Dynamic left ventricular outflow tract obstruction : clinical and echocardiographic risk factor association in critically ill patients
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Background: Dynamic left ventricular outflow tract obstruction (LVOTO) is increasingly recognized in critically ill patients and is a cause of significant morbidity and mortality. OBJECTIVES: To identify clinical risk predictors that may identify patient at high-risk of developing LVOTO based on their echocardiographic features. METHODS: Clinical and demographic data of all patients diagnosed with acute LVOTO were matched with a randomly derived control group to develop a clinical scoring model (development cohort). Subsequently, a cross sectional study was conducted to validate the scoring model using 143 consecutive patients admitted to intensive care units who underwent echocardiography (validation cohort). A blinded observer classified all patients as either high or low echocardiographic risk for developing LVOTO. Results: The retrospective cross sectional study (of validation cohort) could not validate the clinical score (developed from the development cohort) because it did not differentiate between different LVOTO risk groups (P = 0.54). Univariate analysis suggested female gender (high vs low risk, 64% vs 32%; P = 0.009), age > 60 years (74.8 14.1 vs 57.8 18.4; P = 0.0004) and lack of inotrope use (35% vs 61%; P = 0.03) to be significantly associated with high-risk LVOTO group. All other variables were statistically non-significant. Based on the multiple logistic regression analysis, age > 60 (P = 0.003) was found to be the only independent predictor of high risk for developing LVOTO, with the estimated area under the ROC curve being 0.81. CONCLUSIONS: Elderly patients are at high risk of developing dynamic LVOTO. Other clinical and demographic parameters did not reliably predict risk in our study. Further studies are warranted to improve risk prediction and identification of this, rare but potentially life threatening, cardiac condition before its clinical manifestation.