Cerebral Embolization Greater When Valvuloplasty Not Done Before TAVR

Skipping balloon aortic valvuloplasty (BAV) before balloon-expandable TAVR shortens procedure time and lessens contrast amount but may increase the volume of cerebral ischemic lesions detected days after the procedure, according to an observational study published online September 16, 2015, ahead of print in JACC: Cardiovascular Interventions.

Joachim Schofer, MD, PhD, of Albertinen Heart Center (Hamburg, Germany), and colleagues looked at data on 87 consecutive high-risk patients older than 75 years who underwent TAVR at a single center and had no contraindications to diffusion-weighted MRI (DW-MRI) at 2 to 7 days after the procedure.

Overall, 32 patients underwent BAV before TAVR. Valvuloplasty was used routinely in those who received a Sapien XT valve (n = 19) and in the subset of patients implanted with the Sapien 3 valve (n = 13; both Edwards Lifesciences) who had severe asymmetric valve calcification or a planimetric aortic valve orifice area ≤ 0.5 as measured by intraprocedural TEE. It was skipped in the remaining 55 patients, who all received Sapien 3 valves.

Baseline characteristics and echocardiographic parameters were similar regardless of whether BAV was performed before TAVR.

Procedural success was slightly lower in the BAV group (93.5% vs 98.2%). Procedures were shorter (58.7 vs 69.2 minutes; P = .0008) and contrast volume was lower (69.8 vs 97.0 mL; P = .0004) when BAV was skipped. The rate of paravalvular leak did not differ between groups. Postdilation was performed in 1 patient in the BAV group and 3 in the no-BAV group due to moderate aortic regurgitation.

In the 3 days after TAVR, 4 patients (3 without BAV and 1 with BAV) had a clinically apparent stroke and were excluded from further study.

Ischemic Lesion Volume Higher Without BAV

DW-MRI performed an average of 4.8 days after TAVR—4.3 and 5.1 days in the BAV and no-BAV groups, respectively—identified new cerebral ischemic lesions in 66.7% of patients. Total lesion volume was greater in patients who did not undergo BAV (235.4 vs 89.5 mm³; P = .01); incidence and number of ischemic lesions were numerically higher in the no-BAV group, but the differences were not significant.

Lesions were bilateral in 43.1% of affected patients, in the right hemisphere in 24.1%, and in the left hemisphere in 32.8%.

At 30 days, MACCE (death, MI, or stroke) did not occur in any patients. Major vascular complications defined by Valve Academic Research Consortium (VARC)-2 criteria occurred in 3 patients; all had major access site-related bleeding requiring surgical intervention. In addition, 10.3% of patients required a covered stent to treat access site-related perforation or dissection. Vascular complications did not differ based on BAV use.

Difference in Lesion Volume Unexplained

It has been believed that BAV is necessary before balloon-expandable TAVR “to facilitate the crossing of the calcified aortic valve,” Dr. Schofer and colleagues write. “BAV, however, may be associated with several adverse events. It needs rapid pacing, which in the presence of poor left ventricular function may increase the risk of the procedure; it may be associated with aortic rupture; and it may be in part responsible for cerebral embolization with the risk of stroke.”

Use of the newer-generation, lower profile Sapien 3 in the study and in general “may facilitate a direct valve implantation” without the need for BAV, the authors write, adding that it was assumed that avoiding BAV with the newer valve would reduce the risk of cerebral embolization.

The finding that this was not the case, however, is “very surprising and unexpected,” Isaac George, MD, of Columbia University Medical Center (New York, NY), told TCTMD in an email.

“There is no obvious explanation [for this] result,” he said. “The authors suggest that BAV may result in smaller pieces of calcium that are dislodged. It is hard to believe this explanation from a physiologic or mechanical standpoint. A more logical explanation may be that, despite weak matching for baseline characteristics, the patients who underwent BAV actually had lower burdens of calcium on the valve or less severe overall disease or lower thrombotic risk.”

Clinical Impact Unclear

It remains to be seen whether the increase in cerebral embolization without BAV translates into a higher stroke risk, the study authors say. “Even if not, cerebral ischemic lesions potentially deteriorate neurocognitive function and should therefore be avoided. Cerebral embolic protection devices may be of specific value for [TAVR] without BAV using a balloon-expandable valve.”

They note that prior research has shown that cerebral ischemic lesions are found by DW-MRI in upwards of 74% of patients after TAVR and that patients with ischemic lesions have a 3-fold greater risk of stroke. Although lesions are typically not associated with neurological symptoms, there is evidence supporting a link between lesions and dementia and cognitive decline.

Preliminary studies have suggested that cerebral protection devices might be beneficial. In CLEAN-TAVI, using such a device reduced the number of DW-MRI lesions. That, in turn, was associated with improvement in short-term neurological outcome. DEFLECT III yielded similar results.

Dr. George said the current study highlights the possibility that protection devices will be beneficial. “They are low risk and may offer protection from large-volume emboli, regardless of whether [balloon-expandable] or self-expanding TAVR [is used],” he noted. “As always, careful and meticulous technique during TAVR may mitigate some of this embolic risk.”

Dr. Schofer and colleagues acknowledge that their study was limited by its nonrandomized design and the use of a small number of patients from a single center. Thus, they say, the findings need to be confirmed in a randomized trial.

Dr. George agreed that current paper does not provide the final answer. “These data are purely observational and can only be treated as such,” he said. “The study raises a question that has been asked before, and may help guide discourse for future studies. However, by no means can it guide clinical practice.”

“At some point, the question of pre-BAV vs no BAV vs postdilatation BAV will need to be addressed systematically in a well-designed trial,” he concluded.

Source: 
Bijuklic K, Haselbach T, Witt J, et al. Increased risk of cerebral embolization after implantation of a balloon expandable aortic valve without prior balloon valvuloplasty. J Am Coll Cardiol Intv. 2015;Epub ahead of print.

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