Studies Zero in on Baseline Factors That Influence TAVR Outcome

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Two posters presented June 30, 2013, at the American Society of Echocardiography 24^th Annual Scientific Sessions in Minneapolis, MN, help to identify those who will respond poorly to transcatheter aortic valve replacement (TAVR). 

Anatomic Factors Predict Mismatch 

For the first study, researchers led by Philippe Pibarot, DVM, PhD, of Laval University (Quebec City, Canada), analyzed data on 2,211 patients with severe aortic stenosis enrolled in cohort A of the PARTNER trial. In all, there were 574 patients from the 2 randomized arms (n = 304 TAVR and 270 surgery) and 1,637 patients from the nonrandomized continued access TAVR registry.

Postoperative prosthesis-patient mismatch was categorized based on effective orifice area as absent (> 0.85 cm²/m²), moderate (0.65-0.85 cm²/m²) or severe (< 0.65 cm²/m²). 

The incidence of mismatch was highest in the surgery group at 60% (28% severe), followed by 48% (20% severe) in the randomized TAVR group and 43% (14% severe) in the nonrandomized TAVR group. In patients with aortic annulus diameter ≤ 20 mm, mismatch occurred in 34% of surgical patients, 19% of randomized TAVR patients, and 15% of nonrandomized TAVR patients. 

On multivariate analysis, independent predictors of moderate and severe mismatch within the randomized TAVR cohort were:

• Larger body surface area (P < 0.001)
• Smaller aortic annulus diameter (P= 0.03)
• Smaller cover index (based on discrepancy between device size and diameter; P= 0.002) 

Within the nonrandomized TAVR cohort, predictors were similar with the addition of younger age (P = 0.003). For surgery, predictors were larger body surface area (P= 0.014) and smaller aortic annulus diameter (P = 0.01).

Effective orifice area as a continuous variable depended on the same predictors in all 3 groups.

“TAVR may provide an interesting alternative to SAVR to prevent [prosthesis-patient mismatch] and its sequelae in patients with a small aortic root,” the researchers conclude, suggesting that a larger range of available prosthesis sizes and utilization of 3-D imaging may help reduce mismatch that arises from undersizing.

Echo Parameters Predict Regurgitation

The second study, by Rebecca T. Hahn, MD, of Columbia University Medical Center (New York, NY), and colleagues, looked at baseline echocardiograms of patients who underwent TAVR in the PARTNER trial, either in the randomized arms of cohorts A and B (n = 465) or the nonrandomized continued access registry (n = 1,757).

Echocardiographic parameters differed among patients who did and did not develop paravalvular regurgitation, with the most substantial disparities seen between mild or moderate/severe compared with no/trace regurgitation (table 1).

Table 1. Echocardiographic Parameters by Degree of Paravalvular Regurgitation

Patients with moderate/severe paravalvular aortic regurgitation also were more likely to have moderate/severe aortic or mitral regurgitation at baseline and to have received 26-mm vs. 23-mm valves. 

“These differences suggest that these patients may be at higher risk even before the development of [paravalvular leak] and may help explain, at least in part, the previously reported increased risk in mortality associated with mild [paravalvular aortic regurgitation],” the investigators conclude. “The association between increased mortality and these parameters should be investigated.”

Note: Martin B. Leon, MD, of Columbia University Medical Center and several other coauthors of the above abstracts are faculty members of the Cardiovascular Research Center, which owns and operates TCTMD. 

2. Hahn RT, Douglas PS, Pibarot P, et al. Differences in baseline echo parameters in patients with varying severity of paravalvular regurgitation following transcatheter valve replacement. Presented at: American Society of Echocardiography 24^th Annual Scientific Sessions. June 30, 2013. Minneapolis, MN.

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• Post-TAVR Coronary Obstruction Risk Low, Linked to Unfavorable Anatomic Features
• CT-Based Annulus Sizing Reduces Regurgitation After TAVR