Prehospital risk stratification in non-ST-elevation acute coronary syndrome; a paramedic echocardiography pilot study.

Abstract

Background Prehospital risk stratification and timing of revascularization in Acute Coronary Syndromes (ACS) is currently based on the electrocardiogram (ECG). ST- elevation in the ECG indicates myocardial infarction (STEMI) in need of immediate reperfusion therapy. However, a large group of ACS patients presents without ST-elevation in ECG, despite coronary occlusions. In these high risk non-ST-elevation myocardial infarctions (NSTEMI), immediate reperfusion may be just as crucial for the prognosis, but prehospital diagnostic tools to identify them are lacking. Objective This pilot study investigated if focused prehospital transthoracic echocardiography (TTE) images achieved by paramedics could be transferred to the in-hospital cardiologist for diagnostic evaluation, and test if this, in combination with a point-of-care (POC) high-sensitive Troponin-T (Hs-cTnT) test, facilitates prehospital identification of high risk NSTE-ACS. Methods Paramedics were trained to obtain focused prehospital TTE images and provide POC Hs-cTnT - testing in patients with suspected ACS. The information was transferred to the in-hospital cardiologist who determined the treatment strategy by evaluating the information provided by the paramedics. Results 123 patients were included between November 30 th 2017 and November 30 th 2018. TTE images were interpretable in 107 cases (87%), and Hs-cTnT measures in 113 cases (93%). NSTEMI was the final diagnosis in 16 patients (13%), where 13 got admitted directly for percutaneous coronary intervention (PCI). These patients bypassed the local hospital and saved time to treatment based on the prehospital detection of NSTE-ACS. Conclusion Interpretable focused TTE images and POC Hs-cTnT measures can be achieved by paramedics in most patients with suspected NSTE-ACS. This information seems to aid in-hospital cardiologist admitting the right patients to the PCI hospital. The study strongly indicates that prehospital diagnostics and risk assessment of patients with suspected NSTE-ACS is feasible. A larger study is needed to clarify the diagnostic accuracy of focused prehospital TTE in suspected NSTE-ACSTrial registration Clinical trials NCT04223986, ID: 17/05178-2 – 522). Registered retrospectively September 23rd 2018. https://clinicaltrials.gov/show/NCT04223986.