BACKGROUND
Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by persistent
and organized pulmonary thrombi and pulmonary hypertension (PH). Right heart catheterization
(RHC) is the gold standard for diagnosis of PH, defined by a resting mean pulmonary
artery pressure (mPAP) > 20 mmHg. Chronic organized thrombi, in the absence of PH
at rest is termed chronic thromboembolic disease (CTED). Pulmonary endarterectomy
(PEA) is indicated for CTEPH, however PEA is not routinely endorsed for CTED. Exercise
is increasingly employed as a provocative maneuver during RHC to elicit abnormalities
of pulmonary vascular and cardiac physiology in patients without PH at rest who are
at risk of pulmonary vascular disease. Exercise RHC may expose abnormalities of pulsatile
or resistive pulmonary vascular afterload in CTED patients and may potentially identify
a subset of CTED patients who benefit from PEA surgery. We describe the proportion
of CTED patients with latent pulmonary vascular hemodynamic abnormalities and their
hemodynamic characteristics.
METHODS AND RESULTS
Consecutive patients with a resting mPAP ≤ 20 mmHg and CTED who completed an exercise
hemodynamic study between November 2016 and September 2020 were included. We defined
exercise abnormalities of pulmonary resistive load as mPAP/CO > 3 WU and exercise
abnormalities of pulsatile load as the ratio of pulmonary pulse pressure to pulmonary
artery wedge pressure (PP/PAWP) > 2.5.
Thirty-seven CTED patients (32% female, 55±15 years) were analyzed. Resting hemodynamics
for the entire cohort and exercise hemodynamics for patients with and without latent
pulmonary vascular abnormalities are shown (Table 1). Twenty-two patients (59%) demonstrated
latent pulmonary vascular abnormalities; 12 had an elevated pulsatile load (PP/PAWP
5.3±4.5), 5 had an elevated resistive load (mPAP/CO 3.7±0.7 WU) and 5 had both (mPAP/CO
3.7±0.5 WU, PP/PAWP 7.3±3.6). Patients with latent pulmonary vascular abnormalities
exercised to lower work-rates (P=0.03) and had lower exercise PAWP (P=0.02). They
were also characterized by higher pulmonary vascular resistance (P < 0.001) and impaired
pulmonary artery compliance (P < 0.001) compared to patients without latent pulmonary
vascular abnormalities.
CONCLUSION
Patients with CTED and resting mPAP ≤ 20mmHg, exercise demonstrated latent abnormal
pulmonary vascular responses in over 50% of patients. These patients predominantly
demonstrated abnormalities of pulsatile afterload relative to resistive afterload.
Further study is required to understand if these patients benefit from PEA surgery.
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© 2021 Published by Elsevier Inc.
