Abstract 723: Optimizing Stress Echocardiography: Diagnostic Capabilities of Velocity Vector Imaging Analysis for Coronary Artery Disease
Diagnostic performance of stress echocardiography (SE) for miocardial ischemia is significantly limited by its subjective evaluation. The new quantitative speckle tracking techniques are a promise of more accurate detection of CAD.
Purpose: Evaluate applicabillity to SE and diagnostic performance for CAD of Velocity Vector Imaging (VVI) derived parameters.
Methods: From 81 positive dobutamine SE, 57 were angiographically validated for both presence and localization of CAD (70.4%) and retrospectively submitted to a VVI blinded analysis, with exclusion of 5 cases due to poor acoustic window. Velocity (V), strain (S), strain rate (SR), displacement (D) and ejection fraction (EF) were analysed at rest and peak stress in 676 normokinetic and 156 hipokinetic segments through T-tests for paired samples, both in longitudinal (l), radial (r), circumferential (c) and rotational (rt) directions. Rest-to-Peak stress (RtoP) gradients [(Xrest-Xpeak)/Xpeak] were evaluated through independent samples T-tests. ROC curves were applied for determination of diagnostic performance for CAD of each parameter.
Results: When compared to normokinetic, hipokinetic segments showed:
Lower rest V (Vl p<0.001, Vr p=0.011, Vrt p=0.003), S (Sl p<0.009), SR (SRl p<0.001), D (Dl p=0.001) and EF (EF p=0.001);
Lower values for all parameters at peak stress (Vl/r/rt, Sl/c, SRl/c, Dl, FE p<0.001, Dr p=0.011);
Lower RtoP gradient for V (Vl p=0.037, Vr p=0.017), S (Sc p=0.035), SR (SRl p=0.018, SRc p<0.001), D (Dl p=0.039) and EF (EF p=0.041).
The best parameters for CAD diagnosis (AUC≥0.75) and respective cut-offs, determined by ROC curve analysis, are displayed in the table⇓ below. None of the parameters showed good diagnostic power at rest.
Conclusions: Applicability of VVI analysis to CAD diagnosis in SE was demonstrated and angiographically validated. The determination of best diagnostic parameters and respective cut-offs is a major step in VVI introduction in clinical practice.