Prediction of hospital outcome in septic shock: a prospective comparison of tissue Doppler and cardiac biomarkers

Abstract

Introduction: Diastolic dysfunction as demonstrated by tissue Doppler imaging (TDI), particularly E/e' (peak early diastolic transmitral/peak early diastolic mitral annular velocity) is common in critical illness. In septic shock, the prognostic value of TDI is undefined. This study sought to evaluate and compare the prognostic significance of TDI and cardiac biomarkers (B-type natriuretic peptide (BNP); N-terminal proBNP (NTproBNP); troponin T (TnT)) in septic shock. The contribution of fluid management and diastolic dysfunction to elevation of BNP was also evaluated.

Methods: Twenty-one consecutive adult patients from a multidisciplinary intensive care unit underwent transthoracic echocardiography and blood collection within 72 hours of developing septic shock.

Results: Mean +/- SD APACHE III score was 80.1 +/- 23.8. Hospital mortality was 29%. E/e' was significantly higher in hospital non-survivors (15.32 +/- 2.74, survivors 9.05 +/- 2.75; P = 0.0002). Area under ROC curves were E/e' 0.94, TnT 0.86, BNP 0.78 and NTproBNP 0.67. An E/e' threshold of 14.5 offered 100% sensitivity and 83% specificity. Adjustment for APACHE III, cardiac disease, fluid balance and grade of diastolic function, demonstrated E/e' as an independent predictor of hospital mortality (P = 0.019). Multiple linear regression incorporating APACHE III, gender, cardiac disease, fluid balance, noradrenaline dose, C reactive protein, ejection fraction and diastolic dysfunction yielded APACHE III (P = 0.033), fluid balance (P = 0.001) and diastolic dysfunction (P = 0.009) as independent predictors of BNP concentration.

Conclusions: E/e' is an independent predictor of hospital survival in septic shock. It offers better discrimination between survivors and non-survivors than cardiac biomarkers. Fluid balance and diastolic dysfunction were independent predictors of BNP concentration in septic shock.

Figure 1

Receiver operating characteristic curve comparing E/e' with BNP, and TnT as discriminators of hospital mortality. BNP, B-type natriuretic peptide; E/e', ratio of peak early diastolic transmitral flow velocity to peak early diastolic septal mitral annulus; TnT, Troponin T.

Figure 2

Kaplan Meier plot of association between E/e' and hospital survival. Cases are censored at hospital discharge. E/e', ratio of peak early diastolic transmitral flow velocity to peak early diastolic septal mitral annulus.