Cerebral Embolization During Transcatheter Aortic Valve Implantation: A Transcranial Doppler Study

BACKGROUND: Transcatheter aortic valve implantation (TAVI) is associated with a higher risk of neurological events for both the transfemoral (TF) and the transapical (TA) approach than surgical valve replacement. Cerebral magnetic resonance imaging revealed even more new, albeit clinically silent lesions from procedural embolization. Yet, main source and predominant procedural step of emboli remain unclear.

METHODS AND RESULTS: Eighty-three patients underwent TF- (Medtronic CoreValve [MCV]: n=32, Edwards Sapien [ES]: n=26) and TA-TAVI (ES: n=25). Serial transcranial Doppler (TCD) examinations prior, during and three months after TAVI were used to identify high-intensity transient signals (HITS) as a surrogate for microembolization. Procedural HITS were detected in all patients, predominantly during manipulation of the calcified aortic valve while positioning and implanting the stent-valves. The balloon-expandable ES prosthesis caused significantly more HITS during positioning (ES(TF): 259.9 [184.8-334.9], ES(TA): 206.1[162.5-249.7], MCV(TF): 78.5 [25.3-131.6], p<0.001), the self-expandable MCV prosthesis during implantation (MCV(TF): 397.1 [302.1-492.2], ES(TF): 88.2 [70.2-106.3], ES(TA): 110.7 [82.0-139.3], p<0.001). Overall, there were no significant differences between TF- and TA-TAVI and between the MCV and the ES prosthesis. No HITS were detected at baseline and at 3-months follow-up. There was one major procedural stroke resulting in death and one minor procedural stroke with full recovery at 3-months follow-up in the MCV group.

CONCLUSIONS: Procedural HITS were detected by TCD in all patients. While no difference was observed between the transfemoral and the transapical approach using the balloon-expandable ES stent-valve, TF-TAVI with the self-expandable MCV prosthesis resulted in the highest amount of HITS, predominantly during implantation.