A randomised trial of carbon dioxide flushing to reduce vascular brain injury in patients undergoing TAVI

Stroke remains a significant concern in patients undergoing transcatheter aortic valve implantation (TAVI). Despite advances in TAVI technology and techniques, stroke rates have remained unchanged, with trials of cerebral embolic protection devices failing to reduce rates. The concept of air emboli has not been previously investigated in TAVI procedures. We hypothesised that gaseous emboli could play a significant role in TAVI and that carbon dioxide (CO₂) flushing of the TAVI valves could reduce the incidence of new neurological lesions post-TAVI.

We aimed to demonstrate the neuroprotective benefits of CO₂ flushing in TAVI patients.

INTERCEPTavi is a single-centre, blinded, randomised controlled pilot trial that studied the effects of flushing TAVI valves with CO₂ versus conventional saline on neurological outcomes post-TAVI, assessed using magnetic resonance imaging (MRI) and transcranial Doppler (TCD). Patients with aortic stenosis were randomised after obtaining vascular access. Periprocedural TCD assessed solid and gaseous emboli to the brain. Post-procedure, patients underwent brain MRI to detect lesions. Here, we report the primary outcome of feasibility, as well as the secondary MRI and mechanistic TCD outcomes.

A total of 60 patients were recruited and randomised 1:1 to CO₂ and saline flushing (TAVI-CO₂) versus saline flushing only (TAVI-S). CO₂ flushing significantly reduced the average number of lesions per patient (TAVI-CO₂: 4 lesions/patient vs TAVI-S: 8.5 lesions/patient; p=0.031). The total infarct area was numerically lower in the TAVI-CO₂ group (40.32 mm² vs 93.20 mm²), although this did not reach statistical significance (p=0.111). Similarly, TCD showed fewer microembolic signals in the TAVI-CO₂ arm, primarily due to a reduction in gaseous emboli, but this difference was not statistically significant (p=0.5).

INTERCEPTavi is a pioneering, first-in-human randomised trial that demonstrated that CO₂ flushing of the TAVI valve reduces the number of cerebral lesions measured on MRI. CO₂ flushing is an accessible, cost-effective method that can be easily implemented in any catheter laboratory to provide neurological advantages.