Bedside echocardiography in patients with suspected acute myocardial infarction without ST elevation.

Background: Guidelines recommend using echocardiography in addition to high-sensitivity cardiac troponin (hs-cTn)-based assessment in patients with suspected acute myocardial infarction (MI), although data on its diagnostic and prognostic value is limited.

Methods: Patients presenting with suspected MI without ST elevation to a tertiary center were enrolled. Final diagnoses were adjudicated by two cardiologists. Trained cardiology fellows conducted and interpreted bedside echocardiography in the emergency department as standard of care. Diagnostic performance measures (negative and positive predictive values [NPV, PPV] [95% confidence intervals]) to rule-in or rule-out MI were compared for patients with and without any pathological finding (any wall-motion abnormalities [WMA] or systolic left ventricular dysfunction) in patients assigned to the observe group by a 0/1-hs-cTnI-algorithm. Cox regression analysis was conducted to investigate the association of pathological findings with all-cause death.

Results: Overall, 2779 patients with available echocardiography were included (median age 63 years, 366 [13.2%] with MI, 2158 [77.6%] with data on WMA, median follow-up 5.2 years). The PPV to identify MI using bedside echocardiography in the observe group was low (PPV 8.9 [6.3, 12.5]), and the NPV was 95.6 [93.9, 96.9]. After adjustment for relevant covariates, patients with any compared to no pathological finding  were at increased risk for all-cause death during follow-up (HR 1.36 [1.06, 1.74], p = 0.014).

Conclusions: In this observational study, it could not be shown that bedside echocardiography in the context of suspected acute MI without ST elevation substantially improves diagnostic accuracy beyond hs-cTn-based diagnostic protocols to identify MI in patients assigned to the observe zone. However, findings on echocardiography helped to identify high-risk patients. More prospective evidence on the use of bedside echocardiography is needed to increase the body of evidence. Trial registration ClinicalTrials.gov Identifier: NCT02355457.