JACC: TEE feasible guide to TAVI, while sparing kidneys
Transesophageal echocardiography (TEE) may be a safe and effective primary imaging technique compared with angiography to guide transapical transcatheter aortic valve implantation (TA-TAVI), while reducing the potential risk of kidney failure, according to a study published in the February issue of the Journal of the American College of Cardiology: Cardiovascular Imaging.

TA-TAVI is performed on high-risk patients with severe symptomatic aortic stenosis in whom small and/or diseased iliofemoral arteries preclude the use of a transcatheter transfemoral approach. Angiography remains the primary imaging technique for guiding TAVI, however, several angiographic injections are often necessary to obtain the optimal view of the native aortic valve and to position the transcatheter valve, according to Rodrigo Bagur, MD, of the department of cardiology at Quebec Heart and Lung Institute, Laval University in Quebec City, Quebec, and co-authors.

TEE is commonly used as an adjunct to angiography in TA-TAVI. Despite a paucity of data regarding TEE’s use as a primary modality to guide TAVI, the ultrasound technique’s depiction of the aortic and ventricular ends of the transcatheter valve and ventricular referencing could facilitate valve positioning while lowering the amount of contrast media required to perform TAVI, Bagur and colleagues suggested.

The researchers sought to compare the effectiveness of TEE and fluoroscopy/angiography as primary imaging modalities for guiding TA-TAVI. One hundred patients diagnosed with symptomatic severe aortic stenosis underwent TA-TAVI, the first 25 under primary angiography guidance and the latter 75 with TEE as the main modality. Each modality was used to complement the primary technique in both groups.

The procedure was successful in 98 percent of patients, with 100 percent success in the angiography-TAVI group and 97.3 percent in the TEE-TAVI group. This difference was not statistically significant.

Average procedure time for the angiography group was 91 minutes, compared with 72 minutes using TEE. The mean contrast delivered to patients also differed significantly between the two groups, at 40 cm3 in the angiography group and 12 cm3 for TEE patients.

“It is well-known that the use of contrast media can complicate with the occurrence of AKI (contrast-induced nephropathy), especially in those patients with previous CKD [chronic kidney disease], and this complication has been associated with a significant increase in post-procedural mortality,” noted Bagur and colleagues. “Also, we have previously shown that the occurrence of AKI after TAVI was associated with a four-fold increase of in-hospital mortality after the procedure.”

The researchers reported a significant reduction in mean aortic gradient and an increase in aortic valve area following the procedure in both groups. In addition, 53 percent of patients had trivial and 13 percent mild aortic regurgitation after the procedure, with none of these differences reaching significance.

One-year survival rates were calculated at 84 percent for the angiography group and 75 percent for the TEE group.

The authors argued that the similar acute and midterm results for each group, and reduced contrast volume required for TEE, suggest “that performing TEE-TAVI procedures in a regular operating room with a standard fluoroscopic C-arm and without hybrid facilities is feasible and safe.”

Although Bagur and colleagues cited the importance of replicating their results in larger samples, an accompanying editorial supported a less dichotomous approach to utilizing either TEE or angiography as the primary TAVI guidance technique. “We consider both TEE and radiographic techniques to be essential,” wrote Lars G. Svensson, MD, PhD, and co-authors from the Cleveland Clinic Foundation.

In particular, Svensson and colleagues downplayed the importance of reduced costs and time in opting for TEE: “[A]lthough it is provocative to rely on only one imaging modality (TEE in this case, and many other reports suggesting radiography as the only imaging modality), it does not make practical sense to close ‘one eye’ to assess whether the cup is half full during the procedure in the environment where we are trying to perfect a new technique and potentially make it applicable for low-risk patients. It would be prudent to use all our imaging power to make the procedure as safe as possible for the current devices, particularly in centers that are commencing their use.”

Despite these arguments, Bagur and co-authors pointed to the relevance of their findings both to reducing kidney failure in the typically more predisposed elderly TAVI patients and to the potential of TEE to safely guide TAVI procedures in the growing number of facilities without hybrid operating rooms.