow-up but did not lead to any difference in the total or mean number of in-patient hospital days.

Improving patient care

Current recommendations suggest that patients with suspected myocardial infarction should receive diagnostic testing, with a troponin sample taken 10 to12 hours after symptom onset.3 This approach is inconvenient and potentially costly because it requires many patients to be admitted to hospital unnecessarily until the time delay has elapsed. It has been suggested that the cardiac specificity of troponin measurement be combined with other cytoplasmic markers that may be released earlier. Combined measurement of cardiac troponin, myoglobin and the MB isoenzyme of creatine kinase (CKMB) as a cardiac panel has been proposed as a way to combine early and later markers. Speaking at the Focus meeting, Steve Goodacre, professor of emergency medicine at the University of Sheffield, said: “Acute chest pain is a big problem and it is a quarter of emergency adult admissions. Current standard of care – a 12-hour troponin – usually requires a hospital admission and this can be wasteful and generally not appreciated by patients who don’t want to be in hospital if they don’t have to be. The Department of Health target currently asks for 95% of patients to be through the emergency department in four hours, and NICE asks for a 10 to 12 hour troponin. Therefore, patients often have to be admitted. The POC RATPAC trial looked to challenge existing protocols and asked if it was possible to do better.” Point-of-care testing allows a substantial reduction in turnaround time and rapid provision of results to the A&E department. A panel of cardiac troponin, CK-MB and myoglobin measured by POC testing at baseline and 90 minutes later has been widely evaluated and utilised. Diagnostic cohort studies of this combination report high sensitivity for myocardial infarction, and before-andafter intervention studies suggest its use can reduce turnaround times4 and coronary care unit admissions.5 Despite this anecdotal evidence, no previous prospective randomised, controlled trial of cardiac marker testing in the A&E department had been undertaken. A pragmatic randomised, controlled trial of a POC cardiac marker panel in the management of patients with suspected, but not proven, myocardial infarction in six emergency departments in the UK was performed over an 18-month period, starting in early 2007. Research nurses and A&E department staff screened all patients with chest pain and were randomly allocated to receive either: a) diagnostic assessment using the POC biochemical marker panel, or b) standard care without the panel. Patient groups excluded from the trial are shown in Table 1.