* Aggregate OA was calculated as the average of the measured OAs for the subjects where all four mid-esophageal planes were available (0° and 90°, as well as 45°and 135°). In the case that only one pair of orthogonal measurements (0° and 90° or 45°and 135°) then the available value was used. 42 of the 61 subjects in the thrombus group and 48 of the 61 subjects in the control group had all four mid-esophageal planes available.
† TEE = transesophageal echo, BMI = body mass index, LVEF = left ventricular ejection fraction, TIA = transient ischemic attack, LA = left atrial, OA = ostial area, LAA = left atrial appendage
Table II summarizes candidate conditional logistical regression models for the outcome presence of LAA thrombus. Model 1 included aggregate OA, LAA exit velocity, and LVEF and was selected as the final model for statistical results and inference based on the lowest AIC (27.578) representing the best goodness-of-fit measurement among the candidate models. Table III summarizes results from the best-fitting conditional regression model (Model 1) examining the relationship of aggregate OA, LAA exit velocity, and LVEF to the primary outcome presence of thrombus. There was a significant association found between aggregate OA and presence of LAA thrombus (p = 0.0038) as well as LAA exit velocity and presence of LAA thrombus (p=0.0107) in the logistic regression model, supporting these two LAA characteristics as risk factors for presence of LAA thrombus. There was no association (p = 0.2161) between LVEF and presence of LAA thrombus in the logistic regression analysis, suggesting that LVEF does not represent an independent risk factor predictive of LAA thrombus. These results are depicted graphically in Figure 3, a Forest plot for the best-fitting conditional logistic regression.
Table II. Candidate Conditional Logistic Regression Models for the Outcome (Thrombus or not)