Objective Histological analyses of debris captured by a cerebral protection system (CPS) during transcatheter valve-in-valve (VIV) procedures have not been reported.

Methods Fifteen consecutive patients with stenotic aortic (n=13) or mitral (n=2) surgical or transcatheter bioprostheses were treated with implantation of a transcatheter heart valve (THV) in the presence of a dual-filter CPS. Mean patient age was 75 years; mean logistic EuroSCORE was 31%. Filters were collected and histological assessment of debris was performed. Patients were followed clinically until discharge.

Results Debris captured by either or both filters was detected in all patients. Acute thrombus was the most common type of debris, found in all patients, followed in frequency by arterial wall tissue (n=12 patients (80%)), calcification (n=11 (73%)) and valve tissue (n=9 (60%)). Less frequently found were organised thrombus (n=5 (30%)), foreign material (n=4 (27%)) and myocardium (n=2 (13%)). A median of 123 debris particles per patient was detected, with a trend towards a greater median number of particles collected in proximal filters (78 vs 39, p=0.065). The average maximum particle diameter was 88 (range 56–175) µm, with a median of 20 particles ≥150 µm. No stroke or transient ischaemic attack (TIA) had occurred by the time of discharge (mean 8 days).

Conclusions Transcatheter VIV procedures were associated with the release of particulate debris into the cerebral circulation in all patients. The type of debris suggests that debris originates predominantly from arterial and valvular passage of the THV.