Abstract 18676: Early Changes of Pulmonary Vascular Remodelling After Pulmonary Thrombendarterectomy Measured by Cardiac MRI

Abstract

Purpose: Chronic Thrombembolic Hypertension (CTEPH) occurs in about 3.8% of patients with acute pulmonary embolism. The longterm prognosis is poor, however pulmonary thrombendarterectomy (PEA) offers a potential cure with excellent outcome. Several surrogate markers of pulmonary vascular remodelling have been defined. The max. PA velocity and acceleration time (AT) or its equivalent normalised over ejection times (AT/ET) reflect pulmonary pressure, the relative area change of the PA (RAC) and PA-flow-contour analysis derived dicrotic notch are indicative of changes of pulmonary vascular resistance (PVR). All these parameters can be measured excellently by cardiac magnetic resonance (CMR). In the present study we sought to quantitate surrogate markers of pulmonary vascular remodelling and reverse remodelling before and after PEA by CMR. Methods: patients underwent CMR 2 ± 1 day before and 10 ± 2 days after PEA. Flow/Time curves, PA area and PA max. velocity were derived from Phase-Contrast velocity encoded gradient echo sequences. The temporal resolution was adjusted to 11 ms, sequences were acquired with three signal averages in free breathing to allow for longer acquisition times needed for increased temporal resolution. All numerical data are presented as means ± SD, differences were tested with t-test for paired data, differences in frequencies were tested with McNemar's test. Results: 65 patients were included, mean age 56 ± 16, 28 females. PA peak velocity improved from 61 ± 17 cm/s to 74 ± 19, p = 0.001, AT/ET improved from 0.32 ± 0.06 to 0.36 ± 0.09, p = 0.002, RAC showed a trend to lower values and decreased from 29 ± 1.9% to 25 ± 1.2%, p = 0.1, a diastolic notch was found in 51 of 65 patients before PEA and only in 12 of 65 patients post surgery, p = 0.0001. In those patients in which the notch persisted, there was a trend to smaller notch ratios post PEA 1.37 ± 0.17 vs. 1.12 ± 0.24, p = 0.06. Conclusion: CMR is an excellent tool to monitor pulmonary vascular remodelling after PEA for CTEPH. We were able to demonstrate improved surrogate markers of PA pressure and resistance as early as 10 days after PEA in a large series of 65 patients.