BACKGROUND:Post-thrombotic syndrome is common after deep-vein thrombosis and can cause severe symptoms involving the limbs that impair patients' activity and quality of life. Endovascular therapy can eliminate chronic venous obstruction and is hypothesized to reduce the severity of post-thrombotic syndrome. METHODS:We randomly assigned 225 patients with moderate or severe post-thrombotic syndrome and imaging-confirmed iliac-vein obstruction to receive endovascular therapy (iliac-vein stent placement and enhanced antithrombotic therapy) plus standard post-thrombotic syndrome care or standard post-thrombotic syndrome care alone. The severity of post-thrombotic syndrome at 6 months (the primary outcome) was assessed with the validated Venous Clinical Severity Score (VCSS) tool (scores range from 0 to 30, with higher scores indicating more severe post-thrombotic syndrome) by evaluators who were unaware of the group assignments. Key secondary outcomes included venous disease-specific and overall quality of life. RESULTS:At 6 months, the severity of post-thrombotic syndrome was lower in the endovascular-therapy group than in the no-endovascular-therapy group (mean [±SD] VCSS, 8.1±5.1 vs. 10.0±4.9; adjusted difference, -2.0; P = 0.001). Venous disease-specific quality of life as assessed with the Venous Insufficiency Epidemiological and Economic Study Quality of Life questionnaire was better in the endovascular-therapy group than in the no-endovascular-therapy group at 6 months (adjusted difference, 14.5 points; P<0.001), as was overall quality of life as assessed with the Medical Outcomes Study 36-Item Short-Form Health Status Survey physical component summary score (adjusted difference, 6.1 points; P<0.001); scores on both tools range from 0 to 100. Through 6 months, bleeding was more common in the endovascular-therapy group than in the no-endovascular-therapy group (in 11.6% vs. 3.6% of the patients; P = 0.03). CONCLUSIONS:Among patients with moderate or severe post-thrombotic syndrome and iliac-vein obstruction, endovascular therapy led to less severe post-thrombotic syndrome and better health-related quality of life than standard care over a 6-month period but with a higher risk of bleeding. (Funded by the National Heart, Lung, and Blood Institute and others; C-TRACT ClinicalTrials.gov number, NCT03250247.).

BACKGROUND:Pulmonary vascular obstruction causes dyspnea in chronic thromboembolic pulmonary disease (CTEPD) and chronic thromboembolic pulmonary hypertension (CTEPH). Conventional assessments, like 6-minute walk test (6MWT) and World Health Organization (WHO) functional class (WHO-FC), poorly discriminate the mechanism of dyspnea. Cardiopulmonary exercise testing (CPET) offers direct evaluation of ventilatory efficiency and gas-exchange abnormalities. OBJECTIVES:The purpose of this study was to evaluate the impact of balloon pulmonary angioplasty (BPA) and pulmonary thromboendarterectomy (PTE) on CPET-derived gas-exchange parameters. METHODS:In this prospective study, patients with CTEPD or CTEPH evaluated by a multidisciplinary team underwent outpatient point-of-care CPET (SHAPE-HF system) before and after BPA/PTE. The primary endpoint was change in ventilatory efficiency, assessed by the VE/VCO2 (minute ventilation/carbon dioxide production) slope. Secondary endpoints included changes in WHO-FC and 6MWT. RESULTS:Sixty patients were evaluated; 8 served as controls, and 52 underwent revascularization (20 PTE and 32 BPA). The VE/VCO2 slope improved from 43 to 31 (P < 0.001) after BPA and from 42 to 32 (P = 0.02) after PTE. WHO-FC improved from class III to I in both groups (P < 0.001). The mean 6MWT increased 38 m (381 ± 146 vs 419 ± 151 m; P = 0.03) in the BPA and PTE group (349 ± 162 vs 358 ± 140 m; P = 0.7). VE/VCO2 and Shape-HF Severity Score positively correlated (P < 0.001), but not with 6MWT (P = 0.83). Before and after revascularization, the Shape-HF score improved in the BPA (2.4 vs 1.5; P < 0.001) and the PTE (2.3 vs 1.6; P = 0.01) groups. Survival at 1-year follow-up was a 100%. CONCLUSIONS:Point-of-care CPET provides objective assessment of gas-exchange improvements after pulmonary revascularization in mild-to-moderate CTEPH/CTEPD.

OBJECTIVE:Acute venous thromboembolism (VTE), encompassing deep vein thrombosis and pulmonary embolism, is one of the leading causes of cardiovascular mortality. Recent studies have shown racial and ethnic disparities in VTE incidence and outcomes. The objective of this review is to identify racial and ethnic disparities present in the incidence, diagnosis, and management of VTE. METHODS:A comprehensive review was conducted in PubMed and ScienceDirect using the following search terms: pulmonary embolism, deep vein thrombosis, race, ethnicity, racial disparities, ethnic disparities, and social determinants. Papers were included if they were published in English and within the years 2004 to 2024. Papers were excluded if they studied non-United States adult populations, if VTE was not a main outcome of interest, or if they focused on surgery or COVID-related VTE. The resultant papers (n = 52) included randomized clinical trials, systematic reviews, meta-analyses, and observational studies at single-center, multi-center, and national levels. Quantitative data on the use of catheter-based therapies (CBTs) by racial and ethnic groups were extracted from a subsect of papers where it was explicitly reported (n = 8). Using this data, a meta-analysis was conducted to compare the utilization of CBTs for pulmonary embolism across different racial and ethnic groups. RESULTS:Significant racial and ethnic disparities in the diagnosis and treatment of VTE were noted. Black patients had the highest disease incidence, severity, mortality, and inpatient complications. Similar inequities may exist among other racial and ethnic groups, although these remain less well-characterized due to limited ethnic representation in current VTE literature and related clinical trials. Genetic factors contribute more to VTE risk in White patients, whereas comorbidities and socioeconomic disparities have a more significant impact on non-White patients. Several studies have noted disparities in access to catheter-directed thrombolysis for non-White patients compared with White patients. Notably, racial disparities in advanced therapy usage are reduced in the context of high-risk pulmonary embolism, though ethnic disparities persist. Initial studies have suggested that Pulmonary Embolism Response Team implementation may reduce disparities in VTE management, though further research is needed to evaluate its impact on outcomes. Results of the meta-analysis further supported these findings by revealing increased CBT usage in White and non-Hispanic patients compared with Black and Hispanic patients, respectively. CONCLUSIONS:Socioeconomic vulnerability and comorbid conditions account for disparities in VTE incidence in minority populations, and poor outcomes in these groups may be tied to inequalities in access to catheter-based interventions.

Introduction:Over the past decade, the inpatient management of pulmonary embolism has undergone a paradigm shift in response to new evidence and the adoption of catheter-directed reperfusion therapies. However, real-world practice patterns remain poorly characterized. Methods:This study used Epic's Cosmos database to analyze admissions for pulmonary embolism in the United States between January 1, 2016, and December 31, 2024. Adult inpatient admissions for pulmonary embolism were identified by International Classification of Diseases, Tenth Revision codes documented in the Admit to Inpatient order. Admissions were stratified by severity using established high-risk criteria to allow for a risk-based comparison of treatment strategies. High-risk criteria included the presence of cardiogenic shock, cardiac arrest, the use of vasopressors, dobutamine, extracorporeal membrane oxygenation, or mechanical ventilation at any point during the admission; the remaining admissions were classified as non-high-risk. Trends in patient characteristics, anticoagulation strategies, reperfusion therapies, and cardiopulmonary support were analyzed across the study period. Results:This study identified a total of 267,094 hospital admissions for pulmonary embolism (mean [SD] age, 63 [17] years; 51.4% female; 71.1% White) between 2016 and 2024. Of these admissions, 5.5% met one or more high-risk criteria, increasing from 4.3% in 2016 to 5.8% in 2024 (p < 0.001). The proportion of patients receiving unfractionated heparin alone increased across non-high-risk (33.2% to 63.0%) and high-risk cases (53.7% to 66.3%). Among non-high-risk admissions, the utilization of reperfusion therapies nearly doubled (5.2% to 10.3%, p = 0.002), primarily driven by a rise in the use of catheter-directed embolectomy. In high-risk admissions, the overall use of reperfusion therapies remained stable (27%-34%, p = 0.135), while catheter-directed embolectomy emerged as the predominant modality. For hemodynamic support of high-risk admissions, vasopressor/dobutamine utilization increased (53.3% to 72.2%) as mechanical ventilation use declined (54.7% to 32.4%). Conclusions:These findings help contextualize the extent to which novel therapies and evolving practice patterns have been integrated into real-world care in the United States. Catheter-directed embolectomy has become the dominant reperfusion strategy for pulmonary embolism, reflecting a major shift in practice.

Chronic thromboembolic pulmonary disease (CTEPD) and chronic thromboembolic pulmonary hypertension (CTEPH) are debilitating complications of acute pulmonary embolism (PE) that are characterized by fibrosis and organization of the thrombotic material within pulmonary artery branches. This pathology leads to increased right ventricular afterload and dead space ventilation, posing a risk of progressive pulmonary hypertension, right-sided heart failure, and potentially death if left untreated. Pulmonary endarterectomy (PTE) is a technically complex open-heart surgery considered to be a first-line treatment as it is a potentially curative therapy. Although PTE is highly successful in proximal disease, it may not reach the very distal branches. On the other hand, pulmonary vasodilator therapy is very effective in improving microvasculopathy but does not address the obstructive fibrotic component of the larger vessels. Balloon pulmonary angioplasty (BPA) is a novel percutaneous revascularization therapy in which traditional angioplasty techniques are used to relieve obstruction in the pulmonary arteries. This review discusses the currently accepted indications, patient selection, technical considerations, outcomes, and complications of contemporary BPA. This review will address knowledge gaps and future perspectives in BPA research.

Post-Splenectomy patients are at an increased risk of developing Chronic Thromboembolic Pulmonary Hypertension (CTEPH). We sought to characterize this population. Retrospective chart review of CTEPH patients was conducted and patients with splenectomy were identified and compared to those without. 529 patients with CTEPH were identified and 17 (3.2%) had a history of splenectomy. Of the splenectomy group, they were all White, 5 (29.4%) were female, mean age was 62 ± 12 years, and 7 (41.2%) had red blood cell dyscrasias (i.e. hereditary spherocytosis, thalassemia, and stomatocytosis). Direct oral anticoagulants were used in 15 (88.2%) of the splenectomy patients and 7 (41.2%) were on PH medications. Eight (47.1%) underwent Pulmonary Thromboendarterectomy (PTE), 7 (41.2%) underwent Balloon Pulmonary Angioplasty (BPA) and 1 (5.9%) underwent PTE with subsequent BPA. The mean pulmonary artery (mPA) pressure after intervention was the only significant difference amongst the group receiving BPA vs PTE. For the splenectomy patients who underwent PTE, 6 had segmental disease and 2 had subsegmental disease. Comparing patients with and without splenectomy, there was no significant difference in 6-minute walk (413 ± 147 vs 340 ± 159 meters, p=.08), mean PA (42.5 ± 12.6 vs 43.1 ± 11.8 mmHg, p=0.8), or pulmonary vascular resistance (7.2 ± 3.5 vs 8.2 ± 5, p=0.4). Our findings support the conclusion that post splenectomy patients develop segmental and distal disease.

Introduction: Modified Early Warning Score (MEWS) and National Early Warning Score (NEWS) are scoring systems validated for predicting clinical deterioration and can be trended in electronic medical records over time. Recent studies utilized NEWS as a primary outcome. This study aims to see whether these scores can risk stratify intermediate high-risk pulmonary embolisms (PEs) and predict the necessity of interventions like systemic thrombolysis, catheter-directed directed thrombolysis (CDT), surgical thrombectomy, venoarterial extracorporeal membrane oxygenation (VA-ECMO), and mechanical thrombectomy. Methods: A retrospective chart review identified patients ≥ 18 years old with intermediate-risk PEs at a single hospital between 2017 and 2022. Patients were excluded if they received prior intervention, were transferred from another hospital, had septic PEs, or PE was not their presenting complaint. Of 95 patients, a sample of 20 patients was identified for the intervention and anticoagulation-only groups. MEWS and NEWS were calculated based on presenting vitals. Univariate and multivariate logistical regression were done in STATA. A likelihood ratio test and receiver operating characteristic (ROC) curve analysis evaluated score performance for predicting intervention. Results: In the intervention group, 80% underwent CDT (n=16), 5% (n=1) VA-ECMO, 10% (n=2) surgical thrombectomy, and 15%. (n=3) systemic thrombolysis. The mean NEWS was 3.7 ± 2.61 for the anticoagulation-only group compared to 5.05 ± 2.74 for the intervention group. Similarly, the mean MEWS score was 2 ± 1.41 for the intervention group and 3.25 ± 1.62 for the anticoagulation-only group. Univariate logistic regression showed that each additional point increase in MEWS increased the likelihood of intervention by 1.74 times (p=0.021), with an AUC of 0.7213. The presence of ≥ 2 comorbidities decreased the likelihood of intervention by 78% (p=0.047). There was no association between NEWS and intervention (p= 0.122, AUC= 0.6475). Multivariate analysis found no statistically significant predictors for intervention. Adding the NEWS score to the MEWS score did not significantly improve the prediction of intervention need (p=0.8276) per the likelihood ratio test. Conclusion: This small cohort suggests that MEWS may better predict the need for intervention in intermediate high-risk PE patients than NEWS. When accounting for other variables such as age, comorbidities, and baseline cardiac biomarkers, the predictive value of these scores decreases. However, other studies support the addition of multiple modalities to these scores to improve their predictive accuracy for risk stratification. Further research is needed using a larger sample size (n=262) to be able to detect a statistical difference.

Venous thromboembolism is significantly affected by hormonal and reproductive factors that pose unique challenges in women. Among various risk factors, the role of uterine fibroids, which are the most common benign tumors in women, is not well understood. The relationship between venous thromboembolism and fibroids is mainly attributed to the physical compression caused by large fibroids on pelvic veins, particularly the iliac veins, leading to venous stasis and thrombosis. This review explores the prevalence, pathogenesis, risk factors, possible racial influences, and management strategies of venous thromboembolism associated with fibroids. It highlights the need for better awareness, considering the asymptomatic nature of many fibroids and their potential to lead to serious thromboembolic complications. There is a clear need for screening methods, detailed guidelines, and treatments to prevent such complications and improve women’s health care.

Background: Pulmonary thromboendarterectomy (PTE) remains the preferred treatment for surgical accessible thrombus in patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, residual pulmonary hypertension (PH) can persist post-PTE. Methods: A retrospective single-center analysis of patients that underwent PTE between 2013 and 2023. At 3-month follow-up, we performed a qualitative Echo-Doppler (DE) assessment and applied a semi-quantitative DE scoring system (DESS), assigning point values for six DE parameters: right ventricle (RV) size, RV shape (systolic base–apex ratio), RV function, septal position, tricuspid regurgitation (TR) and RV outflow tract notching (RVOTN). Higher scores suggested a more significant residual PH syndrome. Results: A total of 188 subjects (80%) did not require further PH intervention at ≥3 months (Group A); 48 (20%) required ongoing PH treatment (Group B). The pre-PTE median DESS was 10 and the post-PTE median DESS was 3.00 (range 0–16). The maximum DESS was 17. Using ROC analysis, post-PTE DESS strongly discriminated between Group A and B (AUC 0.76; 95% CI 0.65–0.89; p < 0.001). A post-PTE DESS of >6.5 differentiated Group A and B. Evidence of TR (OR 0.191, CI 0.103–0.279; p < 0.0001) and RV enlargement (OR 0.242; CI 0.153–0.330; p < 0.0001) at follow-up was associated with a need for additional PH interventions. Conclusions: Serial DE examination is a viable, noninvasive method to assess significant residual PH post-PTE.

Since the publication of the first case series reporting the outcomes of patients with chronic thromboembolic pulmonary hypertension who underwent treatment with balloon pulmonary angioplasty more than 30 years ago, significant improvements to the procedural technique have made balloon pulmonary angioplasty (BPA) a safe and effective therapy that we know today. Nevertheless, BPA carries a small risk of complications, which require rapid recognition and immediate management. The most commonly seen complications associated with BPA include pulmonary vascular injury and reperfusion pulmonary edema.

Background: Sarcopenia, or loss of skeletal muscle mass, has been associated with poor outcomes (e.g., functional decline, increased mortality, and low quality of life), but its role in CTEPH remains unclear. The psoas muscle index (PMI) is a validated measure of sarcopenia. We investigated the incidence of sarcopenia using PMI in CTEPH. Methods: Retrospective analysis of a single-center cohort of patients with CTEPH with an available computed tomography of the abdomen and pelvis (CTAP). PMI was measured at the L3 level of the CTAP and was then calculated using the formula (left psoas area + right psoas area/height2). Patients in the first quartile of PMI were classified as sarcopenic. Results: We reviewed 558 patients with CTEPH, and 97 patients had an available CTAP before intervention. Sarcopenia was identified in 26 (24.8%) of the patients and was associated with worse baseline functional status (p = 0.008), higher mean pulmonary artery pressure (48 vs. 39 mmHg; p = 0.002), and higher pulmonary vascular resistance (9.9 vs. 6.8 WU; p = 0.013). Post-PTE, patients with sarcopenia exhibited longer intensive care unit (ICU) (9 vs. 4 days, p < 0.001) and overall hospital stays (24 vs. 11 days, p < 0.001), despite similar post-operative hemodynamics achieved compared to non-sarcopenic patients. Conclusions: CTEPH patients with sarcopenia have worse baseline functional class and hemodynamics. For those with sarcopenia requiring surgery, there is longer ICU and total hospitalization stays, but they achieve significant functional improvements and hemodynamics comparable to that of non-sarcopenic patients. Hence, the risk of longer perioperative hospitalization days is justified by the longer-term benefit of hemodynamic improvement. The use of PMI as part of routine pre-operative assessments could improve clinical decision-making in CTEPH patients undergoing surgical or medical intervention.

Background: The incidence and predictors of intracranial hemorrhage (ICH) in patients with acute myocardial infarction (AMI) complicated by cardiogenic shock (AMI-CS) remain unclear. Objectives: To determine the incidence of ICH in AMI-CS patients and validate a risk score for predicting ICH in this population. Methods: Patients with AMI-CS were identified using ICD-10 codes from January 2016 to December 2019 in the U.S. Nationwide Readmissions Database, and were stratified by the incidence of ICH. Independent predictors of ICH were identified using multivariate logistic regression in the derivation cohort. Based on these predictors, the ICHcal risk score was developed, which was validated in a validation cohort using receiver operating characteristic curves. Results: Among 84,615 patients with AMI-CS, 608 (0.72%) experienced ICH. Of patients treated with mechanical circulatory support (MCS) devices, 162 experienced intracranial hemorrhage, corresponding to an overall incidence of 1.72%. The incidence of ICH in patients with MCS was 1.13% in 2016 and rose over time, with a marked increase between 2017 and 2018 (from 1.14% to 2.24%, P=0.02). Predictors of ICH included: VA-ECMO (OR 9.08, 95% CI 4.61-17.89, P<0.001), ischemic stroke (OR 5.21, 95% CI 3.81-7.14, P<0.001), thrombophilia (OR 2.27, 95% CI 1.68-3.07, P<0.001), microaxial MCS (OR 2.03, 95% CI 1.58-2.60, P<0.001), sepsis (OR 2.01, 95% CI 1.60-2.52, P<0.001), thrombolysis (OR 1.99, 95% CI 1.25-3.18, P<0.004), AKI (OR 1.61, 95% CI 1.30- 1.98, P<0.001), and age <65 years (OR 1.27, 95% CI 1.05-1.54, P<0.015). The ICHcal risk score, developed from these predictors, demonstrated a C-statistic of 0.69 in the derivation cohort and 0.72 in the validation cohort. Conclusion: Patients with AMI-CS have a higher incidence of ICH, particularly those with MCS, compared to patients with AMI alone. A higher ICHcal risk score predicts a higher risk of ICH in these patients and may inform the degree of anticoagulation used to reduce this risk.

BACKGROUND Chronic thromboembolic pulmonary hypertension results from mechanical obstruction of major pulmonary artery lumina with fibrotic tissue. Main treatment has been pulmonary endarterectomy, a complex surgical procedure removing vascular obstruction. However, at least 40% of patients are not candidates for pulmonary endarterectomy because of technical inoperability, comorbidities, or limited access to surgery. Balloon pulmonary angioplasty (BPA) has emerged as an interventional treatment for these patients. OBJECTIVES The International BPA Registry (NCT03245268) was designed to investigate BPA practice across 18 established centers in the United States, Europe, and Japan. METHODS A total of 500 patients were prospectively and consecutively enrolled between March 2018 and March 2020, with follow-up until March 2022. Of these, 484 patients were included in the analysis set. RESULTS Regional differences were seen in patient characteristics (fewer patients with prior pulmonary endarterectomy and more elderly women in Japan) and procedural details (less medical pretreatment, more jugular access, more segments and more occlusive lesions treated per session and patient, less conscious sedation, less contrast and less radiation, shorter intervals between BPA sessions in Japan). Female sex, procedure in Europe/United States, pulmonary hypertension medications at any time, and higher baseline pulmonary vascular resistance (PVR), calculated as trans-pulmonary pressure gradient divided by cardiac output, emerged as independent predictors of complications during BPA. After a median of 5 (Q1-Q3: 3-6) BPA sessions per patient within a median time of 4.9 months (Q1-Q3: 1.7-11.0 months), a 15-mm Hg (38%) decrease in mPAP, a 332 dynes/s/cm-5 (57%) decrease in PVR, and a 3.2% increase in arterial saturation (medians; P < 0.001) were observed, and there were significant improvements in functional class, 6-minute walk distance, serum levels of N-terminal probrain natriuretic peptide, and Borg dyspnea index. BPA complications occurred in 11.3% of sessions and 33.9% of patients and were mostly hemoptyses. No patient died within 30 days of BPA. CONCLUSIONS Our data are in line with previous reports on changes of clinical and hemodynamic parameters and complication rates of BPA. Centers with more experience providing BPAs were more likely to achieve a higher percentage decrease in PVR.

Background: Acute pulmonary embolism (PE) is a leading cause of morbidity and mortality. Pharmacomechanical lysis (PML) with the Bashir endovascular catheter has been shown to reduce the right ventricular/left ventricular (RV/LV) ratio in patients with intermediate-risk (IR) PE. Nevertheless, the original protocol required a 5-hour postprocedural infusion of recombinant tissue plasminogen activator (r-tPA) and intensive care unit monitoring. Objectives: The RESCUE-II (Safety and Feasibility of On-The-Table Pharmacomechanical Lysis for Acute Intermediate-Risk Pulmonary Embolism) study aimed to evaluate the safety and efficacy of on-the-table PML using bolus-only r-tPA, without postprocedural infusion, in patients with IR-PE. Methods: In this single-center, prospective study, symptomatic patients with IR-PE (computed tomographic–derived RV/LV ratio ≥0.9) were treated with bolus-only r-tPA via the Bashir catheter (4 mg per lung, 8 mg total for bilateral PE). The primary efficacy endpoint was the change in RV/LV ratio at 48 hours, and the primary safety endpoint was major bleeding within 72 hours. Results: Nine patients were enrolled and successfully treated. The median procedure time was 39 ± 13.4 minutes. At 48 hours, the mean RV/LV ratio decreased from 1.66 ± 0.56 to 1.27 ± 0.41 (P = 0.0001), and pulmonary artery obstruction, measured by the Refined Modified Miller index, reduced by 29.2%. There were no major bleeding events. One patient had a minor access site hematoma, managed with manual compression. Conclusions: On-the-table PML using the Bashir catheter effectively reduced RV/LV ratio and PA obstruction. The procedure was safe, with no major bleeding complications, and offers a rapid, cost-effective treatment option for patients with acute IR-PE.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a complication of incomplete resolution of acute pulmonary embolism. We hypothesize changes in CT Hounsfield Unit gradient (HU-Δ) created by the dispersion of IV contrast through the downstream blood pool correlate with cardiac index (CI). We sought to compare HU-Δ with invasively obtained CI. Methods: We completed a retrospective analysis of CTEPH patients in which individuals with low CI (<2.2-L/min/m2) were identified. Both absolute and fractional HU-Δ were derived from pulmonary CTA by subtracting the HU value of the left atrium (LA) and left ventricle (LV) from the main pulmonary artery (MPA) (absolute) and expressing them as a percentage of MPA-HU (fractional) on static axial images. These were compared between low and normal CI. Results: Of the 237 patients, 50.2% were female, 53.2% were White, 36.7% were Black. Hemodynamics were mean pulmonary artery (PA) pressure = 45.4 ± 11.2-mmHg, pulmonary vascular resistance = 9.2 ± 4.4-WU, CI = 2.05 ± 0.48-L/min/m2. There was a higher mean MPA-HU = 391.1 ± 113.6 than LA-HU = 251.6 ± 81. In patients with low CI, the HU-Δ was higher, HU-ΔMPA-LA was 148.9 ± 78.4 vs. 124.5 ± 77.2 (p = 0.02), and HU-ΔMPA-LV was 170.7 ± 87 vs. 140 ± 82 (p = 0.009). A HU-ΔMPA-LA = 118 had a sensitivity of 75.6% and specificity of 77% to detect low CI, AUC 0.61, p = 0.003. A HU-ΔPA-LV = 156 had a sensitivity of 77% and specificity of 53% to detect low CI, AUC = 0.62, p = 0.001. A fractional reduction HU-ΔMPA-LA of 35% had a sensitivity and specificity of 79% and 53%, respectively, to detect low CI (AUC 0.65, p < 0.001). A fractional reduction of the HU-ΔMPA-LV of 40% had a sensitivity and specificity of 80% and 55%, respectively, to detect low CI (AUC 0.65, p < 0.001). HU Δ were highly reproducible (Kappa = 0.9, p < 0.001, 95% CI 0.86–0.95). Conclusions: High HU Δ between MPA-LA and MPA-LV were associated with low CI in patients with CTEPH.