Patients with a small aortic annulus (a predominantly female population with a higher risk of prosthesis–patient mismatch) represent a particularly challenging subgroup within TAVI. Self-expanding valves with a supra-annular design have demonstrated better early hemodynamic parameters compared with intra-annular balloon-expandable valves, at the expense of a higher incidence of paravalvular leak and conduction disturbances. However, the long-term clinical impact of these differences had not been clearly established. The aim of this study was to compare five-year clinical and echocardiographic outcomes between balloon-expandable and self-expanding valves in patients with a small aortic annulus undergoing TAVI.
A retrospective analysis was conducted using the RESOLVE registry from Cedars-Sinai Medical Center (Los Angeles, United States), which included 1,392 patients treated between 2015 and 2020. Of these, 423 had a small aortic annulus defined by computed tomography (area <430 mm²). In this cohort, 345 patients received balloon-expandable valves and 78 received self-expanding valves. The median age was 82 years, 78% were women, and surgical risk was intermediate (median STS score 4.37%; IQR 2.87–6.70). Mean body surface area was 1.70 m², and left ventricular ejection fraction was preserved in both groups. The mean aortic annulus area was 381 mm². Contemporary commercial valves were used, predominantly sizes 23 and 26 mm in the balloon-expandable group, and 23, 26, and 29 mm in the self-expanding group.
The primary endpoint was a composite of all-cause mortality, stroke, or hospitalization for heart failure at five years. Secondary endpoints included myocardial infarction, permanent pacemaker implantation, valve reintervention, and structural valve deterioration, defined according to VARC-3 criteria.
Five-year outcomes of TAVI in small aortic annulus: superior hemodynamic performance with self-expanding valves
From a hemodynamic standpoint, self-expanding valves showed a sustained superior performance over time, with significantly lower mean gradients and a larger indexed effective orifice area. At 30 days, the mean gradient was 6 ± 2 mmHg in the self-expanding group compared with 12 ± 3 mmHg in the balloon-expandable group (p<0.001), a difference that persisted at five years (6 ± 3 mmHg vs 13 ± 4 mmHg; p<0.001). The indexed effective orifice area was also greater with self-expanding valves (0.9 ± 0.2 cm²/m² vs 0.7 ± 0.2 cm²/m²; p=0.025). However, self-expanding valves were associated with a higher rate of moderate-to-severe paravalvular leak (7.7% vs 1.5%; p<0.001) and a greater need for post-dilatation (25.6% vs 2.3%; p<0.001).
Regarding clinical outcomes, at five years the primary endpoint occurred in 39.7% of patients with balloon-expandable valves and in 41.1% of those with self-expanding valves, with no statistically significant differences (adjusted HR 1.65; 95% CI 0.88–3.09; p=0.11). All-cause mortality was comparable between both groups (24.9% vs 28.2%; p=0.09), as were the rates of stroke, myocardial infarction, rehospitalization for heart failure, valve reintervention, and structural valve deterioration, which remained low and similar (19.7% vs 15.4%; p=0.64).
The most clinically relevant difference was observed in conduction disturbances: permanent pacemaker implantation was significantly more frequent in the self-expanding valve group (17.9% vs 6.1%), with an adjusted risk more than four times higher (HR 4.03; 95% CI 1.90–8.54; p<0.001). Additionally, a higher incidence of early stroke at 30 days was recorded in the self-expanding group (5.1% vs 0.6%; p=0.002).
Conclusion: The hemodynamic advantage of self-expanding valves does not translate into better clinical outcomes
In conclusion, in patients with a small aortic annulus undergoing TAVI, self-expanding valves provide a sustained hemodynamic advantage at five years, with lower gradients and a larger effective valve area. However, this benefit does not translate into a reduction in major clinical events or improved survival and is offset by a higher incidence of paravalvular leak and, particularly, permanent pacemaker implantation. These findings support an individualized selection of prosthesis type, balancing hemodynamic performance and clinical risk in each patient.
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