Abstract
Abstract Background The widespread adoption of high-sensitivity cardiac troponin testing has encouraged the use of pathways to accelerate the rule-out and rule-in myocardial infarction in the Emergency Department. These pathways are not recommended for patients with ST-segment elevation, but there is a risk they may be applied incorrectly given that interpretation of the electrocardiogram is subjective, dependent on experience, and signs may be masked in those with posterior myocardial infarction. Methods Consecutive patients with suspected acute coronary syndrome were enrolled in a stepped-wedge cluster randomized controlled trial across ten hospitals in Scotland. The index diagnosis was adjudicated two clinicians independently in all patients with high-sensitivity cardiac troponin I concentrations above the sex-specific 99th centile on serial testing and abnormalities on the electrocardiogram recorded. The proportion of patients with ST-segment elevation myocardial infarction and concentrations below the rule-out threshold (<5 ng/L), 99th centile (<16 ng/L and <34 ng/L for women and men) and rule-in threshold (<52 ng/L) at presentation were determined. Results In total 48,282 patients were recruited between June 2013, and March 2016 of which 22% (10,360/48,282) had peak cardiac troponin concentrations above the 99th centile. The adjudicated diagnosis was type 1 myocardial infarction in 55% (4,981/9,115) of patients and 10% (925/9,115) had ST-segment elevation myocardial infarction (age 65 [14] years, 68% men). The majority presented within 6 hours of symptom onset (67%, 619/925), and 84% (772/925) had cardiac troponin concentrations above the 99th centile at presentation. However, troponin concentrations were below the rule-out threshold in 2% (20/925) and the rule-in threshold in 26% (240/925) of patients with ST-segment elevation myocardial infarction. Discussion In patients with suspected acute coronary syndrome who have a final diagnosis of ST-segment elevation myocardial infarction, high-sensitivity cardiac troponin concentrations are below the rule-out and rule-in threshold at presentation in 1 in 50 and 1 in 4 patients, respectively. Clinicians should not rely on cardiac troponin concentrations to guide initial treatment decisions in patients with possible ST-segment elevation myocardial infarction. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): British Heart Foundation
Highlights
The introduction of high-sensitivity cardiac troponin testing into clinical practice has transformed the assessment of patients with suspected acute coronary syndrome in the Emergency Department.[1]
Patients presenting within 2 hours were more likely to have a troponin concentration below the 99th-centile, even in those who presented later, 1 in 6 had troponin concentrations below the diagnostic threshold
Abrupt coronary occlusion may prevent the release of troponin into the circulation until reperfusion has occurred
Summary
The introduction of high-sensitivity cardiac troponin testing into clinical practice has transformed the assessment of patients with suspected acute coronary syndrome in the Emergency Department.[1] The majority of patients can be discharged using accelerated diagnostic pathways that do not require hospital admission for peak cardiac troponin testing.[2] These pathways are not recommended for patients with ST-segment elevation on the electrocardiogram,[3,4] but given interpretation is dependent on experience, there is a risk patients could be inappropriately assessed
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