The Relationship Between Patent Foramen Ovale and Unexplained Dizziness: A Prospective Analysis in China

Qian Cao,1,&ast; Yu Shen,1,2,&ast; Zhuo Hou,1 Defu Li,3 Boji Tang,1 Lijun Xu,1 Yanping Li4 1Department of Neurology, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People’s Republic of China; 2Department of Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, People’s Republic of China; 3Jiangxi Provincial Key Laboratory of Preventive Medicine, Nanchang University School of Public Health, Nanchang, Jiangxi, People’s Republic of China; 4Department of Neuroelectrophysiology, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Lijun Xu, Department of Neurology, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People’s Republic of China, Email xulijun20050901@sina.com Yanping Li, Department of Neuroelectrophysiology, The Second Affiliated Hospital of Nanchang University, No. 1, Minde Road, Nanchang, Jiangxi, People’s Republic of China, Email 359173628@qq.comIntroduction: Patent foramen ovale (PFO) is potentially associated with abnormal embolisms, and it results in mixing of arteriovenous blood when its right-to-left shunt (RLS) emerges. Present studies have found that PFO is a risk factor that can lead to many diseases. However, few studies have examined the relationship between PFO and dizziness.Methods: This study was a large single-center, prospective, controlled study. From March 2019 to March 2021, we recruited patients with dizziness were divided into two groups: “explained” and “unexplained”. All patients were submitted to contrast-enhanced transcranial Doppler ultrasound and screened for PFO. Transesophageal heart ultrasound or right heart catheterization was used to confirm PFO. Additionally, multiple factors were collected and statistical analysis was performed between the two groups.Results: Among the 244 patients included, 123 were in the “explained” group and 121 were in the “unexplained” group. The prevalence of PFO in the “explained” group was 34 (27.4%) compared to 79 (64.7%) in the “unexplained” group. In the “explained” group, 7 were RLS level IV, 6 were level III, 7 were level II, and 14 were level I. For the “unexplained” group, the numbers of patients with levels IV, III, II and I were 27, 26, 12 and 14, respectively. Univariate analysis revealed that PFO (χ2= 34.77, P < 0.001) and age (t = − 3.49, P < 0.001) seemed to be potential risk factor candidates for “unexplained” dizziness. In multiple regression analysis, age (OR = 0.97; 95% CI 0.95– 0.99) and the prevalence of PFO (OR = 4.37; 95% CI 2.50– 7.63) were statistically significant. Massively shunted PFO showed more pronounced risk factors (OR = 8.76; 95% CI 4.04– 19.03).Conclusion: There was a high prevalence of PFO and a greater RLS level in unexplained dizziness. PFO and age were independent risk factors for unexplained dizziness. When treating with unexplained dizziness, especially among young people, we must pay attention to the presence of PFO.Keywords: patent foramen ovale, PFO, right to left shunt, RLS, unexplained dizziness, contrast-enhanced transcranial Doppler ultrasound, cTCD