El embolismo cerebral es igual de frecuente en el implante de válvula aórtica transapical o transfemoral

Cerebral embolisms common but equal for transapical and transfemoral transcatheter valve procedures

Theheart.org
Por  Shelley Wood

Paris, France - A Canadian series comparing rates of MRI-documented cerebral embolism associated with transcatheter valve implantation (TAVI) in patients treated both transfemorally and transapically has shown that event rates are relatively high, with no different between groups.
The study is the latest to examine the problem of cerebral embolism in patients undergoing a procedure that is fast becoming the most-talked-about topic in interventional cardiology. Dr Josep Rodés-Cabau (Quebec Heart & Lung Institute, QC) presented the results of the study here at a EuroPCR 2010 hotline session Thursday.

As Rodés-Cabau explained, one of the proposed advantages of the transapical approach (considered the more "surgical" transcatheter procedure) over the purely percutaneous transfemoral procedure is that it avoids the manipulation of large catheters in the aortic arch and ascending aorta, plus the retrograde crossing of the aortic valve. In doing so, the transapical procedure theoretically might lead to a lower rate of cerebral embolism.
As reported by heartwire, a recent MRI analysis of transfemoral CoreValve (Medtronic) procedures found peri-interventional cerebral embolic lesions in 16 out of 22 patients, but a low incidence of persistent neurologic impairment.

TAVI and the brain
For the current study, Rodés-Cabau and colleagues performed cerebral diffusion-weighted MRI (DW-MRI) exams in patients participating in a prospective multicenter study of TAVI using the Sapien or Sapien XT valves (Edwards Lifesciences). A transapical or transfemoral procedure was selected on the basis of size, disease, and degree of calcification of the iliofemoral arteries. Twenty-nine patients were ultimately included in the transfemoral group and 31 in the transapical group. DW-MRI was performed within 24 hours of the TAVI procedure and again within the next six days, with all exams evaluated by a neuroradiologist. Neurological and cognitive function was subsequently assessed using standard exams.

In the first few hours postprocedure, DW-MRI identified new cerebral lesions in 68% of patients, 66% of transfemoral patients and 71% of transapical patients, a statistically nonsignificant difference. The total number of lesions was actually double in the transapical group (168 vs 83), with a mean number of lesions per patient being three for the transfemoral procedure and four for the transapical procedure. The vast majority of lesions were under 1 cm in size and no different between the two groups, with lesions distributed across the two cerebral hemispheres and vascular territories. No clinical, procedural, or imaging features were found to be predictors of new lesions, Rodés-Cabau added.

No evidence of impairment
Importantly, however, neurological and cognitive tests showed no evidence of impairment of any kind. Two clinically apparent strokes occurred—one in each group—within 24 hours of TAVI, leading to a clinical stroke rate in this study of 3.3%. 

"These results provide important insight into the mechanisms of cerebral embolism associated with TAVI and support the need for further research to both reduce the incidence of cerebral embolism during these procedures and to better determine their clinical relevance," he concluded.
During the Q&A session following his presentation, one audience member drew attention to the numeric differences in cerebral embolism numbers between the two groups. Rodés-Cabau, however, discounted the difference: "I really don't agree that the transapical group had more [embolisms]. I think the incidence was really equal in the two groups."

Asked whether he had any contextual information regarding the expected rates of cerebral embolism in patients undergoing conventional surgical aortic-valve replacement, Rodés-Cabau replied, "Unfortunately . . .  the surgical reports that we have reported [cerebral embolism rates of] about 50%, evaluated by MRI, but there are no studies that have been done in this octogenarian, very high-risk population," the kinds of surgery-ineligible patients currently receiving transcatheter valves.

Commenting on the study for heartwire, Dr Stephan Windecker (University Hospital, Bern, Switzerland), one of the session moderators, called the study "very interesting."
"The important message is that there is no difference between transapical and transfemoral. Particularly, some surgeons were outspoken that transapical would be associated with a lower risk of stroke or cerebral embolism, and that appears not to be the case from this study," he said. "The only thing you wonder about is the clinical relevance, because there was such a dichotomy between the clinical incidence of stroke—3.3%—and the absence of neurocognitive impairment, yet you have this high amount of lesions. You wonder, do they matter? I'm not an expert . . . but my question would be, are these reversible, and what do they mean?"