Balloon Predilation for TAVR: Over-Inflated or Under-Rated?

In their article, “Sapien 3 Transcatheter Aortic Valve Implantation With Moderate or Without Predilation,” Abramowitz et al¹ evaluate the impact of no predilation compared with undersized predilation for transcatheter aortic valve replacement (TAVR). They characterize a “regular” predilation approach as use of 20 mm, 23 mm, and 25 mm balloons for balloon aortic valvuloplasty (BAV) for 23 mm, 26 mm, and 29 mm valves, respectively. Omission of predilation was associated with small reductions in fluoroscopy time and contrast use with no other clinical consequences.

The rationale for BAV prior to TAVR is to facilitate device introduction within the diseased aortic valve, enabling TAVR device expansion by reducing radial counterforces. On the other hand, BAV may result in stroke from distal embolization,² conduction disturbances,³ and aortic regurgitation with intraprocedural hemodynamic instability.⁴ The rationale for use of undersized predilation was described in a prior report by these authors,⁵ who noted that new-generation devices with reduced profile sizes and increased radial forces, along with advances in the pre-TAVR imaging techniques, have set the background for moderate or no predilation. Further, smaller BAV balloon size has been associated with lower new permanent pacemaker rates.⁶

Their moderate BAV predilation group used small-sized balloons with a diameter of ≤18 mm for the 23 mm implanted valves and of ≤22 mm for the 26 or 29 mm implanted valves. The mean balloon diameter was 15 mm, with a balloon/annulus ratio of 0.62. Might this be considered a “sham” BAV? The occasional TAVR patient may have such extreme stenosis or calcification that simply crossing with a TAVR system is facilitated by minimalist predilation. These authors applied undersized predilation selectively in these cases. The patients selected for predilation had smaller valve area, higher gradients, and more calcification. The authors conclude that Sapien 3 balloon-expandable TAVR with moderate or without balloon predilation is feasible and safe and that omission of predilation in appropriate cases was associated with reduced fluoroscopy time and total contrast used without affecting procedural success. The other side of this conclusion is that predilation may be helpful for selected cases and does not bring added major risks. 

Does predilation diminish the need for postdilation? This has been the case in prior studies.⁷ In this report, the need for postdilation was 6.5% overall and not different for no predilation versus undersized predilation. The uncertainty about whether more aggressive predilation would diminish the need for postdilation is clouded by better TAVR device size selection based on computed tomography analysis in addition to the impact of BAV. The finding of more or fewer neurologic events after predilation or postdilation has been inconsistent and is another uncertainty in this discussion.⁸ 

Several questions remain unanswered. Can predilation be completely abandoned? Is more aggressive predilation better or worse than nothing or minimal predilation with the current generation of balloon-expandable valve? Are these results generalizable to other TAVR platforms? Are bicuspid valves a different substrate for predilation?

This last question has increasing importance as we move toward lower-risk TAVR candidates, since the frequency of bicuspid aortic stenosis rises among the low-risk group. The experience with TAVR in bicuspid aortic stenosis was not as good as in tricuspid aortic stenosis with earlier-generation TAVR devices, but seems to be improving with newer TAVR technology and importantly with better understanding of computed tomography analysis for valve size selection. How important is predilation in this context? 

The importance of predilation for devices other than Sapien 3 also requires further definition. Balloon dilation is an inherent part of the Sapien procedure, while the self-expanding CoreValve and the mechanically expandable Lotus valve have significantly different properties. The routine practice of maintaining peak inflation of the Sapien delivery balloon for valve deployment by default imparts some degree of BAV to this procedure. The CoreValve device is at the opposite end of the spectrum. While it is clearly feasible to omit predilation before CoreValve implantation, there may be a significantly greater need for postdilation.⁹ The mechanically expandable Lotus valve is unique. The frame expansion is necessarily gradual due to the force limit inherent in the delivery system, so the increased device diameter is delivered to the native annulus slowly. Expansion of the annulus may be facilitated by predilation, but it is also possible that the Lotus device itself functions as a “metal BAV.” There is not yet enough experience with this platform to understand the need for predilation.

The importance of predilation, the trade-off with postdilation, and the impact of BAV on complication rates is a moving target. This analysis shows that the newest iteration of the Sapien family, the Sapien 3, can be delivered without a preprocedure BAV if desired. The safety of BAV with balloon/annulus ratio closer to 1.0, and the importance of predilation for other TAVR devices and some specific patient subsets remain open questions. Both technology and techniques are changing rapidly enough that this debate will continue for some time. 

References

1.    Abramowitz Y, Jilaihawi H, Chakravarty T, et al. Sapien 3 transcatheter aortic valve implantation with moderate or without predilation. J Invasive Cardiol. 2016;28:421-426. 

2.    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. JACC Cardiovasc Interv. 2015;8:1608-1613. Epub 2015 Sep 17.

3.    Laynez A, Ben-Dor I, Hauville C, et al. Frequency of cardiac conduction disturbances after balloon aortic valvuloplasty. Am J Cardiol. 2011;108:1311-1315. Epub 2011 Aug 18.

4.    Khawaja MZ, Sohal M, Valli H, et al. Standalone balloon aortic valvuloplasty: indications and outcomes from the UK in the transcatheter valve era. Catheter Cardiovasc Interv. 2013;81:366-373. 

5.    Abramowitz Y, Jilaihawi H, Chakravarty T, et al. Feasibility and safety of balloon-expandable transcatheter aortic valve implantation with moderate or without predilatation. EuroIntervention. 2016;11:1132-1139.

6.    Lange P, Greif M, Vogel A, et al. Reduction of pacemaker implantation rates after CoreValve implantation by moderate predilatation. EuroIntervention. 2014;9:1151-1157.

7.    Pagnesi M, Jabbour RJ, Latib A, et al. Usefulness of predilation before transcatheter aortic valve implantation. Am J Cardiol. 2016;118:107-112. Epub 2016 Apr 21.

8.    Kempfert J, Meyer A, Kim WK, et al. First experience without pre-ballooning in transapical aortic valve implantation: a propensity score-matched analysis. Eur J Cardiothorac Surg. 2015;47:31-38; discussion 38. Epub 2014 Mar 27.

9.    Barbanti M, Petronio AS, Capodanno D, et al. Impact of balloon postdilation on clinical outcomes after transcatheter aortic valve replacement with the self-expanding CoreValve prosthesis. JACC Cardiovasc Interv. 2014;7:1014-1021.

From the NorthShore University HealthSystem, Evanston, Illinois and Houston Methodist DeBakey Heart & Vascular Center, Houston, Texas.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Feldman reports grants and personal fees from Abbott Vascular, Boston Scientific, Edwards Lifesciences, and Gore. Dr Reardon reports advisory board fees from Medtronic, paid directly to his institution (no personal fees). 

Address for correspondence: Ted Feldman, MD, FESC, FACC, MSCAI, Evanston Hospital Cardiology Division-Walgreen Building 3rd Floor, 2650 Ridge Ave, Evanston, IL 60201. Email: tfeldman@tfeldman.org