Low myocardial work assessed by echocardiography is associated with prolonged ICU-Stay in CABG patients

The aim of this study was to investigate whether echocardiographic assessment of myocardial work is a predictor of outcome in patients undergoing operative revascularization.

Global work index (GWI) is calculated by means of speckle tracking, blood pressure measurement at the moment of strain analysis, and a normalized reference curve. The prognostic value of GWI in patients who are scheduled for bypass surgery is unknown.

In this retrospective analysis, 193 patients scheduled for a bypass operation were tracked using echocardiographic strain measurement and calculation of the Global Longitudinal Strain (GLS), the GWI and ejection fraction concerning outcome parameters. The primary endpoint was the occurrence of intrahospital major cardiac events (MACE). As secondary endpoints, prolonged ICU stay (more than 24 hours), requirement for catecholamines (more than 12 hours) and duration of mechanical ventilation (mora than 12 hours) were defined as well as all-cause mortality within a year. Both GWI, EF, and Strain were examined for their validity with respect to the primary and secondary endpoints.

The mean patient age was 63.41 years (SD 8.67). The median left ventricular ejection fraction was 53.78 % [IQR 48.30, 57.46] and the median global longitudinal strain -14.73 % [IQR-17.20, -11.87]. The median GWI was 1428.00mmHg% [IQR 1074.00, 1725.00]. Regarding the primary endpoint, no statistically significant differences were found between patients with a GWI of over 1000 mmHg% and those with a GWI of under 1000 mmHg% (p=0.281), which can be attributed to the low number of MACE events (n=13). For the secondary endpoints, there was no significant difference in terms of the duration of mechanical ventilation between patients with a GWI of under or over 1000 mmHg% (p= 0.879). However, there was a significantly higher risk for a longer stay in the ICU (OR 3.44, 95%CI [1.54, 8.33], p=0.004) among patients with a GWI of under 1000 mmHg%, and furthermore, a higher requirement for catecholamines was observed (p= 0.007).

GWI is associated with prolonged ICU Stay above 24 hours and requirement for catecholamines, but not for mace or ventilation time.