Smaller Delivery System Means Fewer Complications with Aortic Valve Implantation

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The latest iteration of a leading percutaneous aortic heart valve results in a threefold lower rate of major vascular events and produces comparable rates of life-threatening and major bleeding events compared with the original device, researchers report in the July 2011 issue of JACC: Cardiovascular Interventions. By employing a smaller delivery system, the device could potentially make transcatheter aortic valve implantation (TAVI) suitable to a broader population of patients: those with peripheral artery disease (PAD).

The newer, smaller valve, known as the Sapien XT (Edwards Lifesciences, Irvine, CA), recently received CE mark approval and became commercially available in Europe, but no data are available pitting it against the first-generation Edwards Sapien valve. Therefore, researchers led by Antonio Colombo, MD, of the San Raffaele Scientific Institute (Milan, Italy), compared periprocedural and short-term outcomes with both devices in 120 consecutive patients who underwent TAVI at their center from November 2007 to April 2010.

Patients treated with the Sapien XT had a smaller minimal lumen diameter (MLD) of the iliofemoral arteries at the therapeutic access site compared with those treated with the first-generation Sapien valve (7.27 ± 1.09 mm vs. 7.94 ± 1.08 mm; P = 0.002). In addition, the ratio between the outer diameter of the sheath size and MLD of the vessel was significantly lower in the XT group (1.03 ± 0.15 vs. 1.13 ± 0.14 in the Sapien group; P = 0.001).

Substantial Difference in Major Vascular Events

Device success was similarly high in both the Sapien and Sapien XT groups (92.4% and 96.3%; P = 0.45). The rate of major vascular events was 23.3% overall, but it was threefold lower in XT patients. Life-threatening and major bleeding events did not differ between the 2 groups nor did minor vascular events. However, the XT group showed a trend toward less need for transfusion (table 1).

Table 1. Periprocedural and In-Hospital Outcomes

At 30 days, the Valve Academic Research Consortium (VARC) combined safety endpoint was reduced in the XT group compared with the first-generation Sapien group. This was attributable mainly to a lower rate of major vascular events. Other clinical outcomes were similar at 30 days (table 2). No patients suffered periprocedural MI and none required a repeat procedure for valve-related dysfunction.

Table 2. Thirty-Day Clinical Outcomes

^a VARC combined safety endpoint comprises all-cause mortality, major stroke, life-threatening (or disabling) bleeding, acute kidney injury (stage 3), periprocedural MI, major vascular complication, and repeat procedure for valve-related dysfunction.

At 30 days, the mean transaortic gradient on echocardiographic evaluation was approximately 10 mm Hg in both groups and aortic regurgitation was mild to moderate in 70.2% of XT patients vs. 76.3% of the other group.

In multivariable analyses, use of the XT valve emerged as the only significant independent predictor of reduced major vascular events (OR 0.25; 95% CI 0.09-0.67; P = 0.006), while female sex was associated with a trend toward increased events (OR 2.16; 95% CI 0.87-5.35; P = 0.09).

Implications for Broader Use

According to the authors, the results suggest that “vascular injury increases as the operator attempts the procedure with diseased peripheral vessels that have an inadequate size for the sheaths. Thus, the [XT] might have a broader clinical application, because it allows TAVI in patients with more severe peripheral vascular disease by reducing the ratio of sheath outer diameter size to vessel MLD but, at the same time, lowering the risk of [major vascular events].”

On univariate analysis, the ratio of the sheath outer diameter size to vessel MLD predicted major vascular events (OR 18.70; 95% CI 1.04-336.41; P = 0.04).

In a telephone interview with TCTMD, Augusto D. Pichard, MD, of Washington Hospital Center (Washington, DC), agreed that the XT may broaden the population of patients eligible for the valve, but he cautioned that the study offers a crucial teaching point.

“Making the valve smaller does not eliminate the vascular complications completely,” he said. “Operators still need to [heed] the precautions that we have learned so far and stick to large diameters and maybe we could have no vascular complications.”

Patient selection also plays a key role, Dr. Pichard added. “Sometimes with older patients and sicker patients, there is a temptation to squeeze it through vessels that really don’t allow for it, even with the smaller delivery system,” he said. “This pushing of the limits isn’t good and [can result in] complications.”

According to Dr. Pichard, the XT is gaining popularity in Europe, and while a randomized trial comparing it with the original Sapien would be important from a safety and efficacy perspective, it is unlikely to happen.

“The Europeans have been using the XT for over a year now and it will take [the United States] another couple of years to have it available to patients,” he said. “We are way behind the Europeans on percutaneous valve interventions, and they will never randomize patients to the older device because the smaller the delivery system, the simpler and safer and more widely available it is.”

The United States may be one step closer to catching up to the rest of the world tomorrow, when a Food and Drug Administration advisory panel is set to review the premarket approval application for the Sapien valve.

Study Details

The Edwards Sapien valve is a bovine pericardial leaflet valve mounted on a stainless steel stent. The XT has modified scallop-shaped leaflets and is mounted on a cobalt-chromium alloy stent with thinner struts that give it a lower profile. Both valves currently have 2 sizes: 23 and 26 mm.

The balloon-expandable transcatheter delivery system used with the original Sapien has the valve crimped directly on the balloon and allows introduction of the 23- or 26-mm valve with 22-Fr (outer diameter: 8.4 mm) and 24-Fr (outer diameter: 9.2 mm) sheaths. In comparison, the Sapien XT’s delivery system has the valve crimped on the catheter proximal to the inflatable balloon and is mounted on the balloon in the descending aorta. It allows for a reduction in sheath size to 18-Fr (outer diameter: 7.2 mm) for the 23-mm XT valve and 19-Fr (outer diameter: 7.5 mm) for the 26-mm valve.

 

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Source:
Mussardo M, Latib A, Chieffo A, et al. Periprocedural and short-term outcomes of transfemoral transcatheter aortic valve implantation with the Sapien XT as compared with the Edwards Sapien valve. J Am Coll Cardiol Intv. 2011;4:743-750.

 

 

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