Synthesis of CT Imaging and Right Heart Catheterization Enables Single-Beat RV-PA Coupling Estimations in Heart Failure Patients

Abstract

<h3>Purpose</h3> Right ventricular-pulmonary arterial (RV-PA) coupling has been shown to predict RV failure in PH patients. However, current clinical approaches require physiological assumptions which may be invalid in heart failure patients. We utilized functional CT and right heart catheterization (RHC) to construct single-beat pressure-volume (PV) loops, assess the impact of coupling assumptions, and compare impact on predicting patient outcomes. <h3>Methods</h3> Heart failure patients who underwent advanced therapy evaluation between since 9/2017 with ECG-gated contrast-enhanced CT scans and RHC within 14 days were enrolled. PV loops were generated via synchronizing CT-derived volume and RHC-derived pressure waveforms. A model using PV data and RV wall thickness was used to fit RV and PA elastance. We compared our approach to two clinical alternatives: volumetric approach, which estimates coupling as stroke volume / end-systolic volume (SV/ESV), and pressure adjusted approach, estimated as (SV * ESP) / (ESV * mPAP). The prognostic value of the coupling approaches was evaluated using a composite endpoint of heart transplant due to ventricular decompensation, VAD implantation with RV failure, or cardiac related death within 30 days. <h3>Results</h3> 22 patients met inclusion criteria and within 30 days, 7 had the composite endpoint (3 deaths, 2 RV failure post VAD, 2 transplants), and 15 did not (2 VAD with no RV failure, 13 no events). Compared to the single-beat PV-loop based approach, both the volumetric approach (75.2% reduction) and pressure-adjusted approach (45.6% reduction) underestimated coupling. PV-derived coupling was significantly (p<0.05) lower in patients with adverse outcomes (0.80±0.32) than in those free from adverse events (1.21±0.43), but volumetric and pressure-adjusted were not (p>0.05). <h3>Conclusion</h3> Functional CT and RHC can be used to derive single-beat measures of coupling and differentiate between patients with and without short-term adverse outcomes.