A process of flushing prosthetic valves using carbon dioxide (CO2) prior to transcatheter aortic valve implantation (TAVI) may provide a neuroprotective benefit by halving cerebral infarcts caused by air embolisation during the procedure.
The technique is affordable, easy to use, and does not add time to the procedure, and could potentially be employed in every cath lab to improve the safety of TAVI, investigators claim.
These were among the conclusions of INTERCEPTavi, a first-in-man study whose findings were presented during a late-breaking trial session at EuroPCR 2023 (16–19 May, Paris, France) by Saud Khawaja (Hammersmith Hospital, London, UK).
Stroke remains a significant concern in TAVI, Khawaja told the EuroPCR audience, adding that there is increasing recognition that patients may suffer “covert” neurovascular injury that is not clinically identifiable, which may be associated with future stroke, dementia and depression.
Prosthetic TAVI valves and stent grafts for thoracic endovascular aneurysm repair (TEVAR) retain air during the manufacturing process, Khawaja commented, pointing to in vitro testing of valves that have demonstrated the release of air bubbles during deployment. Additionally, he noted that studies using transcranial Doppler during TEVAR to detect microembolic signals during the procedure have shown more than 90% of these to be gaseous in nature.
A pilot study looking at CO2 flushing of TEVAR stent grafts prior to their implant showed no gaseous microembolic signals on transcranial Doppler, as well as a reduction in vascular brain infarcts measured on diffusion-weighted magnetic resonance imaging (DW-MRI, Khawaja said.
INTERCEPTavi sought to investigate the importance of air emboli in TAVI, as well as the potential neuroprotective benefits of minimising their occurrence during the TAVI procedure by using the CO2 flushing technique. Investigators recruited 60 patients undergoing transfemoral TAVI for severe aortic stenosis at Imperial College Healthcare NHS Trust between August 2021 and February 2023.
Patients were randomised 1:1 to the intervention arm, where valves were flushed using CO2 and saline, and the control arm, where valves were prepared with saline only. Patients underwent neurocognitive assessment, neurological examination and serum biomarkers prior to the procedure, and underwent a DW-MRI in the first seven days after their procedure. Neurocognitive assessment was also then carried out at six weeks and six months after their procedure.
Khawaja reported that the total number of lesions was significantly higher among patients treated in the control group, with 75 lesions in 18 patients reported in the CO2 flushing group and 144 in the saline group (4.2 and 9 lesions per patient in the respective cohorts). This represents “a significant reduction of nearly half by flushing” according to Khawaja.
“INTERCEPTavi is the first study that highlights the importance of air emboli in TAVI and potential associated brain injury,” Khawaja told EuroPCR attendees. “The study demonstrates that there is a neuroprotective benefit of flushing the TAVI valves using CO2, and we can half the number of cerebral infarcts on brain MRI”, he said.
Khawaja stressed the importance of a multicentre randomised controlled trial using solid embolic protection devices and CO2 flushing to see if they are complementary as a next step.