The Balloon Aortic Valvuloplasty Makeover: From "Treatment" Procedure to "Bridge" Procedure

Severe aortic stenosis is a progressive condition associated with poor functional capacity and quality of life. Without definitive treatment, symptomatic severe aortic stenosis is associated with significantly reduced survival. While surgical aortic valve replacement (SAVR) was long regarded as the gold standard, it was only a suitable option for patients who were adequate surgical candidates. In the EURO Heart Survey, nearly one-third of patients were too sick to receive surgical valve replacement.¹ Patients were felt to be poor surgical candidates due to advanced age, short life expectancy, and comorbidities including pulmonary disease and renal failure. Transcatheter aortic valve replacement (TAVR) has since emerged as a viable option for those patients who were previously deemed non-surgical candidates. The pivotal trials in TAVR showed that it was a safe, less invasive, and efficacious option for patients who were at higher surgical risk. Patients undergoing TAVR had superior outcomes compared with medical therapy alone and equivalent outcomes to patients undergoing surgical replacement.^2,3 The Transcatheter Valve Therapy (TVT) registry has revealed that since initial United States Food and Drug Administration approval in 2012, the rates of TAVR have continued to double on a yearly basis, with a doubling in the number of centers performing the procedure.⁴ The introduction and rise in TAVR has been built on the foundations and experiences of balloon aortic valvuloplasty (BAV). 

Percutaneous balloon aortic valvuloplasty as a treatment option initially emerged in the 1980s for patients with severe aortic stenosis who were not surgical candidates. There was enthusiasm for more widespread use after reports of improvements in symptoms and valve hemodynamics. The NHLBI balloon valvuloplasty registry systematically fol-lowed 674 patients over a 24-month period and revealed that the majority of patients had hemodynamic improve-ments in the degree of their aortic stenosis. Although mortality from the proce-dure was fairly low, there was significant morbidity associated with BAV in this sick and elderly population. Nearly one-quarter of patients had a significant complication in the first 24 hours.⁵ The most common complications included cardiac death, transfusion requirements, vascular access com-plications, and stroke. Furthermore, the effects of the procedure were non-durable and there was a high rate of restenosis over a period of weeks to months. The initial excitement for BAV was thus tempered by the limited benefits and high complication rate associated with the procedure, and it remained relegated to use in inoperable patients for palliative purposes. 

The advent of TAVR in the 2000s resulted in a resurgence of interest in balloon valvuloplasty. In a study by Kumar et al in this month’s Journal of Invasive Cardiology, the authors review the evolution of the trends, indications, outcomes, and complications associated with BAV in the era of TAVR.⁶ Overall, the patient population in the contemporary era is a sicker population, with an increased frequency of multiple comorbidities. Most striking has been the shift in indications for the procedure. Prior to TAVR, nearly all of the procedures were performed for palliative purposes, whereas in the contemporary era the procedure is increasingly being done as a bridge to either SAVR or TAVR. As expected, the hemodynamic outcomes from valvuloplasty have remained fairly similar between the two time periods. Most impressive has been the dramatic decrease in procedural complications: procedural death, in-hospital mortality, and vascular complications have all significantly reduced in the TAVR era. 

A change in indication for the procedure is one of the key reasons for its resurgence. Thus, previously, it was largely regarded as a palliative procedure whereas now valvuloplasty can be offered as a bridge to treatment or a decision. Often in patients with multiple comorbidities, such as in patients with severe concomitant lung disease, it can be unclear whether symptoms are truly secondary to severe aortic stenosis. In this patient group, valvuloplasty provides a reasonable trial option; if there is no significant improvement in symptoms from valvuloplasty, one can likely assume that there will be little benefit from TAVR. In patients with multiple comorbidities undergoing urgent non-cardiac surgery, valvuloplasty can be performed as a bridge to allow them to safely undergo surgery until a more durable solution (SAVR or TAVR). In patients with cardiogenic shock, severe sepsis, or with an uncertain life expectancy, BAV may assist in getting over their acute illness. The control arm of the PARTNER 1B trial (inoperable cohort) deserves special mention here. Although this arm included patients who were medically managed, nearly 85% received BAV at some point during the trial. These patients did experience short-term improvements in functional capacity and survival, but there was no significant difference at 6 months.⁷ As expected, the rates of vascular complications and bleeding were significantly higher in the BAV group compared with the non-BAV group; however, interestingly the stroke rate was higher in the untreated group (2.6% vs 1.0%). The short-term survival benefit in the BAV group further emphasized the role of this procedure as a bridge option prior to definitive treatment. 

This meta-analysis also illustrates that complication rates have decreased in the TAVR era. There are likely two main reasons for this. First, the advent of TAVR has brought newer techniques and modalities into routine use. For instance, prior to the introduction of TAVR, rapid pacing was rarely performed during valvuloplasty, while now it has become commonplace and likely helps with more efficient expansion of the stenotic valve. The TVT registry also revealed an increase in the frequency of computed tomography scans being used to appropriately size the aortic valve annulus, which may translate to the increased frequency of single balloon use during valvuloplasty and decrease in aortic root damage. Also, improved experience with vascular access has likely contributed to the improved risk profile with valvuloplasty. Operators are now much more experienced and comfortable with large-sheath delivery systems and closure devices, which has significantly decreased the incidence of vascular complications. Indeed, as TAVR technology has improved, the size of delivery systems has decreased and the vascular complication rate has dropped from 5.6% to 4.7% in 2014.⁴ Second, with the increase in frequency as a “bridge” procedure rather than as a “treatment” procedure, operators are avoiding overly aggressive inflations, which helps reduce the complication rates of annular rupture and aortic regurgitation. This may also translate to a decrease in the vascular complication rate as smaller balloons require smaller sheaths for delivery. 

Cost-effectiveness is not directly addressed here, but is likely dominated by the high current cost of the TAVR valves. However, this meta-analysis does open the door to an interesting debate as TAVR technology continues to evolve. Contemporary valves – for instance, Edwards Sapien S3 and Medtronic CoreValve Evolut R – have delivery sheath sizes (14 Fr and 16 Fr) that are similar to those utilized for balloon aortic valvuloplasty (10-12 Fr), and are a far cry from the days of 22 and 24 Fr sheaths required for first-generation devices. In recent analyses, the latest-generation TAVR devices have complication rates that are comparable to those reported with valvuloplasty in the Kumar et al study. For instance, 30-day mortality and vascular complication rates in the PARTNER II S3 high-risk registry were 2.2% and 5.1%, respectively, which are comparable to the rates reported in this analysis (4.6% in-hospital mortality; 4.0% vascular complications).⁸ The populations are obviously not directly comparable, but one wonders if the role of valvuloplasty as a bridging procedure may diminish going forward, particularly if the device cost decreases significantly as well. A dedicated registry for valvuloplasty procedures, similar to the STS/TVT registry for TAVR, and perhaps even a head-to-head trial, are thus required to allow for an informed debate on this issue. 

In conclusion, BAV has evolved over the years. It remains an appropriate procedure for palliative purposes and is increasingly being utilized as a bridge for patients who are not yet suitable candidates for SAVR or TAVR. Many of the advances in TAVR technology and increasing institutional and operator comfort level with TAVR have also led to decreases in the previously high complication rates associated with BAV.        

References

1.    Iung B, Baron G, Butchart EG, et al. A prospective survey of patients with valvular heart disease in Europe: the Euro Heart Survey on Valvular Heart Disease. Eur Heart J. 2003;24:1231-1243.

2.    Leon MB, Smith CR, Mack M, et al. Transcatheter aortic-valve implantation for aortic stenosis in patients who cannot undergo surgery. N Engl J Med. 2010;363:1597-1607.

3.    Kumbhani DJ, Banerjee S. 3-Year Results of a TAVR Trial in High Surgical Risk Patients. J Am Coll Cardiol. 2016;67:2575-2577.

4.    Holmes DR Jr, Nishimura RA, Grover FL, et al. Annual outcomes with transcatheter valve therapy: from the STS/ACC TVT registry. J Am Coll Cardiol. 2015;66:2813-2823.

5.    Percutaneous balloon aortic valvuloplasty. Acute and 30-day follow-up results in 674 patients from the NHLBI Balloon Valvuloplasty Registry. Circulation. 1991;84:2383-2397.

6.    Kumar A, Paniagua D, Hira RS, Alam M, Denktas AE, Jneid H.  Balloon aortic valvuloplasty in the transcatheter aortic valve replacement era. J Invasive Cardiol. 2016;28:341-348.

7.    Kapadia S, Stewart WJ, Anderson WN, et al. Outcomes of inoperable symptomatic aortic stenosis patients not undergoing aortic valve replacement: insight into the impact of balloon aortic valvuloplasty from the PARTNER trial (Placement of AoRtic TraNscathetER Valve trial). JACC Cardiovasc Interv. 2015;8:324-333.

8.    Kodali S, Thourani VH, White J, et al. Early clinical and echocardiographic outcomes after SAPIEN 3 transcatheter aortic valve replacement in inoperable, high-risk, and intermediate-risk patients with aortic stenosis. Eur Heart J. 2016 Mar 31 (Epub ahead of print).

From UT Southwestern Medical Center, Dallas, Texas.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Kumbhani reports grants and personal fees from the American College of Cardiology, outside the submitted work. Dr Koshy reports no conflicts of interest regarding the content herein.

Address for correspondence: Dharam J. Kumbhani, MD, SM, MRCP, FACC, FAHA, FSCAI, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9047. Email: dharam@post.harvard.edu