About One-Third of CoreValve Patients Require a Permanent Pacemaker

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Approximately 1 in 3 patients with severe aortic stenosis who undergo transcatheter aortic valve implantation (TAVI) with the CoreValve device will require a permanent pacemaker within 30 days of the procedure, according to a British study published online February 21, 2011, ahead of print in Circulation. The findings echo those of a Spanish study published recently in Revista Española de Cardiología that found a similar need for pacemakers in such patients.

In the first study, researchers led by David J. Hildick-Smith, MD, of the Sussex Cardiac Centre (Brighton, United Kingdom), evaluated data from 243 patients in the United Kingdom and Ireland who were implanted with the CoreValve Revalving System (CoreValve, Medtronic, Luxembourg) between April 2007 and June 2009.

Overall, 81 patients (33.3%) required a permanent pacemaker within 30 days, with a median time to insertion of 4.0 days (interquartile range, 2.0-7.75 days).

In multivariable regression analysis, the strongest independent predictors of the need for a permanent pacemaker were peri-implantation atrioventricular block and use of balloon predilatation. Also significant were longer QRS duration, use of the larger (29-mm) prosthesis, and greater interventricular septum diameter (table 1).

Table 1. Factors Associated with Need for Permanent Pacemaker

Abbreviation: AV, atrioventricular.

Pacemaker Rate Reflects Limitations of Current Technology

According to the authors, the findings regarding the need for permanent pacemaker implantation are in line with previous smaller studies that have reported rates of between 18% and 40%.

In an e-mail communication with TCTMD, Dr. Hildick-Smith said the need for a pacemaker in these high-risk patients reflects the limitations of the current technology. “Let’s not forget the incredible impact TAVI has had for patients,” he said. “They need to know, though, that there is a 1 in 3 chance of needing a pacemaker in addition when the CoreValve is implanted. The rate is lower for the Edwards valve, but this has implantation issues that are more complex than for the CoreValve. You win some, you lose some.”

Dr. Hildick-Smith added that although some studies have reported lower rates of pacing, he believes the rate of 1 in 3 is real because many of those publications had less complete individual patient follow-up.

Similar Findings from Spain

In the second study, Antonio J. Muñoz-García, MD, of Virgen de la Victoria Hospital (Malaga, Spain), and colleagues report on 61 patients who received a CoreValve prosthesis between April 2008 and October 2009.

Similar to the UK study, the rate of need for a pacemaker was about 1 in 3 (34.4%). Most of the devices were implanted between 2 and 5 days after the procedure.

The factor most associated with the need for a pacemaker was greater depth of prosthesis implantation in the left ventricular outflow tract (mean 13 ± 2.5 mm vs. 8.8 ± 2.8 mm in those not requiring a pacemaker; P < 0.001). No differences were found between those who did and did not need a pacemaker in the dimensions of the aortic annulus or the prosthesis/annulus ratio, the degree of left ventricular hypertrophy, or valve calcification.

Although patients with right bundle-branch block required a pacemaker more often than those with left bundle-branch block (47.6% vs. 28.5%), in multivariable analysis the depth of the prosthesis in the left ventricular outflow tract was the only factor that predicted need for a pacemaker (OR 1.9; 95% CI 1.19-3.05; P = 0.007). A cutpoint of 11.1 mm for prosthesis depth had a sensitivity of 81% and a specificity of 84.6% for predicting the need for a pacemaker.

Dr. Muñoz-García and colleagues say their data suggest that a higher position of the aortic prosthesis might reduce the incidence of electrical changes and the need for a pacemaker.

“In fact, implant of the CoreValve prosthetic valve is considered optimal when the depth of the prosthesis in the [left ventricular outflow tract] is 6 mm. Further specific studies are required to examine these aspects and determine the indications for the implant of a definitive pacemaker in these patients,” they write.

In addition, the study authors say that although right bundle-branch block was not found to be a predictor of pacemaker need, the findings suggest that special consideration must be given to those patients with the condition before the procedure.

Did the Learning Curve Play a Role?

“I think it’s clear that the design of the CoreValve device results in conducting system abnormalities in some patients and these 2 studies are helpful in understanding what the risk factors for those outcomes are,” said Ted Feldman, MD, of Evanston Hospital (Evanston, IL), in a telephone interview with TCTMD.

“What isn’t clear is whether there is a learning curve because these are patients who were treated several years ago. It will be very important to see if, as a community, those who are implanting the CoreValve are figuring out how to minimize the heart block incidence,” he said. “Also, we have yet to see a lot of results with the improved CoreValve delivery system and whether that will have an important effect on conducting system compromise.”

Dr. Feldman added that since many conduction problems resolve on their own, he was impressed that there were a significant number of fairly late decisions to place pacemakers, adding that, “it’s hard to say whether the decision of when to implant is the result of clinicians becoming more proactive about implanting at any sign of a problem versus taking a wait-and-see approach.”

For his part, Dr. Hildick-Smith said the problem with waiting is that it is not economically viable to keep patients in the hospital, nor is it sensible to send them home and hope that they will not come back with heart block.

“It’s much better to put the pacemaker in—it’s a very low risk procedure—and accept that many patients will not need it in 3 months’ time than to cross you fingers [and not implant] just to keep your pacing rate low,” he added.

 

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Sources:
1. Khawaja MZ, Rajani R, Cook A, et al. Permanent pacemaker insertion after CoreValve transcatheter aortic valve implantation: Incidence and contributing factors (the UK CoreValve Collaborative). Circulation. 2011;123:951-960.

2. Muñoz-García AJ, Hernández-García JM, Jiménez-Navarro MF, et al. Changes in atrioventricular conduction and predictors of pacemaker need after percutaneous implantation of the CoreValve aortic valve prosthesis. Rev Esp Cardiol. 2010;63:1444-1451.

 

 

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