Quantification of Patent Foramen Ovale Shunt Severity by TEE and TCD in Routine Clinical Practice

Background The presence of a large physiologic shunt, defined as >20 left atrial microbubbles within 3 cardiac cycles on transesophageal echocardiography (TEE) is a randomized controlled trial- validated indication for patent foramen ovale (PFO) closure in patients with otherwise cryptogenic ischemic stroke. The frequency with which this information is available to treating physicians from clinical TEE reports has not been well delineated. Methods Among consecutive ischemic stroke patients admitted to an academic medical center undergoing TEE between October 2022 - September 2023, TEE reports were reviewed to determine frequency with which formal clinical-trial definition-adherent characterization of PFO shunt size was provided, the frequency of informal PFO shunt size descriptions, and correlations with transcranial Doppler (TCD) formal shunt grades (Spencer Grades 1-5). Results Among 77 patients, the median age was 64 (IQR 56-73), and 33 (43%) were female. On TEE, shunt presence was assessed by bubble study in 60 (78%), direct Doppler alone in 5 (7%), and neither in 12 (16%). Among patients with bubble study, a right-to-left shunt (RLS) potentially due to PFO was present 25 (42%). RLS severity was quantified on the clinical report in 16% (4/25) of PFO patients, all with small (<20) shunts. For the remaining 21 (84%), reports informally characterized shunt severity with various descriptive terms, including “small/mild/trace” (13 cases), “moderate/medium” (6), and “large” (1). TCD bubble studies were performed in 76% (19/25) of the TEE RLS PFO patients. Shunt severity correlation between TEE and TCD was 100% (3/3) for the formally quantified TEE shunts, un- assessable in one patient with non-specific shunt size characterization on TEE, and poor (3/15, 20%) for the remaining 15 informally assessed TEE shunts, with 47% (7/15) of shunts categorized as larger on TCD and 33% (5/15) smaller on TCD than TEE. Conclusions Quantified, evidence-based ratings of PFO shunt severity were present in less than 1 of every 6 TEE reports, and unquantified, informal size estimates correlated poorly with TCD quantification of shunt severity. Patient management would be aided by inclusion of formal PFO shunt size quantification in all clinical stroke patient TEE reports.