Diagnostic accuracy of inferior vena cava ultrasound for heart failure in patients with acute dyspnoea: A systematic review and meta-analysis

Background: Dyspnoea is the most common sign of heart failure (HF). Patients accessing the ED for HF-related symptoms require fast diagnosis and early treatment. Transthoracic echocardiography has a crucial role in HF diagnosis, but requires qualified staff and adequate time for execution. The measurement of inferior vena cava (IVC) diameter has been recently proposed as a rapid, simple and reliable marker of volume overload. The aim of this systematic review was to assess the accuracy of IVC-ultrasound as a stand-alone test for HF diagnosis in patients presenting to the ED with acute dyspnoea. Methods: Studies evaluating the diagnostic accuracy of the inferior vena cava collapsibility index (IVC-CIx) for HF diagnosis were systematically searched in the EMBASE and MEDLINE databases (up to January 2018). Quality Assessment of Diagnostic Accuracy Studies 2 tool was used for the quality assessment of the primary studies. A bivariate random-effects regression approach was used for summary estimates of both sensitivity and specificity. Results: Seven studies, for a total of 591 patients, were included. Three studies were at low-risk of bias. All studies used a proper reference test. Weighted mean prevalence of HF was 49.3% at random-effect model (I2 index for heterogeneity=74.7%). IVC-CIx bivariate weighted mean sensitivity was 79.1% (95% CI 68.5% to 86.8%) and bivariate weighted mean specificity was 81.8% (95% CI 75.0% to 87.0%). Conclusions: Our findings suggest that the sensitivity and specificity of IVC-CIx are suboptimal to rule in or rule out HF diagnosis in patients with acute dyspnoea in the ED setting. Therefore, IVC-CIx is not advisable as a stand-alone test, but may be useful when integrated in a specific diagnostic algorithm for the differential diagnosis of acute dyspnoea.