Aims: The implantation of percutaneous atrial septal occluder (ASO) devices for patent foramen ovale (PFO) may affect left atrial (LA) function. Some studies have reported short- to mid-term impairment of this function, though it remains unclear whether this is a transient or permanent negative effect, nor if all patients are equally susceptible to these changes. Methods and results: Observational, prospective study of consecutive patients with cryptogenic stroke (CS) undergoing percutaneous closure of PFO. Echocardiographic evaluation of evolving structural and functional parameters of the LA was carried out before procedure, inmediately after (within 24 hours), 6 and 18 months after device insertion. From March 2019 to October 2023, 170 patients with CS were enrolled, 82 eligible for PFO closure and 65 undergoing percutaneous closure. Baseline structural and functional parameters were within normal limits. At 6 months follow-up, there is a significant increase in LA volumes and a deterioration of reservoir and conduit functions measured by strain. There is a subsequent trend toward normalization, but baseline parameters are not reached by 18 months. Conclusions: PFO device closure negatively impacts on LA function, resulting in increased atrial volumes, worsening of left ventricular diastolic function, decreased reservoir and conduit function, and a compensatory increase in pump function. These changes are significant at 6 months, with partial improvement but without full normalization of parameters at 18 months follow-up.

The authors have declared no competing interest.

The study was approved by the Ethics Committee of Granada's Hospital Universitario Clínico San Cecilio (No. 0372-N-19), receiving approval on 5 th March 2019

The study is part of a standard practice protocol at our center and does not involve any modifications to the clinical activities of the participating healthcare professionals. The dedicated work of data extraction and analysis is part of doctoral studies. There is no external funding for any stage of this study.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The study was approved by the Ethics Committee of Granada's Hospital Universitario Clínico San Cecilio (No. 0372-N-19), receiving approval on 5 th March 2019

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

All data included in the study are available in a database specifically created for this research.