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Echocardiographic left ventricular stroke work index: An integrated noninvasive measure of shock severity
Jacob C Jentzer1,2, Brandon M Wiley1, Nandan S Anavekar1
1Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, United States of America.
Insights
Left ventricular stroke work index (LVSWI) measured by echocardiography can predict mortality in cardiac intensive care unit (CICU) patients. Lower LVSWI values identify high-risk patients across all Society for Cardiovascular Angiography and Intervention (SCAI) shock stages.
Area of Science:
- Cardiology
- Critical Care Medicine
- Echocardiography
Background:
- Echocardiographic findings correlate with shock severity, categorized by Society for Cardiovascular Angiography and Intervention (SCAI) shock stages.
- Left ventricular stroke work index (LVSWI) assessed via transthoracic echocardiography (TTE) is a mortality predictor in the cardiac intensive care unit (CICU).
Purpose of the Study:
- To evaluate if LVSWI can enhance mortality risk stratification within the SCAI shock classification system in the CICU.
- To determine the prognostic value of LVSWI in predicting in-hospital mortality across different SCAI shock stages.
Main Methods:
- A cohort of 3635 CICU patients from 2007-2015 with available TTE data was analyzed.
- LVSWI was calculated using mean arterial pressure, stroke volume index, and medial mitral E/e' ratio.
- Logistic regression models assessed in-hospital mortality as a function of LVSWI across SCAI shock stages, with and without multivariable adjustment.
Main Results:
- LVSWI progressively decreased with increasing SCAI shock stage.
- In-hospital mortality was higher in patients with lower LVSWI (adjusted OR 0.66 per 10 J/m2 higher) and higher SCAI shock stage (adjusted OR 1.24 per stage).
- A LVSWI <33 J/m2 was significantly associated with increased adjusted in-hospital mortality, especially in patients with SCAI shock stages C, D, and E.
Conclusions:
- Transthoracic echocardiography-derived LVSWI noninvasively quantifies shock severity, incorporating both systolic and diastolic dysfunction.
- LVSWI effectively identifies low- and high-risk patients across all clinical shock severity levels.
- LVSWI serves as a valuable tool for refining mortality risk assessment in critically ill cardiac patients presenting with shock.
Background:
Echocardiographic findings vary with shock severity, as defined by the Society for Cardiovascular Angiography and Intervention (SCAI) shock stage. Left ventricular stroke work index (LVSWI) measured by transthoracic echocardiography (TTE) can predict mortality in the cardiac intensive care unit (CICU). We sought to determine whether LVSWI could refine mortality risk stratification by the SCAI shock classification in the CICU.
Methods:
We included consecutive CICU patients from 2007 to 2015 with TTE data available to calculate the LVSWI, specifically the mean arterial pressure, stroke volume index and medial mitral E/e' ratio. In-hospital mortality as a function of LVSWI was evaluated across the SCAI shock stages using logistic regression, before and after multivariable adjustment.
Results:
We included 3635 unique CICU patients, with a mean age of 68.1 ± 14.5 years (36.5% females); 61.1% of patients had an acute coronary syndrome. The LVSWI progressively decreased with increasing shock severity, as defined by increasing SCAI shock stage. A total of 203 (5.6%) patients died during hospitalization, with higher in-hospital mortality among patients with lower LVSWI (adjusted OR 0.66 per 10 J/m2 higher) or higher SCAI shock stage (adjusted OR 1.24 per each higher stage). A LVSWI <33 J/m2 was associated with higher adjusted in-hospital mortality, particularly among patients with shock (SCAI stages C, D and E).
Conclusions:
The LVSWI by TTE noninvasively characterizes the severity of shock, including both systolic and diastolic parameters, and can identify low-risk and high-risk patients at each level of clinical shock severity.
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