Interatrial Shunting with the Atrial Flow Regulator: Balancing Left- and Right-Sided Hemodynamics

ABSTRACT

Background: Pulmonary hypertension (PH) and heart failure with preserved or reduced ejection fraction (HFpEF/HFrEF) are characterized by elevated filling pressures, limited therapeutic options, and high morbidity. The Occlutech Atrial Flow Regulator (AFR) is a percutaneously implanted, double-disc nitinol device that creates a controlled interatrial shunt. By facilitating left-to-right or right-to-left flow depending on the hemodynamic substrate, the AFR offers a mechanistically attractive approach to decompress atrial chambers and improve symptoms.

Methods: A systematic review was performed in accordance with PRISMA guidelines. Literature from PubMed, Scopus, and Google Scholar (2000–2024) were screened to identify clinical studies, registries, and case reports evaluating AFR implantation in patients with HF or PH. Data were synthesized regarding device design, procedural success, clinical efficacy, safety, and long-term outcomes, with emphasis on adverse events and hemodynamic thresholds.

Results: Across prospective studies in Group 2 PH/HF populations, AFR implantation demon­strated high procedural success, durable patency, and improvements in NYHA class, six-minute walk distance, pulmonary capillary wedge pressure, and quality of life. Safety outcomes were favorable, although right ventricular dilation and adverse remodeling were observed with larger shunt sizes or in patients with elevated pulmonary vascular resistance. In Group 1 PAH, compassionate-use series reported reductions in right atrial pressure, improvements in cardiac index and functional class, and resolution of syncope, though at the expense of systemic desaturation. Mortality in these cohorts was primarily determined by baseline disease severity rather than device complications. Evidence from comparator devices (IASD, V-Wave) and the REDUCE LAP-HF II trial underscores the critical importance of patient selection, with benefit concentrated in patients demonstrating preserved pulmonary vascular reserve.

Conclusions: The AFR represents a promising device-based therapy for patients with advanced HF or PAH by providing controlled interatrial shunting tailored to the underlying physiology. Current data establish its feasibility, safety, and symptomatic benefit in well-selected patients, but highlight risks of worsening PH and right-sided loading if applied outside defined hemodynamic thresholds. Ongoing pivotal trials, including FROST-HF and RESPONDER-HF, are essential to determine the role of AFR in routine clinical practice and to refine phenotypically guided patient selection.

Keywords: Intra-atrial shunt, pulmonary hypertension, LV failure