Abstract 14848: Can a Quick-Look Exam Improve Echo Referral? Implications for Appropriate and Competent Use of Ultrasound Stethoscopes
Background: As few data exist on how to cost-effectively and competently apply ultrasound stethoscopes, we examined whether a threshold accuracy of any quick-look imaging protocol could potentially improve echo referral.
Methods: We examined 233 consecutive outpt echo studies with lung views for utility of 4 embedded quick-look 2D ultrasound signs for LV systolic dysfunction(LVSD), LA enlargement(LAE), pulmonary edema(Comets) and elevated CVP (IVC+) to identify the standard echo study containing any significant abnormality(AE). Multivariate analysis determined the best-fit combination of signs for diagnostic accuracy. In a strategy in which normal quick look exams negate echo referral, we calculated R, the % reduction of studies per % missed AE for each sign and best-fit combination, using R= [(True Negatives+False negatives)/FN] and modeled R while varying disease prevalence. We compared the R curves to those from algorithms using D-dimer in suspected pulmonary embolism and ETT in suspected coronary disease.
Results: Pt age (mean±SD) was 63±17y, with 45% male. AE was found in 90/233 (39%). Sign [sensitivity, specificity] were: LVSD[14,97], LAE[58,78], Comets[9,93], IVC+[34,94], and best-fit exam (LAE, IVC+) [65,76]. The quick look strategy in this population would reduce echo referral by 60%, but at a 13% risk of missing an AE. According to the model, at a prevalence of 15%, the best-fit exam projected a 70% reduction in referral with the risk of missing an AE of ≤5%. The R curve of the best-fit exam was similar to those of recommended D-dimer[89,32] and ETT[70,70] use (GRAPH).
Conclusions: A quick look 2-view ultrasound exam that lacks signs of elevated venous pressures (LAE, IVC+) can predict the lack of significant echo abnormalities and is best applied on low-risk outpts when the user can attain a sensitivity and specificity of ~70%. Cost, competency and risk boundaries of ultrasound stethoscope use can be modeled as comparable to accepted clinical practice.
- © 2013 by American Heart Association, Inc.