The diagnostic accuracy of cardiac ultrasound for acute myocardial ischemia in the emergency department: a systematic review and meta-analysis

Abstract

Background: Chest pain is responsible for millions of visits to the emergency department (ED) annually. Cardiac ultrasound can detect ischemic changes, but varying accuracy estimates have been reported in previous studies. We synthetized the available evidence to yield more precise estimates of the accuracy of cardiac ultrasound for acute myocardial ischemia in patients with chest pain in the ED and to assess the effect of different clinical characteristics on test accuracy.

Methods: A systematic search for studies assessing the diagnostic accuracy of cardiac ultrasound for myocardial ischemia in the ED was conducted in MEDLINE, EMBASE, CENTRAL, CINAHL, LILACS, Web of Science, two trial registries and supplementary methods, from inception to December 6th, 2022. Prospective cohort, cross-sectional, case-control studies and randomized controlled trials (RCTs) that included data on diagnostic accuracy were included. Risk of bias was assessed with the QUADAS-2 tool and a bivariate hierarchical model was used for meta-analysis with paired Forest and SROC plots used to present the results. Subgroup analyses was conducted on clinically relevant factors.

Results: Twenty-nine studies were included, with 5043 patients. The overall summary sensitivity was 79.3% (95%CI 69.0-86.8%) and specificity was 87.3% (95%CI 79.9-92.2%), with substantial heterogeneity. Subgroup analyses showed increased sensitivity in studies where ultrasound was conducted at ED admission and increased specificity in studies that excluded patients with previous heart disease, when the target condition was acute coronary syndrome, or when final chart review was used as the reference standard. There was very low certainty in the results based on serious risk of bias and indirectness in most studies.

Conclusions: Cardiac ultrasound may have a potential role in the diagnostic pathway of myocardial ischemia in the ED; however, a pooled accuracy must be interpreted cautiously given substantial heterogeneity and that important patient and test characteristics affect its diagnostic performance.

Protocol registration: PROSPERO (CRD42023392058).

Keywords: Echocardiography; Emergency department; Ischemia; Myocardial infarction; POCUS; Point-of-care; Ultrasound.

Fig. 1

PRISMA flow diagram of search results and study selection

Fig. 2

Risk of bias and applicability concerns graph (A) and summary table (B): Review author’s judgements about each domain are presented as percentages across included studies and for each included study

Fig. 3

Paired Forest plot of sensitivity and specificity of all included studies. TP = true positive, TN = true negative, FP = false positive, FN = false negative

Fig. 4

SROC plot of sensitivity and specificity of all included studies. Each study is represented by a circle, with the size of the circle indicating the size of the sample

Fig. 5

SROC plot of sensitivity and specificity in subgroup analyses, according to A = Patient Spectrum, B = Ultrasound Operator, C = Timing of Ultrasound, D = Ultrasound Device, E = Type of Ultrasound Protocol, F = Reference Standard, G = Target Condition. Diamond: summary estimate, dashed line: 95% confidence region, dotted line: 95% prediction region