Single-Center Experience Shows Evolution of CoreValve Procedure Over Time

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As clinicians have gained experience with transcatheter aortic valve implantation (TAVI) using the CoreValve system, the procedure has become safer—with fewer severe bleeds and cerebrovascular events—as well as less complex, although overall complications remain troublesome, according to a small single-center study published online April 11, 2011, ahead of print in the American Journal of Cardiology.

Researchers led by Peter P. de Jaegere, MD, PhD, of Erasmus Medical Center (Rotterdam, The Netherlands), analyzed 165 consecutive patients with severe aortic stenosis who underwent TAVI with the CoreValve device (Medtronic, Minneapolis, MN) at their institution, dividing them into 2 time periods: November 2005 to December 2007 (n = 33), and January 2008 to October 2010 (n = 132). These time periods were chosen because Erasmus Medical Center received certification from Medtronic that the institution and team were qualified to perform TAVI without any assistance or proctoring in January 2008.

The first 5 patients were treated with the second-generation CoreValve device, which used a 21-Fr delivery catheter during a hybrid surgical procedure. The rest of the patients received the third-generation device, delivered using an 18-Fr arterial sheath. By October 2006 the procedure became a solely percutaneous operation, with the gradual omission of circulatory support by December 2006.

From the early to the late period, patient selection clearly evolved, with patients having less NYHA class III or IV heart failure, less hypertension, and less aortic regurgitation grade III or greater (table 1).

Table 1. Baseline Characteristics

In terms of procedural characteristics, the late cohort patients more frequently underwent a true percutaneous transfemoral approach (98% vs. 82%; P = 0.002) without circulatory support (96% vs. 67%; P < 0.001), but more often received concomitant PCI (11% vs. 0; P = 0.042). There also was a reduction in the use of contrast in the late cohort patients (176 ml vs. 211 ml; P = 0.041).

In terms of clinical outcomes, there was no difference between the groups in all-cause death at 30 days, except for a nonsignificant increase in the late cohort (3% vs. 11%; P = 0.20). CV death also was similar between the early (3%) and late (8%) cohorts (P = 0.47).

The combined safety endpoint, defined by the Valve Academic Research Consortium (all-cause death, major stroke, life-threatening bleeding, acute kidney injury, periprocedural MI, and repeat procedure for valve-related dysfunction), at 30 days was decreased in the late cohort, but the difference did not reach statistical significance (17% vs. 30%; P = 0.076). Other in-hospital complications, meanwhile, also were reduced in the late cohort, including cerebrovascular complications (driven by fewer TIAs), and life-threatening bleeding, although overall bleeding did not show a difference (table 2).

Table 2. In-Hospital Clinical Outcomes

Late cohort patients had a lower mean aortic gradient than early cohort patients (9 ± 3 vs. 11 ± 6; P = 0.013) and less aortic regurgitation grade III or greater (12% vs. 30%; P = 0.010) at predischarge echocardiography.

The researchers conclude that over time, “TAVI became significantly less complex and was associated with better results . . . but remained associated with a high frequency of periprocedural major cardiovascular complications.”

It is unclear, they add, which of the following factors contributed to the observed improvement in clinical outcomes:

• Changes in baseline patient risk
• Improvements in technology and procedure
• Omission of circulatory support
• Increased operator experience
• Improved postoperative care

Nevertheless, “we believe that the continuous improvement can more likely be explained by the increasing operator/institutional experience, and not the reduction in the size of the delivery catheter,” despite the reduced bleeding risk that came with the latter development, the researchers note.

Risks Remain

In a telephone interview with TCTMD, Peter C. Block, MD, of the Emory University School of Medicine (Atlanta, GA), summed up what he felt to be the main message from the study: “This is not easy.”

“Over time, operators learn how to minimize risk by more careful choice of patients and more careful evaluation of those things that produce risk, particularly the peripheral vascular issues, so that they become better at avoiding those patients who would likely have difficulty with bleeding and so forth,” Dr. Block continued. “But the bottom line is that despite all that, there are still significant risks associated with the procedure.”

He added that while the complication rates were “higher than you’d like to see,” this did not translate to an unusually high mortality rate. “On balance, this is a procedure that is complex, not easy to do, that demands careful selection and operator experience, and careful operator thought intraprocedurally,” he said.

Patient Selection Takes Center Stage

Dr. Block noted that he has performed about 160 TAVI procedures with the Edwards Sapien aortic valve device (Edwards Lifesciences, Irvine, CA), and none with the CoreValve. He described similar patient selection issues. “We’ve found the same thing with the Edwards prosthesis, that we are less enthusiastic about undertaking a borderline patient simply because we fear that the risks do not justify the benefit, particularly in elderly patients,” Dr. Block said.

He acknowledged that as patient selection becomes more tailored, some high-risk, inoperable patients may be denied the procedure. “I think the answer to some of that is, ‘yes,’” Dr. Block responded. “We’re all starting to get into this issue of, now that we know we can do the procedure, when should we really do it? And how do we pick the patients to whom we offer this technology?”

Ultimately, he said, all these issues should be discussed thoroughly with the patient. “It’s critical the patient understands the risk and benefit before going forward,” Dr. Block stressed. “Many patients, for instance, when you tell them they have something like a 10% risk of stroke because they have a terrible aorta, they’ll say ‘It’s not worth it to me, I’d rather die,’ because to them, a stroke is worse than dying.”

 

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Source:
Nuis R-J, van Mieghem NM, van der Boon RM, et al. Effect of experience on results of transcatheter aortic valve implantation using a Medtronic CoreValve system. Am J Cardiol. 2011;Epub ahead of print.

 

Disclosures:

• Dr. de Jaegere makes no statement regarding conflicts of interest.
• Dr. Block reports serving as an investigator for the Edwards aortic valve system, and as a consultant for Direct Flow Medical and Medtronic.

 

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