Background: Embolic stroke of undetermined source (ESUS) comprises a large ischaemic stroke diagnostic subgroup, especially in patients aged under 65 years. Embolic stroke workup involves screening blood tests, cardiac monitoring and often a bubble-enhanced Transthoracic Echocardiogram (TTE) to exclude a patent foramen ovale (PFO). A PFO is present in 25% of the general population, but present in up to 50% of young ESUS patients, and causal in many. Transcranial Doppler for detection of PFO has been studied previously but has not been widely protocolised in Australia in ESUS diagnostic workup.
Aims: We investigated in an Australian context, the role of TCD versus bubble-enhanced TTE in ESUS patients aged under 65 years. Our aim was to compare the sensitivity and specificity of both tests against gold-standard transoesophageal echocardiogram (TOE) and review our algorithm for ESUS investigation.
Methods: 54 ESUS patients were screened with both TCD and bubble-enhanced TTE from September 2022 – March 2023 (median age 55 (interquartile range 19). All cases without an alternate clear cause also underwent TOE (n=52).
Results: 25 of 52 patients had evidence of a PFO on TOE. TCD had a higher sensitivity (100% [95% confidence interval (CI): 87-100]) than TTE (88% [95%CI: 69-98]), and higher negative predictive value (100% [95%CI: 88-100]) vs (90% [95%CI: 74-98]) for PFO-detection in ESUS. Three cases were TTE negative/TCD positive. All were subsequently confirmed with gold-standard TOE.
Conclusion: Despite relatively small numbers, TCD appears more accurate than bubble-enhanced TTE in ESUS under 65 for detection of PFO at our tertiary stroke centre. As a result, we have revised our ESUS diagnostic algorithm; TCD is used as first line for shunt detection, and TTE without bubble used to investigate structural cardioembolic causes.