Conference: 2012 International PHA Conference and Scientific Sessions
Release Date: 06.22.2012
Presentation Type: Abstracts
Stream, A MD, Rice, J BA, Geraci, M MD, Dorosz, J MD, Bull, T MD
University of Colorado Health Sciences Center, United States
OBJECTIVE: Pulmonary hypertension (PH) is a common complication of chronic obstructive pulmonary disease (COPD). PH is associated with increased health care utilization and increased mortality in this patient population. Current echocardiographic measures used to estimate pulmonary arterial pressure (PAP) are inadequate with poor predictive value for the diagnosis of PH in subjects with COPD. 2-Dimensional (2D) myocardial strain obtained by speckle tracking echocardiography (STE) is a measure of myocardial deformation which has been validated for the assessment of left ventricular function. Unlike other echocardiographic methods used to estimate right ventricular (RV) function and PAP, 2D strain measurements are independent of acquisition angle and preload status. Additionally, RV longitudinal strain has recently been shown to correlate well RV function and PAP as well as survival in subjects with pulmonary arterial hypertension (PAH). We hypothesized that RV strain measurements would be more readily obtained than estimates of PAP from tricuspid regurgitation (TR) velocity in subjects with severe COPD and that reduced absolute values of RV strain would correlate with invasive hemodynamic measurements indicative of PH such as pulmonary vascular resistance (PVR).
METHODS: We retrospectively obtained RV free wall average longitudinal strain values using 2-dimensional STE on standard, four chamber apical views from subjects with severe (Global initiative for Obstructive Lung Disease, GOLD stage IV) but stable COPD who had undergone echocardiography within 48 hours of pulmonary artery catheterization (PAC).
RESULTS: We identified 54 subjects with complete data for inclusion in the analysis. TR was identified in only 17 (31%) while RV strain could be obtained from at least one apical view in 44 (81%). The absolute value of RV free wall average longitudinal strain was inversely correlated with PVR (r2 0.17, p 0.02). Using PVR to define pulmonary vascular dysfunction, subjects with a PVR>3 were compared to those with PVR</= 3 using the Wilcoxon rank sum test for nonparametric data. The median RV free wall strain among subjects with PVR </= 3 was -23% (interquartile range -29% to -15%) versus -20% for those with PVR>3 (interquartile range -23% to -12%), p 0.05. Using the same PVR cut-off of 3, the receiver operating characteristic curve demonstrated that an RV free wall strain of -24% was 92% sensitive and 42% specific at identifying pulmonary vascular dysfunction (AUC 0.74).
CONCLUSION: RV strain can be obtained from standard echocardiographic views in the majority of subjects with severe COPD while estimates of PAP using TR are rarely obtainable. Absolute values of RV free wall strain are reduced with pulmonary vascular dysfunction varying inversely with PVR and may be a means of improving screening for PH in subjects with COPD, assisting in the selection of those who merit further invasive studies such as PAC.