Evaluation of Ambulance Based Troponin Measurements : A Feasibility and Impact Pilot Study of the Utility of pre-Hospital POC Testing of Cardiac Biomarkers on Patients Presenting with Acute Chest Pain

Bluestein, Barry and Scotland, Susan and Nicoll, Gordon and Barclay, K. and Kim, Dongwoo and Lunts, Phillip and Baxter, Colin and Miller, George (2013) Evaluation of Ambulance Based Troponin Measurements : A Feasibility and Impact Pilot Study of the Utility of pre-Hospital POC Testing of Cardiac Biomarkers on Patients Presenting with Acute Chest Pain. [Report]

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    Abstract

    This final report is a Summary of a Phase 1 Program to determine the feasibility and logistics of performing Cardiac Biomarker measurements in the ambulance setting with paramedics. Specifically the report presents the findings and a list of recommendations relative to the measurement of cardiac TnI (cTnI) from patients presenting with chest pain prior to and during transit to a primary care hospital (Borders General Hospital-BGH) via the Scottish Ambulance Service. (SAS). The immunoassay system used to quantitatively determine cTnI was the Samsung LABGEOIB10 (BCA-IB10). While patients presenting with chest pain suggestive of myocardial infarction (MI) can be diagnosed by paramedics almost immediately via 12 lead ECG telemetry, that subset of patients with no significant and persistent ST segment elevation (NSTEMI) or normal ECG are not eligible for administration of thrombolytic agents and are routinely dispatched according to the current chest pain pathway to the Borders General Hospital in Melrose. STEMI patients are immediately rerouted to a secondary or tertiary hospital with interventional cardiology capability to perform angiography, PCI or more complicated procedures to identify and resolve cardiac ischemia (Royal Infirmary of Edinburgh). Patients with NSTEMI or acute coronary syndrome (ACS) require, as part of their differential diagnosis, at least 1 elevated concentration of cTnI which may include serial measurements if the initial concentration is near or just below the designated cut –off, usually defined as the 99th percentile concentration of an apparently healthy reference population. Every cTnI assay establishes it’s own cut point and they may vary significantly. Elevated cTnI levels correlate with the risk of mortality, MI or increased probability of ischemic events, requiring urgent revascularization. The recently published Third Universal Definition of Myocardial Infarction approved by an International Task Force endorsed by the European Society of Cardiology (ESC), American College of Cardiology Federation (ACCF), World Heart Federation (WHF) and the American Heart Association (AHA) requires at least one elevation of cTnI above the 99 percentile of a reference population (Table 1) with 2-3 samples taken over a period up to 12 h. Several previous studies using quantitative point of care devices (POC) in the Emergency Department have demonstrated total turn around times (TAT) of 30 minutes or less compared to cTnI report times from the central lab of > 1 h.2 One such study found a TAT reduction of 50-60% in both urban and community based hospitals for reporting ED cardiac marker test results compared to cTnI results reported submitted to the laboratory. A more recent report from a randomized study comprising 6 ED departments in the UK ,with approximately 1130 patients in each arm (ED cardiac marker testing compared to standard laboratory based reporting), was undertaken to assess the possibility of earlier dismissal from the hospital compared to the current National Institute for Health and Clinical Excellence guidelines of 10-12 h3 The RATPAC (Randomized Assessment of Treatment using a Panel Assay of Cardiac Markers) protocol was based on POC testing at presentation and a second test 90 minutes later. Main outcome measures for RATPAC were: * Successful discharge by 4 hr after attendance -32% vs 13% (rapid rule out); * Reduced median length of initial hospital stay; * Greater use of coronary care unit