Background: Elevated left atrial pressure is often a consequence of left ventricular diastolic dysfunction. Patent foramen ovale (PFO) with left-to-right shunt could serve as a left atrium unloading factor. The aim of the study was to test whether PFO in patients with atrial fibrillation (AF) is linked to lower left atrial pressure (LAP). Methods: A retrospective analysis was performed on consecutive patients undergoing AF ablation from 2019 to 2023. The presence of PFO was assessed with standard transesophageal echocardiography, performed in all patients before ablation. LAP was measured directly in the left atrium just after transseptal puncture. Mean LAP was analyzed. Results: A total of 409 patients were included in the analysis, 85 of whom had PFO (20.8%). There were no significant differences between the groups in baseline characteristics such as age, sex, and comorbidities. Overall, 34.4% of patients had a history of heart failure, independent of the presence of a patent foramen ovale (PFO). Mean LAP was not significantly different between patients with and without PFO (p = 0.36). Conclusions: In patients undergoing AF ablation, more than 20% of patients have PFO. The presence of PFO does not significantly influence LAP, measured directly in the left atrium. The presence of PFO is not linked to a lower prevalence of heart failure.