Outcome prediction in sepsis: speckle tracking echocardiography based assessment of myocardial function

Abstract

Introduction: Speckle tracking echocardiography (STE) is a relatively novel and sensitive method for assessing ventricular function and may unmask myocardial dysfunction not appreciated with conventional echocardiography. The association of ventricular dysfunction and prognosis in sepsis is unclear. We sought to evaluate frequency and prognostic value of biventricular function, assessed by STE in patients with severe sepsis or septic shock.

Methods: Over an eighteen-month period, sixty patients were prospectively imaged by transthoracic echocardiography within 24 hours of meeting severe sepsis criteria. Myocardial function assessment included conventional measures and STE. Association with mortality was assessed over 12 months.

Results: Mortality was 33% at 30 days (n = 20) and 48% at 6 months (n = 29). 32% of patients had right ventricle (RV) dysfunction based on conventional assessment compared to 72% assessed with STE. 33% of patients had left ventricle (LV) dysfunction based on ejection fraction compared to 69% assessed with STE. RV free wall longitudinal strain was moderately associated with six-month mortality (OR 1.1, 95% confidence interval, CI, 1.02-1.26, p = 0.02, area under the curve, AUC, 0.68). No other conventional echocardiography or STE method was associated with survival. After adjustment (for example, for mechanical ventilation) severe RV free wall longitudinal strain impairment remained associated with six-month mortality.

Conclusion: STE may unmask systolic dysfunction not seen with conventional echocardiography. RV dysfunction unmasked by STE, especially when severe, was associated with high mortality in patients with severe sepsis or septic shock. LV dysfunction was not associated with survival outcomes.

Figure 1

Longitudinal strain and strain rate curves. (a) Representative recording for apical four-chamber longitudinal strain and strain rate curves for a patient with normal left ventricle (LV) systolic function. Echo image displayed in Mayo format: left, LV; right, right ventricle (RV). Negative strain values indicate tissue contraction. Strain rate determined by change in strain over time. (b) Representative recording for apical four-chamber RV longitudinal strain and strain rate curves for a patient with abnormal RV systolic function. Echo image displayed in Mayo format: left, LV; right, RV. RV free wall longitudinal strain determined by the average of base, mid and apical free wall segments.

Figure 2

Left and right ventricle segmental longitudinal strain values. (A) Graphical representation of left ventricle segmental longitudinal strain with three concentric circles representing apex (inner circle), mid and base (outer circle). (B) Graphical representation of right ventricle segmental free wall longitudinal strain. Data presented as mean ± standard deviation.

Figure 3

Association of right ventricle free wall systolic strain with clinical and echocardiography parameters of disease severity and right ventricular dysfunction. Error bars ± standard deviation. LV, left ventricle; PaO₂/FiO₂, arterial partial pressure of oxygen/fraction of inspired oxygen ratio; RAP, right atrial pressure; RV, right ventricle; SOFA, Sequential Organ Failure Assessment; TV Sm, Tricuspid valve systolic motion velocity.

Figure 4

Kaplan–Meier 1-year survival curves based on right ventricle free wall strain. RV, right ventricle.