Continuous Remote Haemodynamic Monitoring With CardioMEMS™ Following Pulmonary Endarterectomy in Chronic Thromboembolic Pulmonary Hypertension:

Chronic thromboembolic pulmonary hypertension (CTEPH) is potentially curable by pulmonary endarterectomy (PEA), although a substantial proportion of patients develop residual pulmonary hypertension despite successful surgery. Currently, postoperative haemodynamic assessment relies on intermittent right heart catheterization, which does not provide information on the temporal evolution of pulmonary artery pressures during recovery.

The CTEPH-CardioMEMS study is a prospective, single-centre observational study evaluating the feasibility and clinical utility of continuous haemodynamic monitoring using the CardioMEMS™ system implanted intraoperatively during PEA. The primary objective is to characterize the postoperative trajectory of mean pulmonary artery pressure (mPAP), determine the time to haemodynamic stabilization, and explore the relationship between continuous pressure monitoring and clinical, echocardiographic, invasive haemodynamic and functional recovery.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a potentially curable form of pulmonary hypertension caused by persistent organized thromboembolic obstruction of the pulmonary arteries together with secondary pulmonary microvascular remodeling. Pulmonary endarterectomy (PEA) is the treatment of choice for operable disease and results in normalization of pulmonary haemodynamics in many patients. However, a substantial proportion of patients develop persistent or residual pulmonary hypertension after surgery, which is associated with persistent symptoms, right ventricular dysfunction, need for additional balloon pulmonary angioplasty or pulmonary hypertension-targeted therapy, and worse long-term outcomes.

Current postoperative follow-up combines clinical evaluation, laboratory biomarkers, transthoracic echocardiography, pulmonary function tests, cardiopulmonary exercise testing (CPET), and right heart catheterization (RHC). Although RHC remains the reference standard for haemodynamic assessment, it provides only isolated measurements and cannot characterize the dynamic haemodynamic changes occurring during the early postoperative period. Consequently, the temporal pattern of pulmonary artery pressure recovery following PEA remains largely unknown.

The CardioMEMS™ HF System is a wireless implantable pulmonary artery pressure sensor that enables continuous remote monitoring of pulmonary artery pressures through daily measurements. Although its safety and clinical benefit have been demonstrated in patients with heart failure, experience in patients with CTEPH is currently lacking. In this study, the device will be implanted intraoperatively under direct surgical visualization during PEA, avoiding the need for an additional percutaneous implantation procedure.**

The CTEPH-CardioMEMS study is a prospective, single-centre, exploratory observational study designed to characterize the postoperative trajectory of mean pulmonary artery pressure after PEA. The primary endpoint is the time from surgery to haemodynamic stabilization, defined according to a pre-specified longitudinal criterion based on daily CardioMEMS™ measurements. Secondary objectives include evaluating the relationship between continuous haemodynamic data and clinical status, laboratory findings, right ventricular remodeling assessed by echocardiography, invasive haemodynamics obtained by RHC, functional capacity assessed by CPET, quality of life, need for pulmonary hypertension-specific therapy, balloon pulmonary angioplasty, and clinical outcomes. Given its pilot nature, the study incorporates a risk-enrichment strategy aimed at preferentially including patients considered to be at increased risk of residual pulmonary hypertension, while maintaining consecutive screening of all patients discussed by the multidisciplinary CTEPH team. The study is intended to provide the first comprehensive description of continuous haemodynamic recovery after PEA, assess the feasibility and safety of CardioMEMS™ monitoring in this population, and generate data to support future multicentre confirmatory studies

• CardioMEMS (Device): CardioMEMS™ implantation: The sensor will be implanted intraoperatively during pulmonary endarterectomy, under direct vision, into a subsegmental pulmonary artery branch with a minimum diameter of 7 mm. Implantation in this manner requires no additional percutaneous procedure and does not add to surgical risk; direct-vision placement allows accurate positioning within a thrombus-free segment. The device is intended to remain permanently in situ. All patients with CTEPH continue lifelong anticoagulation; although published device-related thrombosis/embolism rates are low (under 1 per 1000 implants), these data derive from cohorts without mandatory lifelong anticoagulation, and safety in this specific population is therefore a pre-specified objective of the study.7

Primary outcomes

• Time to stabilization mPAP [From PEA to 12 months]: The primary endpoint of the study will be the time from pulmonary endarterectomy (PEA) to stabilization of mean pulmonary artery pressure (mPAP), as assessed by continuous remote monitoring with the CardioMEMS™ system. Hemodynamic stabilization will be operationally defined as the first postoperative day on which the 7-day moving average of mPAP remains stable (variation <10%) for three consecutive days, in the absence of any intercurrent clinical event or therapeutic intervention that could account for changes in pulmonary artery pressure.

Sex: All, ages: 18 Years to 80 Years

Given the exploratory proof-of-concept nature of the study and the limited sample, a risk enrichment strategy will be applied. Whenever possible, patient selection will preferentially include individuals considered to be at increased risk of residual pulmonary hypertension after PEA. High-risk features include severe preoperative haemodynamic impairment (pulmonary vascular resistance ≥8 Wood units/645dyn.s.cm-5), predominantly distal thromboembolic disease on preoperative imaging, delayed referral for PEA (>2 years from diagnosis), or clinical characteristics associated with pulmonary microvascular disease (including antiphospholipid syndrome, splenectomy, chronic inflammatory or haematological disorders, or previous malignancy). These features are intended to enrich the study population with patients more likely to develop clinically relevant haemodynamic trajectories and should not be interpreted as validated predictors of residual pulmonary hypertension.

In addition, the multidisciplinary CTEPH team may recommend inclusion of patients who do not strictly fulfil the above enrichment features but are considered, based on an integrated assessment of clinical characteristics, imaging findings, haemodynamic profile and surgical considerations, to be at increased risk of residual pulmonary hypertension or likely to derive particular benefit from continuous haemodynamic monitoring. This decision will be made by consensus and documented prospectively before study inclusion.

Inclusion criteria 1. Age ≥18 years. 2. Confirmed diagnosis of CTEPH according to current international guidelines. 3. Multidisciplinary indication for pulmonary endarterectomy. 4. Considered suitable for intraoperative CardioMEMS™ implantation. 5. Ability to comply with remote monitoring and scheduled follow-up. 6. Written informed consent. Exclusion criteria

1. Age <18 years.
2. Inability or unwillingness to provide written informed consent.
3. Contraindication to CardioMEMS™ implantation according to the manufacturer's instructions for use or investigator judgement.
4. Life expectancy <1 year due to a non-cardiopulmonary comorbidity.
5. Inability to perform remote transmissions or comply with scheduled follow-up.
6. Any condition that, in the opinion of the investigators, may compromise patient safety, study participation or data quality.

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