Predictive accuracy of velocity time integral in predicting in-hospital outcomes in patients with intermediate-risk pulmonary embolism: a systematic review and meta-analysis.

Intermediate-risk pulmonary embolism (IRPE) is a critical clinical entity with significant mortality risk due to normotensive shock, a condition marked by low cardiac index despite maintained blood pressure. Accurate and timely detection of hemodynamic compromise in IRPE remains a challenge. Velocity Time Integral (VTI), a Doppler echocardiographic parameter, has emerged as a potential non-invasive tool for predicting hospital outcomes, but the evidence remains fragmented. This systematic review and meta-analysis aim to evaluate the diagnostic accuracy of VTI in this context. A systematic literature search encompassing PubMed, EMBASE, and SCOPUS Databases was conducted from inception till December 2024. Studies assessing VTI's diagnostic accuracy for predicting hospital outcomes in IRPE were included. A bivariate random-effects model was used to pool sensitivity and specificity, with heterogeneity analyzed via I² statistics and meta-regression. Literature search yielded 9 studies with 2038 patients. Pooled sensitivity and specificity of VTI for predicting hospital outcomes in IRPE were 79% (95% CI 69-86%) and 81% (95% CI 70-88%), respectively. Diagnostic odds ratio was 15.58 (95% CI: 7.42-32.69). Heterogeneity was moderate to high (I² = 66.59%), with specificity showing greater variability. Meta-regression identified study-level characteristics, including risk of bias and VTI measurement site (LVOT vs. RVOT), as sources of variability. VTI demonstrates moderate sensitivity and specificity in predicting hospital outcomes such as mortality, in-hospital mortality, resuscitated cardiac arrest, hemodynamic instability or the need for reperfusion therapy.  VTI, offers a non-invasive, real-time diagnostic option. However, study heterogeneity and methodological limitations highlight the need for further research.