Mitral Valve Transcatheter Edge-to-Edge Repair: 1-Year Outcomes From the MiCLASP Study.

BACKGROUND: Mitral transcatheter edge-to-edge repair (M-TEER) is a guideline-recommended treatment option for patients with severe symptomatic mitral regurgitation (MR). Outcomes with the PASCAL system in a post-market setting have not been established. OBJECTIVES: The authors report 30-day and 1-year outcomes from the MiCLASP (Transcatheter Repair of Mitral Regurgitation with Edwards PASCAL Transcatheter Valve Repair System) European post-market clinical follow-up study. METHODS: Patients with symptomatic, clinically significant MR were prospectively enrolled. The primary safety endpoint was clinical events committee-adjudicated 30-day composite major adverse event rate and the primary effectiveness endpoint was echocardiographic core laboratory-assessed MR severity at discharge compared with baseline. Clinical, echocardiographic, functional, and quality-of-life outcomes were assessed at 1 year. RESULTS: A total of 544 patients were enrolled (59% functional MR, 30% degenerative MR). The 30-day composite major adverse event rate was 6.8%. MR reduction was significant from baseline to discharge and sustained at 1 year with 98% of patients achieving MR ≤2+ and 82.6% MR ≤1+ (all P < 0.001 vs baseline). One-year Kaplan-Meier estimate for survival was 87.3%, and freedom from heart failure hospitalization was 84.3%. Significant functional and quality-of-life improvements were observed at 1 year, including 71.6% in NYHA functional class I/II, 14.4-point increase in Kansas City Cardiomyopathy Questionnaire score, and 24.2-m improvement in 6-minute walk distance (all P < 0.001 vs baseline). CONCLUSIONS: One-year outcomes of this large cohort from the MiCLASP study demonstrate continued safety and effectiveness of M-TEER with the PASCAL system in a post-market setting. Results demonstrate high survival and freedom from heart failure hospitalization, significant and sustained MR reduction, and improvements in symptoms, functional capacity, and quality of life.

Ten Future Challenges in the Field of Transcatheter Mitral Valve Edge-to-Edge Repair.

Mitral valve transcatheter edge-to-edge repair (M-TEER) and replacement (TMVR) have evolved as guideline-recommended treatment approaches for mitral regurgitation (MR). Even though they are supported by a growing body of evidence from either randomized trials or large registries, there are still several unsolved challenges in the field of interventional MR treatment. In the present review, we discuss the ten most important open questions regarding M-TEER and TMVR.

Applying the TRILUMINATE Eligibility Criteria to Real-World Patients Receiving Tricuspid Valve Transcatheter Edge-to-Edge Repair.

BACKGROUND: According to the TRILUMINATE (Clinical Trial to Evaluate Cardiovascular Outcomes in Patients Treated With the Tricuspid Valve Repair System) trial, transcatheter tricuspid edge-to-edge repair (T-TEER) improves quality of life beyond medical treatment, while no effects on heart failure hospitalization (HFH) and survival were observed at 1 year. However, the generalizability of the TRILUMINATE trial to real-world conditions remains a subject of discussion. OBJECTIVES: The aim of this study was to apply the clinical TRILUMINATE inclusion and exclusion criteria to a real-world T-TEER patient group and evaluate symptomatic and survival outcome in TRILUMINATE-eligible and TRILUMINATE-ineligible patients. METHODS: Clinical TRILUMINATE inclusion and exclusion criteria were applied to a cohort of patients who underwent T-TEER at 5 European centers from 2016 to 2022. Study patients were compared regarding baseline characteristics, survival, HFH, and symptomatic outcomes as measured by NYHA functional class, a quality-of-life questionnaire and 6-minute walk distance. RESULTS: Of 962 patients, 54.8% were classified as TRILUMINATE eligible, presenting with superior left ventricular function and fewer comorbidities compared with the ineligible population. Tricuspid regurgitation reduction, improvement in NYHA functional class, quality of life, and exercise capacity were comparable in both groups. However, the 1-year survival and HFH rates significantly differed (tricuspid regurgitation ≤2+ at discharge, 82% vs 85%; survival, 85% vs 75%; HFH, 14% vs 22% for eligible vs ineligible patients). CONCLUSIONS: The observed differences in survival and HFH outcomes suggest a limited generalizability of TRILUMINATE to real-world conditions and indicate the need for additional studies evaluating the outcomes after T-TEER in less selected patient populations.

Echocardiographic Outcomes With Transcatheter Edge-to-Edge Repair for Degenerative Mitral Regurgitation in Prohibitive Surgical Risk Patients.

BACKGROUND: The CLASP IID randomized trial (Edwards PASCAL TrAnScatheter Valve RePair System Pivotal Clinical Trial) demonstrated the safety and effectiveness of the PASCAL system for mitral transcatheter edge-to-edge repair (M-TEER) in patients at prohibitive surgical risk with significant symptomatic degenerative mitral regurgitation (DMR). OBJECTIVES: This study describes the echocardiographic methods and outcomes from the CLASP IID trial and analyzes baseline variables associated with residual mitral regurgitation (MR) ≤1+. METHODS: An independent echocardiographic core laboratory assessed echocardiographic parameters based on American Society of Echocardiography guidelines focusing on MR mechanism, severity, and feasibility of M-TEER. Factors associated with residual MR ≤1+ were identified using logistic regression. RESULTS: In 180 randomized patients, baseline echocardiographic parameters were well matched between the PASCAL (n = 117) and MitraClip (n = 63) groups, with flail leaflets present in 79.2% of patients. Baseline MR was 4+ in 76.4% and 3+ in 23.6% of patients. All patients achieved MR ≤2+ at discharge. The proportion of patients with MR ≤1+ was similar in both groups at discharge but diverged at 6 months, favoring PASCAL (83.7% vs 71.2%). Overall, patients with a smaller flail gap were significantly more likely to achieve MR ≤1+ at discharge (adjusted OR: 0.70; 95% CI: 0.50-0.99). Patients treated with PASCAL and those with a smaller flail gap were significantly more likely to sustain MR ≤1+ to 6 months (adjusted OR: 2.72 and 0.76; 95% CI: 1.08-6.89 and 0.60-0.98, respectively). CONCLUSIONS: The study used DMR-specific echocardiographic methodology for M-TEER reflecting current guidelines and advances in 3-dimensional echocardiography. Treatment with PASCAL and a smaller flail gap were significant factors in sustaining MR ≤1+ to 6 months. Results demonstrate that MR ≤1+ is an achievable benchmark for successful M-TEER. (Edwards PASCAL TrAnScatheter Valve RePair System Pivotal Clinical Trial [CLASP IID]; NCT03706833).

Two-Year Outcomes for Tricuspid Repair With a Transcatheter Edge-to-Edge Valve Repair From the Transatlantic TRILUMINATE Trial.

BACKGROUND: Tricuspid regurgitation (TR) is a common and progressive valve disease with significant mortality and hospitalization burden. Tricuspid transcatheter edge-to-edge repair provides a treatment option for high-risk patients with primary and secondary TR. METHODS: The TRILUMINATE trial ([Trial to Evaluate Treatment With Abbott Transcatheter Clip Repair System in Patients With Moderate or Greater Tricuspid Regurgitation]; n=85) is an international, prospective, single-arm, multicenter study to investigate the safety and performance of tricuspid transcatheter edge-to-edge repair with the TriClip implant in patients with symptomatic moderate or greater TR. Echocardiographic assessment was performed at a core laboratory. Outcomes included safety and clinical effectiveness and echocardiographic assessment of TR. RESULTS: At 2 years, TR was reduced to moderate or less in 60% of subjects, and reduction of at least 1 grade was achieved in 85.4% of subjects. TR reduction was sustained in 75% of the patients. While most metrics suggest the majority of favorable remodeling occurred within the first 30 days post-procedure, both right ventricular end diastolic diameter and tricuspid annular plane systolic excursion show signals of continued favorable remodeling through 2 years. Substantial improvements in 6-minute walking distance, New York Heart Association functional class, and Kansas City Cardiomyopathy Questionnaire score were sustained from 30 days to 2 years. Even with low rates of cardiovascular mortality (15.3%) and all-cause mortality (18.7%) noted at 2 years, all-cause hospitalization rate decreased from 1.30 events per patient-year 1 year before device implantation to 0.66 events per patient-year 2 years after the TriClip procedure, representing a reduction of 49% (P<0.0001). CONCLUSIONS: Tricuspid transcatheter edge-to-edge repair using the TriClip implant was found to be safe and effective, with sustained benefits at 2 years in subjects with symptomatic moderate or greater TR. Repair efficacy was durable at 2 years in 75% of the patients. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT03227757.

Cardio-hepatic syndrome in patients undergoing transcatheter aortic valve replacement.

BACKGROUND: Cardiohepatic syndrome (CHS) has been identified as an important but underrecognized survival predictor in multiple cardiovascular disease entities. The objectives of this study were to evaluate the prevalence and prognostic value of CHS in patients undergoing TAVR for severe aortic stenosis (AS). METHODS: The study included patients with available laboratory parameters of hepatic function who underwent TAVR from July 2013 until December 2019 at our center. CHS was defined as an elevation of at least two of three laboratory cholestasis parameters above the upper limit of normal (bilirubin, alkaline phosphatase, and gamma glutamyl transferase). Study endpoints were three-year survival, technical and device failure (VARC 3), as well as New York Heart Association (NYHA) functional class at follow-up. RESULTS: Among a total of 953 analyzed patients (47.6% females, median age 80.0 [76.0-85.0] years) CHS was present in 212 patients (22.4%). In patients with vs. without CHS, rates of technical (6.1% vs. 8.4%, p = 0.29) and device failure (18.9% vs. 17.3%, p = 0.59) were comparable. NYHA functional class at baseline and follow-up was more severe in patients with CHS. Nevertheless, heart failure symptoms improved from baseline to follow-up irrespective of hepatic function. Three-year survival rates were significantly lower in patients with CHS (49.4 vs. 65.4%, p < 0.001). The predictive value of CHS persisted after adjustment in a multivariable analysis (hazard ratio 1.58, p < 0.01). CONCLUSION: In patients undergoing TAVR, CHS is prevalent in 22% of patients and is associated with increased postinterventional mortality. Thus, CHS should be included in the decision-making process within the TAVR heart team. Cardiohepatic syndrome (CHS) as defined by an elevation of at least two of three laboratory cholestasis parameters above the upper limit of normal was prevalent in 22% of patients undergoing TAVR for severe AS. The presence of CHS was associated with more severe heart failure symptoms and worse three-year survival.

Cardio-hepatic syndrome in patients undergoing mitral valve transcatheter edge-to-edge repair.

AIMS: The impact of the cardio-hepatic syndrome (CHS) on outcomes in patients undergoing mitral valve transcatheter edge-to-edge repair (M-TEER) for relevant mitral regurgitation (MR) is unknown. The objectives of this study were three-fold: (i) to characterize the pattern of hepatic impairment, (ii) to investigate the prognostic value of CHS, and (iii) to evaluate the changes in hepatic function after M-TEER. METHODS AND RESULTS: Hepatic impairment was quantified by laboratory parameters of liver function. In accordance with existing literature, two types of CHS were distinguished: ischaemic type I CHS (elevation of both transaminases) and cholestatic type II CHS (elevation of two out of three parameters of hepatic cholestasis). The impact of CHS on 2-year mortality was evaluated using a Cox model. The change in hepatic function after M-TEER was assessed by laboratory testing at follow-up. We analysed 1083 patients who underwent M-TEER for relevant primary or secondary MR at four European centres between 2008 and 2019. Ischaemic type I and cholestatic type II CHS were observed in 11.1% and 23.0% of patients, respectively. Predictors for 2-year all-cause mortality differed by MR aetiology. While in primary MR cholestatic type II CHS was independently associated with 2-year mortality, ischaemic CHS type I was an independent mortality predictor in secondary MR patients. At follow-up, patients with MR reduction ≤2+ (obtained in 90.7% of patients) presented with improved parameters of hepatic function (median reduction of 0.2 mg/dl, 0.2 U/L and 21 U/L for bilirubin, alanine aminotransferase and gamma-glutamyl transferase, respectively, p < 0.01). CONCLUSIONS: The CHS is frequently observed in patients undergoing M-TEER and significantly impairs 2-year survival. Successful M-TEER may have beneficial effects on CHS.

Factors Associated with Progression of Atrial Fibrillation and Impact on All-Cause Mortality in a Cohort of European Patients.

BACKGROUND: Paroxysmal atrial fibrillation (AF) may often progress towards more sustained forms of the arrhythmia, but further research is needed on the factors associated with this clinical course. METHODS: We analyzed patients enrolled in a prospective cohort study of AF patients. Patients with paroxysmal AF at baseline or first-detected AF (with successful cardioversion) were included. According to rhythm status at 1 year, patients were stratified into: (i) No AF progression and (ii) AF progression. All-cause death was the primary outcome. RESULTS: A total of 2688 patients were included (median age 67 years, interquartile range 60-75, females 44.7%). At 1-year of follow-up, 2094 (77.9%) patients showed no AF progression, while 594 (22.1%) developed persistent or permanent AF. On multivariable logistic regression analysis, no physical activity (odds ratio [OR] 1.35, 95% CI 1.02-1.78), valvular heart disease (OR 1.63, 95% CI 1.23-2.15), left atrial diameter (OR 1.03, 95% CI 1.01-1.05), or left ventricular ejection fraction (OR 0.98, 95% CI 0.97-1.00) were independently associated with AF progression at 1 year. After the assessment at 1 year, the patients were followed for an extended follow-up of 371 days, and those with AF progression were independently associated with a higher risk for all-cause death (adjusted hazard ratio 1.77, 95% CI 1.09-2.89) compared to no-AF-progression patients. CONCLUSIONS: In a contemporary cohort of AF patients, a substantial proportion of patients presenting with paroxysmal or first-detected AF showed progression of the AF pattern within 1 year, and clinical factors related to cardiac remodeling were associated with progression. AF progression was associated with an increased risk of all-cause mortality.

Indocyanine green clearance predicts outcome in patients undergoing transcatheter valve intervention for severe atrio-ventricular valve regurgitation.

OBJECTIVES: Severe mitral regurgitation (MR) and tricuspid regurgitation (TR) aggravate haemodynamic stress leading to congestive heart failure with impaired hepatic function, also known as cardiohepatic syndrome (CHS). Current perioperative risk calculators do not sufficiently consider CHS and serum liver function parameters lack sensitivity to diagnose CHS. Indocyanine green and its elimination (measured by the LIMON® test) represent a dynamic and non-invasive test which correlates with the hepatic function. Nevertheless, its utility in the setting of transcatheter valve repair/replacement (TVR) to predict CHS and outcome remains unknown. METHODS: We analysed liver function and outcomes of patients undergoing TVR for MR or TR between August 2020 and May 2021 at the Munich University Hospital. RESULTS: Out of a total of 44 patients treated at the University Hospital of Munich, 21 (48%) were treated for severe MR, 20 (46%) for severe TR and 3 (7%) for both diseases. Procedural success defined as MR/TR ≤2+ was 94% among MR patients and 92% among TR patients. While classical serum liver function parameters did not change after TVR, there was a significant improvement in liver function as assessed by the LIMON® test (P ≤ 0.001). Patients with baseline indocyanine green plasma disappearance rate <12.95%/min showed significantly increased 1-year mortality (hazard ratio: 1.54, 95% confidence interval: 1.05-2.25, P = 0.027) and lower New York Hear Association class improvement (P = 0.05). CONCLUSIONS: Especially in the context of the recently stressed importance of a careful patient selection prior to the interdisciplinary treatment of valvular heart disease, the LIMON® test may provide further real-time information on the patients' cardiohepatic injury and prognosis.

TAVI for patients with normal-flow low-gradient compared to high-gradient aortic stenosis.

BACKGROUND: Normal-flow (stroke volume index, SVi >35 ml/m2) low-gradient (dPmean <40 mmHg) aortic stenosis (NFLG-AS) is subject of scientific debate. Guidelines fail to give conclusive treatment recommendations. We hypothesized that NFLG patients are heterogenous, containing a subgroup similar to high-gradient aortic stenosis patients (dPmean ≥40 mmHg, HG-AS) concerning characteristics and outcomes. METHODS: 2326 patients undergoing transcatheter aortic valve replacement (TAVI) at our centre between 2013 and 2019 were analysed. 386 patients fulfilled criteria of NFLG-AS. Their median dPmean was 33 mmHg, which was used for grouping (204 patients with higher gradient NFLG-AS, 186 patients with lower gradient NFLG-AS). They were compared to 956 HG-AS patients. RESULTS: Characteristics of lower gradient NFLG-AS patients differed from HG-AS patients in many aspects while higher gradient NFLG-AS and HG-AS patients were mostly similar, underscored by higher Society of Thoracic Surgeons scores in lower gradient NFLG-AS (lower gradient NFLG-AS, 3.9, HG-AS, 3.0, p = 0.03, higher gradient NFLG-AS, 3.0, p = 0.04). Procedural complications were comparable. Estimated 3-year all-cause mortality was higher in lower gradient NFLG-AS compared to HG-AS patients (hazard ratio 1.7, p < 0.01), whereas mortality of higher gradient NFLG-AS was similar to HG-AS patients (hazard ratio 1.2, p = 0.31). Cardiovascular mortality was highest among lower gradient NFLG-AS patients (21.6% vs. higher gradient NFLG-AS, 15.4%, vs. HG-AS, 11.1%, p < 0.01). CONCLUSIONS: NFLG-AS patients are indeed heterogenous. NFLG-AS patients with higher gradients resemble HG-AS patients in clinical characteristics and outcomes and should not be treated differently. Lower gradient NFLG-AS patients have increased long-term mortality and the use of TAVI requires careful consideration.

Transcatheter edge-to-edge mitral valve repair in mitral regurgitation: current status and future prospects.

INTRODUCTION: Mitral regurgitation (MR) is associated with substantial morbidity and mortality. Within the past 15 years, mitral valve edge-to-edge repair (M-TEER) has developed from an experimental approach to a guideline-recommended, safe, and effective treatment option for patients with severe primary or secondary mitral regurgitation. AREAS COVERED: This review covered relevant publications of M-TEER and summarizes the development of M-TEER devices within the last 15 years. It outlines anatomical challenges which drove the evolution of M-TEER devices, provides an overview about the current state of clinical application and research, and offers an outlook into the future of transcatheter mitral valve treatment. EXPERT OPINION: The development and refinement of new M-TEER device generations offer the possibility to treat a wide range of mitral valve anatomies. Choosing the best device for the individual anatomic properties of the patients and considering comorbidities is the key to maximized MR reduction, minimalized complication rates, and thus optimized postinterventional prognosis. Independent from prognostic implications, quality of life has become an important patient-centered outcome that can be improved by M-TEER in virtually all patients treated.

Sex-specific impact of anthropometric parameters on outcomes after transcatheter edge-to-edge repair for secondary mitral regurgitation.

BACKGROUND: Body surface area (BSA) has been reported to be the stronger predictor for prognosis than body mass index in heart failure (HF) patients. The sex-specific association of BSA with mortality has been unclear. METHODS: EuroSMR, a European multicenter registry, included patients who underwent edge-to-edge repair (TEER) for secondary mitral regurgitation (SMR). The outcome was two-year all-cause mortality. RESULTS: The present cohort included 1594 HF patients (age, 74 ± 10 years; male, 66%). Association of calculated BSA with two-year all-cause mortality was evaluated. Patients were classified into three BSA groups: the lowest 10% (S), the highest 10% (L), and intermediate between S and L (M). Mean BSA was 1.87 ± 0.21 m2 (male, 1.94 ± 0.18 m2; female, 1.73 ± 0.18 m2). The association of BSA with the endpoint in females showed a U-shaped curve, indicating worse prognosis for both S and L. The association in males followed a linear regression, demonstrating better prognosis for L. Hazard ratio (HR) of L to S in males was 0.43 (95% confidence interval [CI], 0.25-0.74; p = 0.002), whereas HR of L to M in females was 1.76 (95% CI, 1.11-2.78; p = 0.016) (p for interaction = 0.003). CONCLUSIONS: Sex-specific association patterns demonstrate the complex influence of anthropomorphic factors in HF patients scheduled for TEER. Further investigation beyond simple evaluation of weight and height is needed for better comprehension of the obesity paradox and better prediction of the results of transcatheter therapy in HF patients.

Simplified ELASTA-CLIP Before Transapical Mitral Valve Replacement.

Residual and recurrent mitral regurgitation after transcatheter edge-to-edge repair are therapeutically challenging. In the present case report, we describe a simplified, transapical electrosurgical laceration and stabilization of clip procedure that represents an alternative and direct approach for electrosurgical laceration of mitral valve leaflets enabling transcatheter mitral valve replacement for recurrent mitral regurgitation after mitral valve transcatheter edge-to-edge repair.

Successful Transcatheter Closure of Iatrogenic Mitral Regurgitation After Aortic Valve Surgery.

We present 2 cases of significant mitral regurgitation secondary to pericardial patch avulsion from the anterior mitral valve leaflet after aortic valve replacement with aortic annulus enlargement. Both cases were successfully managed by transcatheter repair with off-label implantation of occluder devices.

Heterotopic Transcatheter Tricuspid Valve Replacement in a Patient With Carcinoid Heart Disease.

Neuroendocrine tumors can lead to carcinoid heart disease with subsequent development of severe tricuspid regurgitation due to thickening and restriction of the tricuspid leaflets. We present a patient who underwent successful heterotopic transcatheter tricuspid valve replacement for torrential tricuspid regurgitation due to carcinoid heart disease. (Level of Difficulty: Intermediate.).

Transcatheter valve repair of tricuspid regurgitation with the PASCAL system: TriCLASP study 30-day results.

BACKGROUND: Severe tricuspid regurgitation (TR) is independently associated with increased morbidity and mortality. Percutaneous transcatheter approaches may offer an alternative for patients not amenable to surgery. METHODS: TriCLASP is a prospective, single-arm, multicenter European post-market clinical follow-up study (NCT04614402) to evaluate the safety and performance of the PASCAL system (Edwards Lifesciences) in patients with severe or greater TR. At 30 days, a composite of major adverse events (MAEs) adjudicated by a clinical events committee, echocardiographic parameters adjudicated by core laboratory, and clinical, functional, and quality-of-life measures were evaluated. RESULTS: Mean age of the 74 enrolled patients was 80.3 years, with 58.1% female, 90.5% systemic hypertension, and 77.0% in New York Heart Association (NYHA) class III/IV. Mean Society for Thoracic Surgeons score (MV repair) was 9.0%. TR severity was significantly reduced at discharge (p < 0.001) and sustained at 30 days (p < 0.001), and 90.0% of patients achieved ≤moderate TR. The composite MAE rate at 30 days was 3.0%, including 4 events in 2 patients: cardiovascular mortality 1.5%, stroke 1.5%, renal complications requiring unplanned dialysis or renal replacement therapy 1.5%, and severe bleeding 1.5%. There were no nonelective tricuspid valve reinterventions, major access site and vascular complications, major cardiac structural complications, or device embolizations. NYHA class I/II was achieved in 55.8%, 6-minute walk distance improved by 38.2 m (p < 0.001), and Kansas City cardiomyopathy questionnaire scores improved by 13.4 points (p < 0.001). CONCLUSION: Experience with the PASCAL transcatheter valve repair system in a European post-market setting confirms favorable safety and effectiveness at 30 days. TR significantly reduced, and clinical, functional, and quality-of-life outcomes significantly improved. This study is ongoing. Clinical Trial Registration: The study is ongoing and registered on ClinicalTrials.gov as NCT04614402. The current analysis is an interim report.

Right ventricular function in transcatheter mitral and tricuspid valve edge-to-edge repair.

Since transcatheter edge-to-edge repair (TEER) has become a valuable therapy in the treatment of both, mitral (MR) and tricuspid regurgitation (TR), the question of optimized patient selection has gained growing importance. After years of attributing rather little attention to the right ventricle (RV) and its function in the setting of valvular heart failure, this neglect has recently changed. The present review sought to summarize anatomy and function of the RV in a clinical context and aimed at presenting the current knowledge on how the RV influences outcomes after TEER for atrioventricular regurgitation. The anatomy of the RV is determined by its unique shape, which necessitates to use three-dimensional imaging methods for detailed and comprehensive characterization. Complex parameters such as RV to pulmonary artery coupling (RVPAc) have been developed to combine information of RV function and afterload which is primary determined by the pulmonary vasculature and LV filling pressure. Beyond that, TR, which is closely related to RV function also plays an important role in the setting of TEER. While mitral valve transcatheter edge-to-edge repair (M-TEER) leads to reduction of concomitant TR in some patients, the prognostic value of TR in the setting of M-TEER remains unclear. Overall, this review summarizes the current state of knowledge of the outstanding role of RV function and associated TR in the setting of TEER and outlines the unsolved questions associated with right-sided heart failure.