Test Rules Out Heart Attacks in Chest Pain Patients

A blood test administered to patients who present at Accident and Emergency (A&E) departments with chest pain, could significantly reduce the admission rates of patients with heart attack symptoms.

Patients with chest pain make up 10% of A&E attendances and while heart attacks occur in a small segment of these patients and until now, patients have had to wait in hospital for up to 12 hours in order to be certain no evidence of a heart attack could be detected in the blood, with these patients often admitted for monitoring.

Scientists at Bournemouth University (UK) collaborating with international colleagues performed a prospective observational study to evaluate the ability of the Triage Rule-out Using high-Sensitivity Troponin (TRUST) accelerated diagnostic protocol (ADP) to identify low-risk patients with suspected acute coronary syndrome (ACS). Patients with suspected ACS were managed according to the local hospital protocol, which involves risk assessment by emergency department physician staff using the m-Goldman risk score and blood drawn for high-sensitivity troponin (hs-cTnT) at six hours after presentation. As part of the study protocol, blood was also taken at presentation for hs-cTnT analysis.

The fifth generation Roche ELECSYS hs-cTnT assay (Roche, Basel, Switzerland) was used which has a limit of detection (lowest analyte concentration likely to be reliably distinguished from the limit of blank at which detection is feasible) of 5 ng/L, limit of blank (highest apparent analyte concentration expected to be found when replicates of a blank sample containing no analyte are tested) of 3 ng/L, 99th centile of 14 ng/L and 10% coefficient of variation of <10% at 9 ng/L. The primary index test was the TRUST ADP and this defined a patient as “low-risk” if all of the following conditions were satisfied at presentation: a m-Goldman Score of 0 or 1, a non-ischemic electrocardiography (ECG) and a single central laboratory hs-cTnT of less than 14 ng/L at presentation. In all 964 consenting patients were recruited and 99.6% were successfully monitored for 30 days. The TRUST ADP classified 382/960 (39.8%) of patients as at low risk of fatal or non-fatal AMI, with a sensitivity for identifying AMI of 98.8% and a negative predictive value (NPV) of 99.7% and had a similar diagnostic performance for the secondary outcome measure. By using the limit of detection cut-off value of 5 ng/L for the primary outcome measure (AMI) the sensitivity was 100% and 270/922 (29.3%) of patients were eligible for early discharge. The TRUST ADP identified significantly more patients suitable for immediate discharge at 39.8% versus 29.3% (less than 5 ng/L) and 7.9% (less than 3 ng/L) with a lower false-positive rate for acute myocardial infarction (AMI) detection. Edward W. Carlton, PhD, the lead author of the study said, “We were really pleased with the findings of the study as we have shown that our simple but novel diagnostic strategy can potentially reduce the increasing burden on hospitals. It is my hope that this diagnostic tool can be used widely within hospitals in the UK to rule out heart attacks, allay the fears of patients and improve productivity within hospitals.” The study was published on February 17, 2015, in the journal Heart.

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