TAVR-Associated Aortic Root Rupture Hazardous but Predictable

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Aortic root rupture that occurs during transcatheter aortic valve replacement (TAVR) using balloon-expandable prostheses carries a heightened risk of in-hospital adverse events but can be predicted by anatomic and procedural factors. The findings, from a small multicenter study, were published online June 7, 2013, ahead of print in Circulation. 

Jonathon Leipsic, MD, of St. Paul’s Hospital (Vancouver, Canada), and colleagues enrolled 31 consecutive patients who experienced left ventricular outflow tract (LVOT)/annular/aortic root rupture while receiving Sapien or Sapien XT devices (Edwards Lifesciences, Irvine, CA) at 16 centers worldwide. This cohort was caliper-matched to a sample of 31 patients without annular rupture who had similar baseline characteristics and served as controls. 

Aortic root rupture was associated with much poorer in-hospital outcomes (table 1). Within the ruptured group, outcomes were worse among patients with contained (n = 11) vs. uncontained (n = 20) rupture.   

Table 1. In-Hospital Outcomes

In patients who experienced rupture, multidetector computed tomography (MDCT) measurements showed a higher burden of LVOT/subannular calcification but not a higher prevalence of moderate/severe aortic cusp calcification. LVOT calcification was present below the right coronary cusp only in conjunction with rupture, whereas calcification below the left coronary cusp and non-coronary cusp was evenly distributed between rupture and control patients (table 2). 

Table 2. MDCT Results

Other measurements including annular size as well as sinus Valsalva maximum and minimum diameters, LVOT area, and annular eccentricity were similar between the 2 groups 

In addition, patients with aortic root rupture had a greater degree of area-based prosthesis oversizing (30.5 ± 15.8% vs. 11.3% ± 19.7%; P < 0.001) and higher frequency of post-dilatation (22.6% vs. 0; P= 0.005). 

Logistic regression analysis identified 2 predictors of aortic root rupture: 

• LVOT/subannular calcification (OR 10.92; 95% CI 3.23-36.91; P < 0.001) 
• Prostheses oversizing of 20% or greater (OR 8.38; 95% CI 2.67-26.33; P ≤ 0.001) 

Exercise Care When Oversizing

Aortic rupture is rare but stands out as “a particular concern with balloon-expandable prostheses due to the significant force applied during balloon deployment,” the investigators note, citing a cumulative LVOT/annulus rupture rate of 1.1% from a recent meta-analysis.   

Calcification in the LVOT appears to be a key risk factor, particularly when located below the right coronary cusp, they write. “While interesting and contradictory to traditional thinking, further study is needed to better understand how location of calcification may or may not impact the risk of annular injury from TAVR.”   

The severity of aortic valvular calcification, however, does not appear to be very influential, Dr. Leipsic and colleagues add, “perhaps because the calcified leaflets are generally accommodated within the capacious sinus of Valsalva.”   

Moreover, while a certain degree of oversizing can mitigate the risk of paravalvular regurgitation, patients with significant LVOT calcification might prove to be the exception, they advise. “This awareness may allow more patient-specific [transcatheter heart valve] selection through integration of MDCT data to allow the most appropriate valve choice with more modest oversizing (or even undersizing) of those patients with features that would predispose them to potential annular rupture through selection of a smaller valve size or balloon underfilling to control the degree of annular/LVOT stretch.”   

The results of this case-control study, while inherently limited, “are of valuable clinical relevance and may serve as an important starting point for larger cohort studies,” the researchers conclude.   

Note: Study coauthors Martin B. Leon, MD, and Susheel Kodali, MD, of Columbia University Medical Center (New York, NY), serve as faculty members of the Cardiovascular Research Foundation, which owns and operates TCTMD.   

  

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Source:
Barbanti M, Yang T-H, Rodés-Cabau J, et al. Anatomical and procedural features associated with aortic root rupture during balloon-expandable transcatheter aortic valve replacement. Circulation. 2013;Epub ahead of print. 

  

  

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