Pickering Syndrome prevalence in patients presenting with recurrent acute pulmonary edema to the Emergencies Department of three European Hospitals

The Pickering Syndrome, first described in 1988 as the association between recurrent episodes of rapidly developing pulmonary edema and arterial hypertension secondary to bilateral significant renal arteries stenosis (RAS) - or unilateral stenosis in patients with a single kidney- is an underdiagnosed and undertreated pathology. Its prevalence has never been estimated and, despite the evidence that shows the benefit that renal revascularization provides to these patients, diagnostic evaluations have decreased during the last years. A recent case series showed that significant RAS can be effectively assessed by non-invasive, non-nephrotoxic methods, such as the renal doppler ultrasound (RUS) and abdominal computed tomography (CT) scan without intravascular contrast. This study aims to estimate the prevalence of Pickering Syndrome in patients presenting with recurrent acute pulmonary edema to the Emergency Department (ED). We believe this effort will increase general awareness of the syndrome, thereby improving its diagnosis and treatment. This is an observational, descriptive, retrospective and multicentric study, involving two European tertiary-level hospitals – the Hospital Universitario Central de Asturias (H.U.C.A) in Oviedo, Spain, and the Azienda Ospedaliera Università di Padova (A.O.P.D) in Padova, Italy- and a secondary-level national hospital, the Ospedale Ca’ Foncello in Treviso, Italy. We included 650 adult patients who presented in the ED with a triage code of ‘’respiratory distress’’, ‘’dyspnea’’ or ‘’poor general conditions’’ and were admitted with a diagnosis of ‘’pulmonary edema’’, excluding cases involving concomitant pathologies such as acute coronary syndromes or non-cardiogenic pulmonary edema. We analyzed demographic and clinical variables, laboratory findings, presence of risk factors (story of high blood pressure [HBP], chronic kidney disfunction [CKD], recurrent heart failure) as well as the work-up performed (abdominal CT scan, RUS, renal arteriography) and renal revascularization procedures. Patients with a high pre-test probability of Pickering Syndrome—based on a history of hypertension, CKD, recurrent heart failure, and rapidly developing pulmonary edema (symptom onset within <24 hours)—comprised 4% of the cohort. Of the 245 patients who underwent abdominal CT scans, only 90 had reports describing renal arteries. Stenosis was often vaguely described as "significant" or not, without specifying severity. Among these, we identified four patients with significant bilateral stenosis (>70%), two of whom met the clinical criteria for Pickering Syndrome. Based on these results, we estimated a confirmed prevalence of Pickering Syndrome of 0.3%. Only 21 patients underwent RUS, most of which were inconclusive. No cases of significant bilateral or unilateral RAS (in single-functioning kidney patients) were identified from these studies. Four patients underwent renal arteriography, and two underwent renal revascularization. The retrospective design inherently limited data completeness and accuracy. Variability in triage coding and diagnostic practices across centers likely resulted in selection bias, with potentially eligible cases being excluded during data extraction. Furthermore, the reliance on historical imaging studies underestimates the true burden of renal artery stenosis, as disease progression may have occurred over time; the lack of standardized reporting of stenosis severity further 4 reduced the study's diagnostic yield. Future studies should address these limitations through prospective designs with uniform diagnostic criteria. In conclusion, this study highlights the rarity but critical clinical significance of Pickering Syndrome in patients presenting with recurrent flash pulmonary edema.