Abstract Introduction Balloon pulmonary angioplasty (BPA) is a complex procedure and not risk free. In an attempt to standardize reports of BPA complications in the several centers, a classification of complications was proposed by the task force on chronic thromboembolic hypertension (CTEPH) in the 6th World Symposium on Pulmonary Hypertension (WSPH). Purpose To determine the prevalence of BPA complications according to the classification of 6th WSPH and to identify its predictors. Methods Detailed procedural and technical aspects were collected for consecutive patients (pts) with inoperable, residual/recurrent chronic thromboembolic disease, undergoing BPA at a single institution from December/2017 to December/2020. Per procedure logistic regression analysis was used to evaluate the predictive variables for complications. Results A total of 76 BPA sessions in 15 pts were performed (mean age 63.2±14.0 years; 60.0% women; 86.7% CTEPH). Mean pulmonary artery pressure and pulmonary vascular resistance before the first BPA session were 33.1±13.3 mmHg and 4.8±3.2 woods unit, respectively (73.3% of pts under vasodilator therapy). Femoral access was used for all pts. Mean vessels treated per procedure were 4.3±1.9 (324 vessels in total). Webs, subtotal occlusions, ring-like stenosis and total occlusions were noted in 215 (66.4%), 58 (17.9%), 31 (9.6%) and 20 (6.2%) treated vessels, respectively. We performed 21 pressure-wire-guided sessions (27.6%). Intravascular imaging was used in 6 procedures (7.9%). Average time of fluoroscopy was 60.3±14.0 minutes and volume of contrast 273.0±73.0 mL per session. Procedure-related adverse events occurred in 25.0% of the interventions (27.6% in the first two years vs 16.7% in the last two). Pulmonary artery vascular injuries were noted in 6 BPA vessels (7.9% per procedure and 1.9% per treated vessel): haemoptysis in all, but perforation was only detected angiographically in 3 of them (balloon inflation was performed for 2 distal perforations, and 1 perforation sealed without any intervention). Vascular dissection in distal lesions occurred in 4 cases (5.3%) with no need of transcatheter or surgical procedures. We had 3 lung injuries, all grade 2. None of the pts required oral intubation or mechanical ventilation. Extra-pulmonary complications were illustrated in table. Importantly, there was no peri-procedural death. The occurrence of vascular or lung injuries was 0% in pressure-wire-guided BPA versus 14.5% in non-guided (p=0.098). Multivariate analysis revealed that age (OR 1.05; CI 1.01–1.10; p=0.030) was the only independent predictor of complications. Conclusions In our experience, BPA can be safely performed in inoperable, residual or recurrent CTEPH or CTED pts, with 25% minor procedural-related complications but no major adverse event. Age was the strongest factor related to the occurrence of complications. Funding Acknowledgement Type of funding sources: None.

Abstract Introduction Balloon pulmonary angioplasty (BPA) has emerged as a therapeutic option for chronic thromboembolic pulmonary hypertension (CTEPH) considered ineligible for pulmonary endarterectomy (PEA). The initial publications showed very good short-term outcomes for the technique, but there are limited data regarding medium-term outcomes and its comparison with optimal medical treatment (OMT). Objectives To evaluate and compare the medium-term outcomes of OMT versus (vs) BPA in inoperable CTEPH. Methods Retrospective study of consecutive patients (pts) with CTEPH followed in a referral centre for Pulmonary Hypertension. Selected those pts considered ineligible for PEA and with at least 2 years of follow-up. Comparison between two treatment strategies: OMT alone [maximum tolerated doses of pulmonary vasodilator drugs (PVD), as indicated] vs BPA (pts who completed the program with or without OMT). Endpoint was a composite of all-cause death and unplanned right heart failure admission at 2-year. Results From 62 pts, 19 pts were included (11 pts were excluded due to recent diagnosis; 32 were submitted to EAP): mean age 65.0±15.3 years, 89.5% female. At diagnosis, all pts had functional capacity limitation and elevated serum NTproBNP levels (median value 1255.0 pg/mL). Mean pulmonary arterial pressure (mPAP) was 46.2±9.3 mmHg and pulmonary vascular resistance (PVR) 15.3±8.3 Wood units (WU). Concerning treatment, 12 pts (63.2%) underwent OMT alone. These pts had higher NTproBNP levels (2670.0 vs 538.0 pg/mL, p<0.01) and PVR values (19.7±7.6 vs 9.7±5.4 WU, p=0.01) and lower CI (1.6±0.3 vs 2.4±0.5 L/min/m2, p<0.01), at baseline; the remaining basal features didn't differ among groups (Fig.A). At 2-year follow-up, pts submitted to BPA were under PVD in 71.4% of cases with a mean of 1±0.8 drugs per patient and no difference compared to OMT group (83.3%, 1.7±0.9 drugs per patient), although oxygen therapy was higher in medical group (50% vs 0%, p=0.04). A significant overall improvement was observed in BPA group (Table – A): all pts were in functional class I (p<0.01), no one had right ventricular dysfunction (p<0.01) and mPAP decreased to 25.1±6.7 mmHg (p=0.01) and RVP to 2.9±0.8 WU (p=0.01). Inversely, no change was observed in pts under OMT alone (p>0.05 in all, Table – A). Endpoint rate was 31.6% with all adverse events occurring in the OMT group (50% vs 0%, p=0.04). After adjustment by Cox regression, no difference in baseline or follow-up features besides treatment influenced the outcome. Kaplan-Meier analysis (Graphic – B) confirmed significant benefit of BPA in 2-year outcome occurrence (long rank 4.6, p=0.03). Conclusions BPA strategy seems to improve medium-term functional capacity, right ventricular function and haemodynamics and decrease oxygen therapy dependence in inoperable CTEPH. Pts under OMT alone have a poor prognosis. These data encourage the development and implementation of the technique for inoperable CTEPH. Funding Acknowledgement Type of funding sources: None.

Abstract Introduction Percutaneous catheter-directed treatments have emerged at the last decade for the management of acute high- or intermediate-high-risk pulmonary embolism (PE). Good short-term efficacy and safety have been published, but there are limited data regarding medium- to long-term outcomes. Purpose This study aimed to evaluate 1-year all-cause mortality of acute high- and intermediate-high-risk PE patients (pts) treated with continuous aspiration mechanical thrombectomy. Methods Twenty-nine consecutive pts with acute central PE (mean age 67.2±14.4 years; 72.4% female; 24.1% active cancer; Charlson comorbidity index 4.5±2.1; 82.8% in class>III of original PESI score; 44.8% high-risk PE) were treated with the Indigo Mechanical Thrombectomy System (Penumbra, Inc) between 03/2018 and 03/2020. Clinical success was defined as improvement in hemodynamic and/or oxygenation parameters or pulmonary hypertension or right heart strain at 48 hours after intervention plus survival to hospital discharge. Data regarding severe adverse events potentially related to the procedure, in-hospital and 1-year all-cause mortality were collected. Results Clinical success was 75.9%, with a significant improvement in mean paO2/fiO2 ratio (+77.1±103.2; p<0.01), shock index (−0.4±0.4, p<0.01), need for aminergic support (−75.0%, p<0.01), right ventricular function (66.6%, p<0.01) and systolic pulmonary arterial pressure (−10.2±11.5mmHg, p<0.01) at 48 hours after procedure. In-hospital survival rate was 82.8% but severe adverse events potentially related to the procedure occurred in 3 pts (10.3%). One-year follow-up was completed in 93.1% of cases and all-cause mortality rate was 34.5% (n=10 of which half occurred during the index hospital stay). Higher scores of Charlson comorbidity index (5.8±1.9 vs 3.7±1.9, p=0.01) and de novo atrial fibrillation at admission (40% vs 0%, p<0.01) were associated with higher 1-year all-cause mortality occurrence and were identified as 2 independent risk predictors by multivariate Cox regression. Kaplan-Meier curves confirmed its significant influence in 1-year survival free of adverse event (Figure). Time among diagnosis and percutaneous treatment (p=0.99), PESI score (p=0.24) and other clinical, haemodynamic and echocardiographic features did not influence mortality and suggest similarity of the PE severity at baseline. Technical characteristics were also not associated with mortality. Conclusions Aspiration thrombectomy for acute high- and intermediate-high-risk PE was feasible with a high clinical success rate. One-year all-cause mortality rate was elevated and predicted by high comorbidity index and de novo atrial fibrillation at admission. This data support the national expansion of this new PE treatment, but probably and as similar to other invasive techniques, we need to take into account comorbidities and avoid futility in multimorbidity pts. Funding Acknowledgement Type of funding sources: None.

Abstract Introduction The risk of contrast-induced nephropathy (CIN) after left-sided cardiac procedures is reported as 10–15%. When the ratio of total contrast volume in ml to glomerular filtration rate (GFR) in mL/min (ratio V/GFR) exceeds 3.7, the risk increases significantly. However, there are few reports regarding the risk of CIN in patients (pts) with right-sided cardiac interventions such as balloon pulmonary angioplasty (BPA) and ratio V/GFR is not validated for use in this procedures. Purpose To assess the prevalence of CIN in pts with chronic thromboembolic pulmonary disease with or without hypertension (CTEPH/CTED) undergoing BPA. Methods Prospective single-centre study that included all BPA sessions performed from 2017 to 2020. Serum creatinine concentration (SC) was measured and the GFR was estimated using the Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) before and 48 hours after each BPA procedure and 6 months after BPA treatment completion. CIN was defined as an increase of ≥25% and/or ≥0.5 mg/dL in SC from the baseline value within 48h of contrast administration. Results 76 consecutive BPA sessions were performed in 15 CTEPH/CTED pts: mean age 63.2±14.0 years, 60% female, 86.7% CTEPH, mean of 5.3±1.9 sessions per patient with 4.3±1.9 vessels dilated per session. Mean value of GFR before BPA program was 73.5±26.3 mL/min. All the procedures were performed using low-osmolality contrast agent with a 1:1 dilution ratio with normal saline solution. Pts received 273.0±73.0 mL of contrast per session with a ratio V/GFR 3.7±1.7 mL. SC and GFR did not change significantly within 48h after BPA (+3.1%, p=0.07 and −3.0%, p=0.13, respectively). Ratio V/GFR >3.7 occurred in 44.3% of cases (n=31), but CIN occurred in only 5.3% (n=4) with an increase in SC <0.5 mg/dL but ≥25% in 3 cases (+33% in mean) and ≥0.5 mg/dL in 1 case. None of the pts required renal replacement therapy. Higher SC and lower GFR 48h after BPA were significantly correlated with greater rato V/GFR during procedure (r=0.75, p<0.01 and r=−0.74, p<0.01, respectively) – see figure. But neither higher values of ratio V/GFR (OR 1.43; CI95% 0.84–2.41; p=0.19) nor V/GFR >3.7 (OR 1.28; CI95% 0.17–9.6; p=0.81) were predictors of CIN. GFR before procedure did not influence the contrast volume administered (p=0.901), number of vessels (p=0.63) and segments treated by session (p=0.45). At 6 months follow-up, there was a trend for SC (1.3±0.2 mg/dL vs 1.1±0.2 mg/dL, −15%, p=0.43) and GFR (44.5±8.3 mg/dL vs 53.0±12.6 mg/dL, +16%, p=0.34) improvement in pts with impaired renal function at baseline (GFR<60 mL/min). Conclusions These findings suggested that the occurrence of CIN after BPA was low, raising the hypothesis that the influence of contrast agent on renal function could differ in right-sided cardiac interventions. Although the ratio V/GFR may be correlated with the risk of nephropathy, it is necessary to find a new cut-off to predict CIN in BPA pts. Funding Acknowledgement Type of funding sources: None.

Abstract Introduction Atrial septal defects (ASD) may be a cause of pulmonary hypertension (PH) specially when they are only detected in adulthood. Sinus venosus type ASD are rare, with an estimated prevalence of 4-11%, and frequently they are associated with anomalous venous return of the right superior pulmonary vein (RSPV). Surgical closure is safe and effective, and it is associated with normal life expectancy when performed before age 25; the risk of PH is higher in untreated defects or late closure. Clinical case The authors present the case of a 74-years old female patient with previous diagnosis of a sinus venosus type ASD. Closure of the shunt and correction of venous return was performed when the patient was 36. Follow up in the following years was normal, and the patient was discharged from the congenital surgical center. The patient was referred to our PH unit due to symptomatic PH for etiological investigation (PSAP of 70 mmHg in transthoracic echocardiogram). After excluding PH related to left heart disease and lung disease, the most likely cause was pulmonary arterial hypertension due to late closure of left to right shunt, but complete investigation was performed. A transesophageal echocardiogram showed dilatation of right heart chambers and a communication of 36 mm at the high atrial septum between the RSPV and superior vena cava entrance with spontaneous left to right shunt. A severe dilation of coronary sinus (maximal dimension 33.4mm) suggestive of persistent left superior vena cava (PLSVC) was also found. A cardiac magnetic resonance was performed showing dilated right chambers, abnormal drainage of right superior pulmonary vein to right atrium, a dilated coronary sinus with a PLSVC and Qp/Qs 1.7. Right heart catheterization showed a mean pulmonary artery pressure of 25 mmHg with normal pulmonary vascular resistance (2.4 UWood) suggesting that the intracardiac shunt is the responsible for the PH with reversible pulmonary vascular disease. The patient was proposed to surgical repair. Conclusion The authors present a rare clinical case of an undiagnosed persisting sinus venous ASD after surgical repair. Failure of shunt closure led to the development of PH, emphasizing the need to maintain lifelong follow up of these patients in specialized centers. Abstract P694 Figure.

Abstract Introduction Thermodilution (TD) and indirect Fick (IF) methods are widely used to measure cardiac output (CO). They are often used interchangeably to make critical clinical decisions, yet few studies have compared these approaches concerning agreement and comparative prognostic value as applied in medical practice. Purpose To assess agreement between TD and IF methods and to compare how well these methods predict mortality. Methods Retrospective cohort study including all consecutive right heart catheterizations performed in a referral pulmonary hypertension (PH) centre from 2010 to 2018. Cardiac index (CI) was calculated by indexed CO to body surface area. PH was classified according to the new definition of the 6st World Symposium on Pulmonary Hypertension 2018 [mean pulmonary arterial pressure (mPAP) &gt;20 mmHg]. Patients with cardiac or extra-cardiac shunts or significant (moderate to severe or severe) tricuspid regurgitation were excluded. All-cause mortality over 1 year after right heart catheterization was recorded. Logistic regression was used to identify predictors of the adverse event. Results From a total of 569 procedures, 424 fulfilled the inclusion criteria: mean age 56.7±15.4 years, 67.3% female. Haemodynamic parameters were diagnosed of PH in 86.2% of cases: mPAP 35.3±15.3 mmHg, 83.6% pre-capillary subtype, 42.9% belonging to group 4 (chronic thromboembolic pulmonary hypertension) and 26.6% to group 1 (pulmonary arterial hypertension). Mean values of CO and CI were, respectively, 4.5±2.8 L/min and 2.5±0.8 L/min/m2 measured by TD and 4.6±2.4 L/min and 2.6±1.3 L/min/m2 measured by IF method. There was a median difference (IF minus TD) of - 0.03 / min to CO and - 0.05 L/min/m2 to CI but both meausres correlated only modestly (r=0.6 to TD and r=0.5 to IF). One-year all-cause mortality rate was 5.4% (median time to death was 50.5 days). Lower values of CO and CI assessed by TD were significantly associated with all-cause mortality occurrence (CO TD: 4.5±1.3 L/min versus 3.6±1.0 L/min, p&lt;0.01; CI TD: 2.6±0.7 L/min/m2 versus 2.1±0.4 L/min/m2, p&lt;0.01). No association was observed between CO (p=0.31) and CI (p=0.42) measured by IF method and the adverse event. Logistic regression identified 2 independent predictors of all-cause mortality: TD CO (OR 0.55, 95% CI 0.38–0.79, p&lt;0.01) and TD CI (OR 0.34, 95% CI 0.17–0.67, p&lt;0.01). Similar results were obtained when patients diagnosed with PH were independently analyzed. Conclusions There is only modest agreement between TD and IF CO and CI estimates. Despite being more time-consuming, TD measurements were predictors of all-cause mortality and present a highest prognostic value. These findings favored their used over IF in clinical practice. Funding Acknowledgement Type of funding source: None

Abstract A 32 year old female patient, with a medical history of an ill-characterized Pulmonary Arterial Hypertension associated with congenital heart disease, lost in the follow up with no medical therapy, attended an emergency department for a gynecological hemorrhage at 16 weeks of pregnancy. Due to high maternity mortality risk, informed consent was obtained, and termination of pregnancy was performed. She was then referred to our pulmonary hypertension center. At our center she had complains of fatigue with moderate intensity exertion, classified in a class II of the World Health Organization (WHO) classification, but was otherwise asymptomatic, with no history of dyspnea, angina or syncope. There was allusion to a self-limited episode of hemoptysis in the past. On physical examination she had an increased pulmonary component of the second heart sound, continuous heart murmur in left sternal border and no cyanosis (O2 peripheral saturation in the upper and lower limbs of 99% at room air). The performed echocardiograms (both transthoracic and transesophageal) showed an estimated systolic pulmonary artery pressure of 120 mmHg with severe right ventricular hypertrophy and systolic dysfunction. There was dilatation of the trunk and right pulmonary artery. The left pulmonary artery was not seen. Biochemical evaluation and viral serologies were unremarkable. The pulmonary function tests and the arterial blood gases were normal. Cardiac MRI demonstrated the presence of a right aortic arch and a right patent arterial duct. An anomalous origin of the left pulmonary artery from the ascending thoracic aorta could be noted. Associated congenital cardiac defects were excluded. A right heart catheterization confirmed the presence of severe pulmonary hypertension with mean pulmonary artery pressure of 86 mmHg and Pulmonary vascular resistance of 11 Wood Units. A large persistent arterial duct to the right pulmonary artery was confirmed with persistent left to right shunt. The left pulmonary artery was visualized when injection was performed in the aortic root. Coronary arteries were normally implanted. The patient was started on Sildenafil and Bosentan (later replaced by Macitentan due to hepatic toxicity). After 3 years of follow up, there was an improvement in symptoms and in the 6 minutes walking test, remaining in a low risk category and on a WHO class I. This case reports a very rare congenital abnormality identified in an adult patient. Despite the complex anatomy and severe pulmonary hypertension, the patient is reasonably well under medical therapy and close follow up. Abstract P1728 Figure. Cardiac MRI Cine Sequences