Abstract 16635: Exercise Magnetic Resonance Imaging to Identify Impaired Pulmonary Vascular and Right Ventricular Reserve in Patients With Normalized Resting Hemodynamics After Pulmonary Endarterectomy
Introduction: Although pulmonary endarterectomy (PEA) is the most efficacious treatment for patients with chronic thromboembolic pulmonary hypertension (CTEPH), patients with normalized pulmonary vascular resistance (PVR) after successful PEA do not always regain a normal exercise capacity.
Methods: 26 healthy controls, 15 CTEPH patients and 7 patients with a normalized mean pulmonary artery pressure (mPAP) post-PEA (25 mmHg) first underwent cardiopulmonary exercise testing to determine peak VO2 and maximal power (Pmax). Then, cardiac MRI with simultaneous invasive mPAP measurement was performed during supine bicycle exercise at 25%, 50% and 66% of Pmax. Biventricular volumes were obtained from endocardial tracings using in-house developed software. Cardiac output (CO) was calculated as stroke volume x heart rate, ejection fraction (EF) as SV / EDV %, tPVR as mPAP / CO and PA compliance (CPA) as stroke volume / PA pulse pressure.
Results: In post-PEA patients, resting tPVR was higher than in controls (P=0.01) but lower than in CTEPH patients (P<0.0001). The slope of mPAP/CO plots was steeper in post-PEA patients than in controls (P<0.0001) and similar to CTEPH (Figure 1A). Relative to controls, resting RVEF was reduced in CTEPH (P<0.0001), but not in post-PEA patients (P=1.0), whilst peak exercise RVEF was reduced both in post-PEA and CTEPH patients (both P<0.0001; Figure 1B). Resting CPA was higher in controls than post-PEA and CTEPH patients (P<0.0001) and correlated strongly with VO2max (R2=0.82, P<0.0001). Despite controls demonstrating the greatest reductions in CPA during exercise, values still remained higher than the resting values in CTEPH and post-PEA patients (p<0.01).
Conclusion: Despite normal resting measures, pulmonary vascular and RV responses to exercise are abnormal in post-PEA patients. Although CPA decreases during exercise in healthy subjects, CPA is significantly lower in CTEPH and post PEA patients at rest and throughout exercise.
Author Disclosures: G. Claessen: None. A. La Gerche: None. S. Dymarkowski: None. P. Claus: None. M. Delcroix: None. H. Heidbuchel: None.
- © 2014 by American Heart Association, Inc.