Much Ado, But Not What To Do

In this issue of the Journal, Ussia and colleagues discuss their experience with using balloon aortic valvuloplasty (BAV) as a “bridge” to transcatheter aortic valve implantation (TAVI) in patients at high risk for TAVI.¹ They chose high-risk patients for BAV before TAVI, and followed with TAVI at varying intervals. Both functional and clinical status in their high-risk patients were improved enough to “raise” their stability to the level of the lower-risk patients. The study was not randomized, and thus not designed to evaluate or compare bridge BAV over direct TAVI in reducing the rates of in-hospital complications and early mortality in high-risk patients. After valvuloplasty, New York Heart Association (NYHA) functional class, mean pressure gradient and aortic valve area all improved. Bridging to TAVI with BAV may be a strategy in high-risk patients with symptomatic severe aortic stenosis. The report raises the issue of how little we really know about the usefulness of BAV. The technique was originally developed in the 1980s for treatment of patients who were not ideal candidates for aortic valve replacement surgery and was quickly adopted for treatment of many patients because of the increase of aortic valve area that improved the symptomatic status of patients. The use of BAV had enthusiastic supporters and deprecating detractors. Overall, the detractors ultimately owned the day. Despite early optimism for BAV, it soon became apparent that clinical improvement was short-lived. For most patients, BAV was an option only if they had a prohibitively high surgical risk for valve replacement. In most centers, the procedure was virtually abandoned except for patients in severe congestive heart failure secondary to aortic stenosis or patients in cardiogenic shock who were “bridged” to surgery with BAV. TAVI, of course, changed all that. BAV was reinvented as a procedure necessary to allow the transcatheter valve to pass through the stenotic native valve with less difficulty. Not only that, but in patients with borderline low ejection fraction, low cardiac output and calculated aortic valve areas that appeared to show critical stenosis, BAV has once again been used to evaluate whether the left ventricle can improve if aortic stenosis is relieved (albeit briefly) and whether a candidate for TAVI indeed should be offered the procedure with any chance of left ventricular recovery. Despite all this, how much do we really know about the results of BAV compared to other therapies, especially TAVI? So far, we don’t know as much as we would like. When BAV was in its clinical heyday, there were a number of registries, including one sponsored by the National Heart, Lung, and Blood Institute (NHLBI), that chronicled the use of BAV in the United States and documented outcomes. It is from these data that we understood that the mortality risk over time of aortic stenosis did not seem to be affected by BAV, and that 1-year mortality with and without BAV ranged near the historical 50%. In addition to the registry data, multiple individual sites reported outcomes of patients undergoing BAV for critical aortic stenosis, but there were never any randomized trials done to answer the question of BAV’s efficacy compared to other therapies. We will, however, in the next year understand a lot more about that specific question. Part of the randomized PARTNER Trial is a group of “non-surgical” candidates. If their ileo-femoral arteries are large enough to accommodate the appropriate transcatheter sheath, they are randomized to either TAVI or “ongoing medical therapy,” which includes multiple BAV procedures for most. The outcomes of this portion of PARTNER will be a welcome addition to our understanding of what BAV can and cannot accomplish. My hope is that the trial will show that TAVI is superior to BAV (and ongoing medical therapy) in such patients, since the track record from the registries of 20 years ago seemed to show no change from the natural history of aortic stenosis. But regardless of the outcome, it seems that BAV will be around as a technique for the foreseeable future. It seems to provide a “bridge” to both to surgery and possibly to TAVI as well, and certainly, if we continue to use TAVI in the next years, it will be needed to prepare the valve for transcatheter replacement.

Reference

1. Ussia GP, Capodanno D, Barbanti M, et al. Balloon aortic valvuloplasty for severe aortic stenosis as a bridge to high-risk transcatheter aortic valve implantation. J Invasive Cardiol 2010;22:162–166.

_________________________________________
From Emory University Hospital, Atlanta, Georgia. The author reports no conflicts of interest regarding the content herein. Address for correspondence: Peter C. Block, MD, Emory University Hospital, 1364 Clifton Road N.E., Atlanta, GA 30322. E-mail: pblock@emory.edu