Abstract 9296: Prediction of Six Minute Walk Test Distance Using ECG Gated 320 Slice CT, Echocardiogram and Right Heart Catheter Examinations in Subjects with Pulmonary Hypertension in Multiple Regression Models
Purpose: The six minute walk test (6MWT) as defined by the American Thoracic Society integrates responses of pulmonary and cardiovascular systems. We tried to predict 6MWT distance in subjects with pulmonary hypertension (PH) using 320 slice CT, transthoracic echocardiogram (TTE), and right heart catheter (RHC) examinations.
Materials and Methods: 16 consecutive PH subjects (11 female, mean 54 years, 7 primary PH, 9 chronic pulmonary arterial thromboembolism) underwent retrospective ECG gated 320 slice CT, RHC and 6MWT. CT images were reconstructed every 5% from 0-95% of R-R interval. We quantified right ventricular (RV) end systole volumes (RVESV) and end diastole volumes (RVEDV), and RV ejection fraction (RVEF) by CT, maximum RV area (maxRVA) and RV fractional area change (RVFAC) by TTE, and mean pulmonary artery pressure (MPAP) by RHC.
Results: RVEDV and RVEF were 143.8±53.2ml and 46.7±10.6%. maxRVA, RVFAC on TTE, MPAP on RHC and 6MWT distance were 26.7±5.8, 29.1±8.9%, 35.8±14.2mmHg, and 404.8±85.7m. A significant positive correlation was seen between 6MWT distance and RVFAC (0.626, P=0.01), and a negative correlation was seen between 6MWT distance and, RVEDV and MPAP (r=-0.635, and -0.648, p<0.01). All predictor variables using CT and RHC were analyzed and 6MWT distance was predicted by multiple regression formula: Y=-3.0X1 -0.6X2 -2.2X3 -45.3X4 -0.7X5 +814.1 (Y=6MWT distance, X1=age (yrs), X2= RVEDV, X3=MPAP, X4=female gender, X5= RVEF) (R2=0.725, p<0.05). All predictor variables using TTE and RHC were analyzed and 6MWT distance was predicted by multiple regression formula Y=4.2X1 -2.7X2 -57.8X3 -1.5X4 +2.4X5 +461.6 (Y= 6MWT distance, X1=RVFAC, X2=age, X3=female gender, X4 MPAP, X5=maxRVA) (R2=0.719, p<0.05).
Conclusion: 6MWT distance can be predicted by 320 slice CT as well as or slightly better than by TTE and RHC. RVEDV on CT and MPAP on RHC may be negative predictors and RVFAC on TTE may be a positive predictor for estimating 6MWT distance in subjects with PH.
- © 2011 by American Heart Association, Inc.