Objective Pulmonary artery compliance (PAC), estimated as stroke volume (SV) divided by pulmonary artery pulse pressure (PP), may be a predictor of survival in pulmonary arterial hypertension (PAH). Resistance–compliance (RC) time, the product of PAC and pulmonary vascular resistance, is reported to be a physiological constant. We investigated if differences in PAC and RC time exist between pulmonary hypertension (PH) subgroups and examined whether PAC is an independent predictor of transplant-free survival in PAH.
Methods This was a retrospective analysis of adult PAH (n=532) and chronic thromboembolic PH (CTEPH, n=84) patients enrolled in the US Pulmonary Hypertension Association Registry from 2015 to 2019. PAC and RC time were compared between PH subgroups (connective tissue disease-PAH (CTD-PAH), idiopathic/heritable-PAH (i/h-PAH), drug/toxin-PAH (d/t-PAH)). Cox proportional hazards models were constructed for transplant-free survival, adjusting for REVEAL 2.0 risk score.
Results There were no differences in estimated PAC between PAH subgroups, nor between PAH and CTEPH. RC time was shorter in CTEPH compared with PAH (median 0.55 (IQR 0.45–0.64) vs 0.62 (0.52–0.73) s, p<0.0001). RC time was shortest in CTD-PAH when compared with i/h-PAH and d/t-PAH ((0.59±0.18) vs (0.65±0.20) vs (0.73±0.25) s, p=0.0001). PAC was associated with transplant-free survival (HR 0.72, 95% CI 0.55 to 0.94, p=0.02) but was not an independent predictor of outcome after adjustment for REVEAL 2.0 score.
Conclusion PAC was similar between PH groups and was not an independent predictor of transplant-free survival in PAH. RC time was different between PH subgroups, challenging RC time constancy.
Trial registration number NCT04071327
- Pulmonary Arterial Hypertension
- Pulmonary Embolism
Data availability statement
Data may be obtained from a third party and are not publicly available. At this point, data are only available to the PHAR investigators.
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Contributors Concept/design: AM, AK and MRL; data acquisition: AM, AK and MRL; data analysis/interpretation: AM, AK, MRL, DB, RLB, TMB, TDM, JF, ARH, RH, EH, JK, SCM, WM, SCP, JSS, OAS and MAS; drafting of the manuscript: AM, AK and MRL; critical revision of the manuscript: DB, RLB, TMB, TD, JF, ARH, RH, EH, JK, SCM, WM, SCP, JSS, OAS and MAS. MRL is the guarantor of this manuscript and accepts full responsibility for the work and conduct of the study, had access to the data and controlled the decision to publish.
Funding The Pulmonary Hypertension Association provides funding (no award number available) for the PHAR, which was used for this manuscript.
Disclaimer The Pulmonary Hypertension Association did not have any input regarding the design, conduct or interpretation of study results.
Competing interests ARH: consultant for Bayer, Janssen, United Therapeutics, GossamerBio and Complexa. Holds stock in Tenax Therapeutics. MAS: research support from Novartis. Haemodyanamic core lab for Aadi. Consulting/scientific advisory board for Janssen, Acceleron, Liquidia, Bial, Impulse Dynamics. OAS: consultant and speaker for United Therapeutics, Johnson and Johnson, and Bayer. JSS: research grants from Janssen, PhaseBio, Reata, Bayer, United Therapeutics and Covance. Consultant for Janssen, Bayer and United Therapeutics. TDM: consultant for Actelion/Johnson and Johnson, United Therapeutic, SCIOS-Bial and TrioHealth. Advisory Boards for Altevant and Liquidia; MRL: dlinical trial participation with Gilead, Actelion/Janssen, Bayer, United Therapeutics, Altavant and Acceleron (all funds to the institution).
Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods section for further details.
Provenance and peer review Not commissioned; externally peer reviewed.
Author note Prior abstract: McCormick A, Krishnan A, Badesch DB, et al. Pulmonary Artery Compliance in Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension: The Pulmonary Hypertension Association Registry. American Journal of Respiratory and Critical Care Medicine. 2020;201:A6061
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