Baseline Echocardiographic Predictors of Dynamic Intraventricular Obstruction of the Left Ventricle during Dobutamine Stress Echocardiogram

Abstract

Intraventricular obstruction (IVO) during dobutamine stress echocardiogram (DSE) may be associated with or reproduce symptoms. Predictors of IVO are not well established. 149 patients were studied at rest and during DSE. The normal range of the left ventricular outflow tract (LVOT) velocities was investigated in 68 healthy patients. 19 patients (13%) developed IVO (peak LVOT velocity > 271 cm/sec). A significant linear correlation was observed between peak LVOT velocity during DSE and the following rest parameters: LV end-diastolic dimension (r =-0.20, P = 0.018), LV end-systolic dimension (r =- 0.27, P = 0.001), relative wall thickness (r = 0.23, P = 0.006), shortening fraction (r = 0.24, P = 0.004), LVOT diameter (r =- 0.20, P = 0.023) and LVOT velocity (r = 0.29, P < 0.0001). Only relative wall thickness (P = 0.012) and LVOT diameter (P = 0.027) were independent predictors of IVO. As a dichotomous variable, a relative wall thickness > or =0.44 was the only independent predictor of IVO (OR 5.7, 95% CI 1.6-20, P = 0.006), with sensitivity, specificity, negative predictive value, and positive predictive value of 77%, 62%, 95%, and 21%, respectively, and global accuracy of 63% (area under the ROC curve = 0.7). IVO was significantly associated with general cardiovascular symptoms (P = 0.0006) and with chest pain (P = 0.008). Relative wall thickness and LVOT diameter were independent predictors of obstruction. As a dichotomous variable, a relative wall thickness < or = 0.44 was the only independent predictor of dynamic IVO.