PARIS, France—Transcatheter aortic valve implantation (TAVI) is associated with a high rate of new silent cerebral ischemic lesions, regardless of whether the procedure is performed via transfemoral or transapical access, according to late-breaking data presented May 27 at EuroPCR 2010. However, these lesions did not result in neurological or cognitive impairment.

Transfemoral TAVI has been linked previously to newly developed cerebral embolism on diffusion-weighted magnetic resonance imaging (MRI), reported study investigator Josep Rodés-Cabau, MD, of Laval University (Quebec City, Canada). “The transapical TAVI approach avoids both the manipulation of large catheters in the aortic arch/ascending aorta and the retrograde crossing of the aortic valve, and this might lead to a lower rate of cerebral embolism,” he proposed, adding that the incidence of cerebral embolism on MRI following transapical TAVI is unknown.

Dr. Rodés-Cabau and colleagues prospectively evaluated patients, including those with severe symptomatic aortic stenosis, who underwent TAVI under the Canadian compassionate use program. Subjects were selected for the transfemoral or transapical approach based on the size, disease, and degree of calcification of the iliofemoral arteries. Procedures were performed using the 23- or 26-mm Edwards Sapien or Edwards Sapien XT valves (Edwards Lifesciences, Irvine, CA).

MRI was conducted within 24 hours before and within 6 days after TAVI.

Among 81 patients who underwent TAVI and had preprocedural MRI, 37 were selected for transfemoral access and 44 for transapical access. After several subjects withdrew for various reasons including death and pacemaker implantation, the final analysis included 29 transfemoral patients and 31 transapical patients.

Cerebral Lesions Common

After TAVI, a total of 68% of patients exhibited signs of new lesions on MRI, with each group showing similar rates (66% with transfemoral vs. 71% with transapical; P = 0.78). This difference remained nonsignificant after adjustment for baseline clinical characteristics. A total of 83 new lesions were found in transfemoral patients and 168 in transapical patients, with a median number of 3 lesions per patient. Most patients had multiple lesions, which tended to be equally distributed across the left and right cerebral hemispheres and in both the anterior and posterior circulation territories. Approximately 91% of lesions measured less than 1 cm. None were larger than 5 cm in diameter.

Baseline clinical, echocardiographic, CT, and procedural characteristics were similar between patients with and without new cerebral lesions. Multivariate analysis was performed on all variables with P values less than 0.2 in univariate analysis; none proved to be significant predictors of lesion development.

There was no deterioration in neurological or cognitive status after TAVI, although 2 patients (1 in each group) experienced a clinically apparent stroke within 24 hours.

“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 better determine their clinical relevance,” Dr. Rodés-Cabau concluded.

Data Spark Discussion

Following Dr. Rodés-Cabau's presentation, an attendee expressed curiosity about an apparent contradiction: the transapical approach showed a nonsignficant trend toward a higher rate of new lesions even though the transfemoral group had a higher degree of valve calcification.

“In fact, the way that we measure the amount of calcium in the valve, by computed tomography, doesn't take into account whether or not the calcium is integrated in the valve or is on the surface of the valve. The surgeons know very well that these are very different scenarios and probably the potential for embolism will [vary as well],” Dr. Rodés-Cabau explained, adding that these measurements were only available for two-thirds of the study cohort. Another explanation for the higher calcification in the transfemoral group might be the fact that these patients had a significantly larger aortic annulus diameter (mean 23 ± 2 mm vs. 21 ± 2 mm; P < 0.0001).

However, “I do not agree that the transapical approach tended to have more [lesions]. The incidence of cerebral embolism was really equal in the 2 groups,” he stressed.

Asked by session co-chair Stephan Windecker, MD, of Bern University Hospital (Bern, Switzerland), to describe the study's antithrombotic and antiplatelet regimen, Dr. Rodés-Cabau replied that almost all patients were pretreated with aspirin. Few transapical patients received clopidogrel pretreatment, compared with half in the transfemoral group. “However, we analyzed whether or not this could influence the rate of cerebral embolism, and we didn't find any relationship,” he said. All patients also received heparin during the procedure.

“It's incredibly important that you're looking at this really breakthrough technology to figure out what might be modifiable risk factors so that we can optimize the treatment,” commented co-chair Laura Mauri, MD, MSc, of Brigham and Women's Hospital (Boston, MA), who asked how the findings for cerebral embolism stood up against surgical results.

Unfortunately, said Dr. Rodés-Cabau, the surgical literature tends to focus on lower risk and younger patients, so it is difficult to draw comparisons. That being said, the rate of cerebral embolism observed on MRI in that population is approximately 50%, he reported.

Study Details

All MRI exams were examined by a neuroradiologist blinded to the clinical data. At both MRI time points, neurological function was evaluated according to the National Institutes of Health Stroke Scale and cognitive function with the Mini-Mental State Examination. Mean patient age was 83 years, and 10% had significant carotid stenosis at baseline. Transapical patients were significantly more likely to have dyslipidemia, CAD, or peripheral vascular disease.

Disclosures:

• Dr. Rodés-Cabau reports consulting for Edwards Lifesciences.

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