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For patients with a degenerated surgically implanted aortic bioprosthesis who are not candidates for reoperation, transarterial implantation of a CoreValve replacement may be a safe and effective option, suggest results of a small series published online September 27, 2011, ahead of print in Circulation: Cardiovascular Interventions. 

Researchers led by Fleur Descoutures, MD, of Assistance Publique-Hôpitaux de Paris (Paris, France), analyzed data from 10 patients who received the Corevalve system (Medtronic, Minneapolis, MN) to replace a failed surgically implanted aortic bioprosthesis. The cohort represented 4% of the 241 patients who underwent transcatheter aortic valve replacement at their institution between October 2006 and November 2010. 

Transfemoral the Predominant Approach

Transfemoral access was used in 9 patients, while 1 patient underwent a subclavian approach. Six patients had general anesthesia; the other 4 received local anesthesia or conscious sedation.

The 26-mm Corevalve bioprosthesis was implanted in 8 patients, while the remaining 2 patients received the 29-mm model.  All procedures were successful, with no conversions to surgery, and deployment was characterized as “correct.”  No paraprospthetic or central aortic leak grade greater than 2+ was observed. The final mean gradient was 13 ± 7 mm Hg.

Periprocedural complications included 1 case each of

• In-hospital death
• Stroke
• Heart block requiring implantation of a permanent pacemaker

The 30-day combined safety endpoint occurred in 2 patients. As defined by the Valve Academic Research Consortium (VARC), this includes all-cause mortality, major stroke, life-threatening bleeding, acute kidney injury, periprocedural MI, major vascular complications, or a repeat procedure for valve-related dysfunction.

Hemodynamic Improvement

Before discharge, transthoracic echocardiography showed a mean transprosthetic gradient of 13 ± 7 mm Hg. On average, the mean gradient of stenosed bioprostheses decreased from 58 ± 16 mm Hg to 17 ± 7 mm Hg (P = 0.01). The mean final prosthesis area was 1.6 ± 0.4 cm². Paravalvular leaks were absent or trivial in all but 1 patient, who had a highly calcified and regurgitant homograft.

At 30 days, the mean gradient and mean prosthetic area were largely unchanged.

At a median follow-up of 150 days, there were no additional deaths or other events. Moreover, NYHA heart failure status had improved to class I or II in 9 of the 10 patients.

“[T]hese data are preliminary and will require further confirmation by larger series and longer follow-up,” the authors say. “If mid- and long-term outcomes remain favorable, this will have important clinical implications for treatment strategies of [aortic stenosis] in high-risk patients.”

“The more we learn about this [strategy], the better,” added Peter C. Block, MD, of Emory University Hospital (Atlanta, GA), in a telephone interview with TCTMD. But in fact, the feasibility of valve-in-valve implantation has already been shown using the Edwards Sapien (Edwards Lifesciences; Irvine, CA) and other bioprostheses, and not only in the aortic valve but also the mitral, pulmonary, and tricuspid valves (eg, Webb JG et al, Circulation. 2010;121:1848-1857), he noted.

Appropriate Sizing Can Be Tricky

Addressing the technical challenges of the procedure, Dr. Block said determining the true internal diameter of a failed bioprosthetic valve is critical to selecting the proper size of a replacement, but that can be tricky. “Each manufacturer has a different way of assigning a number to their valves, so a ‘23-mm valve’ may not have an internal diameter anywhere near 23 mm,” he commented. “And a simple measurement on angiography or CT [imaging] may not give you the answer.”

Jeffrey W. Moses, MD, of Weill Cornell Medical College (New York, NY), agreed. Optimizing hemodynamics depends on appropriate sizing, he told TCTMD in a telephone interview, and the current bioprostheses were not designed for this scenario. “[The investigators] reported low gradients here, but gradients with CoreValve have been higher [in other series], which suggests they’re not getting optimal expansion,” he said. That can diminish the durability of the new bioprosthesis, he added.

Another consideration is the configuration of the device, Dr. Moses said. For example, if the leaflets are not positioned inside the stent structure, it can lead to obstruction of the coronary arteries, he observed.

With regard to clinical safety, Dr. Block said that although numbers in a small series are unreliable indicators, the investigators seem to “gloss over the fact that, with 1 case each of death, stroke, and heart block, they had a 30% adverse event rate.”

It is difficult to compare the performance of CoreValve with the rival Edwards prostheses in the valve-in-valve setting, Dr. Moses added, in part because almost all the former have been delivered transfemorally, while the latter have been implanted with a mix of transapical and transfemoral approaches. However, the desire to avoid predilation and the concomitant risk of embolization may favor the transapical approach available with the Edwards valve, he said.

Dr. Block said the self-expanding CoreValve may confer a small advantage in that it allows minor adjustments before final positioning. On the other hand, the risk of heart block is an important ongoing problem with the Medtronic device, he noted, one whose true dimension will become clearer as data emerge from the ongoing Medtronic CoreValve US Pivotal trial. 

‘It’s a Godsend’

Thus far, almost no valve-in-valve procedures have been performed in the United States, Dr. Block commented. “But if the Edwards valve is approved here, as seems likely in a few months [on July 20, 2011, a U.S. Food and Drug Administration advisory panel recommended approval for inoperable patients], I think you will see it being used in an off-label way in patients with degenerated [surgically implanted] bioprostheses,” he said, although he was skeptical that reimbursement for such use would be forthcoming.

“We’re just beginning to get a rudimentary understanding of [the valve-in-valve procedure],” Dr. Moses said, “and there’s a big learning curve. We need more data, especially about durability. Prospective multicenter registries are going to be essential.”

“The good news is that this procedure is feasible, and therefore patients [with failed surgical bioprostheses] now have an option,” Dr. Block concluded. “Without intervention, their prognosis is dismal.” 

Dr. Moses echoed that sentiment. “For a lot of patients with comorbidities and multiple [bioprosthesis] surgeries, [the valve-in-valve procedure] is a godsend,” he said.

Study Details

The mean age of the valve-in-valve patients was 75 ± 10 years, and all had New York Heart Association (NYHA) class III or IV congestive heart failure. Their mean Society of Thoracic Surgeons (STS) score was 6 ± 4%. Although 8 patients had an STS score less than 10% (ie, below the standard cutoff for high risk), they were deemed to be at high risk for reoperation based on clinical judgment.

To avoid the risk of leaflet fracture or embolization, no balloon predilatation was used. Rapid ventricular pacing (120-160 bpm) was used during deployment, especially in the presence of regurgitant bioprostheses, to reduce cardiac motion and facilitate optimal positioning.

Related Stories:

• Early Results of ‘Valve-in-Valve’ Implantation for Failed Bioprostheses Encouraging
• Single-Center Experience Shows Evolution of CoreValve Procedure Over Time
• ‘Valve-in-Valve’ Technique Effective in Treating CoreValve Leaks