Fig 1.
Calculation of the ECHO-LVSWI (left) and an example using TTE data from a patient with cardiogenic shock (right). The stroke volume index (SVI) is calculated using the left ventricular outflow tract (LVOT) velocity-time integral (VTI) by spectral Doppler, indexed to the body surface area. The LVEDP is estimated using the ratio of the peak mitral early diastolic (E) wave velocity by spectral Doppler to the peak mitral early diastolic (e’) wave velocity by tissue Doppler via the formula LVEDP = 4.9 + 0.62 * mitral E/e’ ratio [17,23]. We used the medial/septal mitral e’ velocity for this analysis, although our data suggest that either the lateral or mean e’ velocity could be substituted. The mean arterial pressure (MAP) was determined either invasively or noninvasively and estimated as (systolic blood pressure + 2 * diastolic blood pressure) / 3. We used the formula ECHO-LVSWI = 0.0136 * SVI * (MAP–LVEDP) [17,23].
Fig 2.
Flow diagram showing study inclusion and exclusion criteria.
CICU, cardiac intensive care unit; LVSWI, left ventricular stroke work index; SCAI, Society for cardiovascular Angiography and Intervention; TTE, transthoracic echocardiogram.
Fig 3.
Mean ECHO-LVSWI (left) and distribution of ECHO-LVSWI (right) as a function of SCAI shock stage.
Table 1.
Baseline characteristics, comorbidities, admission diagnoses and therapies of patients according to SCAI shock stages.
Data reported as mean ± standard deviation for continuous variables and number (percent) for categorical variables. P value is for linear regression (continuous variables) or logistic regression (categorical variables) across SCAI shock stages.
Table 2.
Echocardiographic findings of patients according to SCAI shock stages.
Data reported as mean ± standard deviation for continuous variables and number (percent) for categorical variables. P value is for linear regression (continuous variables) or logistic regression (categorical variables) across SCAI shock stages.
Table 3.
Unadjusted odds ratio (OR) and 95% confidence interval values for quartiles of selected echocardiographic for prediction of in-hospital mortality using univariable logistic regression, with Quartile 4 as referent.
Median and interquartile range values defining the quartiles are as follows: ECHO LVSWI, 37.0 (21.0, 46.1) J/m2; CI, 2.8 (2.4, 3.3) L/min/m2; LVEF, 51 (36, 61) %; SVI, 41 (33, 47) ml/m2.
Table 4.
Optimal cut-off (maximum value of Youden’s J index = sensitivity + specificity– 1) with the associated sensitivity, specificity and overall accuracy for selected echocardiographic variables for prediction of in-hospital mortality using univariable logistic regression.
Fig 4.
In-hospital mortality as a function of SCAI shock stage stratified by ECHO-LVSWI group (left) and for patients with ECHO-LVSWI < or ≥33.1 J/m2 (right).
Fig 5.
Forest plots showing unadjusted (left) and adjusted (right) odds ratio (OR) values for ECHO-LVSWI (per each 10 J/m2 higher) overall and in each SCAI shock stage.
Fig 6.
Classification and regression tree (CART) analysis using ECHO-LVSWI and SCAI shock stage for stratification of in-hospital mortality risk.
Table 5.
Predictors of in-hospital mortality using multivariable logistic regression with stepwise backward variable selection to minimize the AIC value.