FOCUS may detect wall motion abnormalities in patients with ACS

Abstract

Background: Chest pain is a common presentation to the Emergency Department (ED) with roughly 6 million visits a year. The primary diagnostic modality for the identification of acute coronary syndrome (ACS) is the electrocardiogram (ECG), which is used to screen for electrocardiographic findings representing acute coronary occlusion. It is known that the ischemia generated by an acutely occluded coronary vessel generates a wall motion abnormality which can be visualized by echocardiogram; however, emergency physician-performed focused cardiac ultrasound (FOCUS) currently does not have a formal role in the diagnosis of OMI within the emergency department.

Purpose: We sought to define the characteristics of FOCUS performed by emergency physicians of variable training levels in the identification of RWMA in patients presenting to the emergency department with high suspicion for ACS before undergoing cardiac catheterization or formal echocardiography. We also explored whether RWMA was associated with OMI in these patients.

Methods: We performed a structured, retrospective review of adult patients presenting to a large, academic, tertiary care center with suspected ACS from July 1st, 2019, and October 24th, 2020. Patients were included if they underwent FOCUS in the ED during the time-period above for suspected ACS looking for RWMA and FOCUS images were stored and reviewable in our middleware software. The primary outcome was the accuracy, sensitivity, and specificity of FOCUS compared to formal echocardiography for the detection of RWMA. Secondary outcomes were sensitivity of FOCUS compared to formal echocardiography for detection of RWMA in patients with and without cardiac catheterization proven OMI and sensitivity and specificity of FOCUS operators based on training.

Results: FOCUS for RWMA performed by emergency physicians had a sensitivity of 94% (95% CI, 82-98), specificity 35% (95% CI, 15-61), and overall accuracy of 78% (95% CI, 66-87). Of all subjects, 82% underwent urgent or emergency coronary angiography, of which 71% had OMI at the time of coronary angiography of the procedure. FOCUS identified RWMA in 87% of patients with coronary angiography proven OMI. Residents (PGY-1 - PGY-3) (n = 31) were able to detect RWMA with a sensitivity of 86% (95% CI, 64-96), a specificity of 56% (95% CI, 23-85%), and an accuracy of 77 (95% CI, 58-90%). Emergency ultrasound fellows and attendings (n = 34) were able to detect RWMA with a sensitivity of 85% (95% CI, 64-95%), a specificity of 75% (95% CI, 36-96%), and an accuracy of 82% (95% CI, 65-93%).

Conclusions: Our retrospective study concludes FOCUS performed by emergency physicians may be used to detect RWMA in patients with high concern for acute coronary syndrome. This may have its greatest utility in patients presenting without STEMI where the ECG is felt to be equivocal, but the clinician has high concern for OMI, in which the presence of RWMA might result in emergent cath lab activation, though this requires further study. The presence of RWMA in such cases may help to rule in OMI as a cause; however, the absence of RWMA should exclude OMI. Further research is necessary to confirm these findings.

Keywords: Acute coronary syndrome; FOCUS; OMI; POCUS; RWMA.