Abstract 18876: Noninvasive Quantification of Pulmonary Vascular Resistance with Cardiac Magnetic Resonance Imaging
Background: Quantification of pulmonary vascular resistance (PVR) requires invasive right heart catheterization (RHC). Non-invasive Methods of PVR quantification would be valuable in the diagnosis of pulmonary hypertension (PH) and for follow-up.
Hypothesis: A model based on cardiac magnetic resonance (CMR) measurements allows for noninvasive estimation of PVR.
Methods: RHC and CMR were performed on the same day in 100 patients (53 ± 16 years, 73% women) with known or suspected PH. PVR was determined from RHC, and PH was defined as PVR >3 Wood units (n=79, 79%). CMR cine and phase-contrast images were used to measure right ventricular (RV) volumes, RV ejection fraction (RVEF), pulmonary artery (PA) average flow velocity, PA minimal and maximal areas (indexed by body surface area), and cardiac output (calculated as PA net forward volume × heart rate). The study population was randomly divided into a derivation group (n=80) and a validation group (n=20). The best statistical model to predict PVR, based on theoretical principles and statistical criteria (adjusted R2 and Cp Mallows), was obtained from the derivation group. Reliability of the model was assessed in the validation group using Pearson correlation coefficient, Bland-Altman analysis and Kappa coefficient.
Results: Mean PVR was 5.7 ± 4.1 Wood Units (range 0.4–16.4). The CMR-derived model was: PVR = (0.46 × minimal PA area) — (0.08 × RVEF) — (0.24 × PA average velocity) — (0.56 × cardiac output)+12.23. The correlation between invasively quantified and predicted PVR in the validation group was 0.8 (p<0.001; Figure). The mean bias between the RHC-derived and CMR-estimated PVR index was 0.05 Wood units (agreement interval −4.3 to 4.4 Wood units). The model correctly classified 17 (85%) patients with and without PH (Kappa 0.6; p=0.004).
Conclusions: Noninvasive estimation of PVR index using CMR is feasible and may be valuable in PH diagnosis and/or follow-up.
- © 2010 by American Heart Association, Inc.