Echocardiographic Findings Predict In-Hospital and 1-Year Mortality in Left-Sided Native Valve Staphylococcus aureus Endocarditis: Analysis From the International Collaboration on Endocarditis-Prospective Echo Cohort Study

Abstract

Background: Staphylococcus aureus left-sided native valve infective endocarditis (LNVIE) has higher complication and mortality rates compared with endocarditis from other pathogens. Whether echocardiographic variables can predict prognosis in S aureus LNVIE is unknown.

Methods and results: Consecutive patients with LNVIE, enrolled between January 2000 and September 2006, in the International Collaboration on Endocarditis were identified. Subjects without S aureus IE were matched to those with S aureus IE by the propensity of having S aureus. Survival differences were determined using log-rank significance tests. Independent echocardiographic predictors of mortality were identified using Cox-proportional hazards models that included inverse probability of treatment weighting and surgery as a time-dependent covariate. Of 727 subjects with LNVIE and 1-year follow-up, 202 had S aureus IE. One-year survival rates were significantly lower for patients with S aureus IE overall (57% S aureus IE versus 80% non-S aureus IE; P<0.001) and in the propensity-matched cohort (59% S aureus IE versus 68% non-S aureus IE; P<0.05). Intracardiac abscess (hazard ratio, 2.93; 95% confidence interval, 1.52-5.40; P<0.001) and left ventricular ejection fraction <40% (odds ratio, 3.01; 95% confidence interval, 1.35-6.04; P=0.004) were the only independent echocardiographic predictors of in-hospital mortality in S aureus LNVIE. Valve perforation (hazard ratio, 2.16; 95% confidence interval, 1.21-3.68; P=0.006) and intracardiac abscess (hazard ratio, 2.25; 95% confidence interval, 1.26-3.78; P=0.004) were the only independent predictors of 1-year mortality.

Conclusions: S aureus is an independent predictor of 1-year mortality in subjects with LNVIE. In S aureus LNVIE, intracardiac abscess and left ventricular ejection fraction <40% independently predicted in-hospital mortality and intracardiac abscess and valve perforation independently predicted 1-year mortality.

Keywords: echocardiography; endocarditis; odds ratio; risk factors; survival analysis.

Figure 1. Survival analysis for Staphylococcus aureus Left-sided Native Valve Endocarditis

Kaplan Meier survival curves show significantly lower survival rates for Staphylococcus aureus left-sided native valve infective endocarditis in comparison with other pathogens in the overall, non-matched (A) and propensity-matched cohorts (B). Staphylococcus aureus left-sided native valve infective endocarditis was independently associated with 1-year mortality in both non-matched (C) and propensity-matched cohorts (D). ^*Cox proportional hazards modeling of 1-year mortality ^†Stratified Cox proportional hazards modeling of 1-year mortality ^‡Adjusted for age, sex, hemodialysis, heart failure, cerebral embolism, moderate or severe mitral or aortic regurgitation, valvular perforation, cardiac abscess, left ventricular ejection fraction<40%, and cardiac surgery.

Figure 2. Cox Proportional Hazards Model of Clinical and Echocardiographic Variables

Independently Associated with In-hospital and 1-Year Mortality for Staphylococcus aureus Left-sided Native Valve Infective Endocarditis (n=202), with Propensity Adjustment for Cardiac Surgery ^*Native Valve Predisposition includes moderate mitral or aortic regurgitation or stenosis ^†New York Heart Association ^‡Left Ventricular Ejection Fraction