Anatomical Characteristics of Patients with Symptomatic Severe Aortic Stenosis in China

Transcatheter aortic valve replacement (TAVR) has emerged as a transformative treatment for severe aortic stenosis (AS), particularly in patients deemed high-risk for surgical intervention. As TAVR adoption expands globally, it has become evident that patient populations differ significantly across countries in terms of age, body habitus, disease etiology, aortic valve morphology, and anatomical dimensions. In China, the average age of TAVR patients is approximately five years younger than in industrialized countries, making the Chinese population a valuable predictive model for future TAVR trends in younger patients worldwide. However, detailed anatomical characteristics of Chinese patients, particularly those derived from multislice computed tomography (MSCT), remain underexplored. This study aims to address this gap by providing a comprehensive analysis of the anatomical features of Chinese patients with symptomatic severe AS undergoing TAVR screening.

Study Design and Patient Population

This retrospective analysis included data from 54 centers across China, focusing on patients with native severe AS evaluated for TAVR using the first-generation domestic device, the Venus A-Valve (Venus MedTech Inc., Hangzhou, China). The study was conducted under the framework of the China Aortic valve tRanscatheter Replacement registrY (ChiCTR2000038526). The Venus A-Valve, the first commercially approved transcatheter aortic valve in China, holds the largest market share, ensuring that the patient population in this study is representative of the broader Chinese TAVR candidate pool. All patients provided consent for anonymized data acquisition and analysis, and the registry was approved by institutional ethical committees.

The study enrolled 2,097 patients with a mean age of 73.2 ± 7.6 years, of whom 58.4% were male. The cohort was geographically diverse, with patients from Northern China being the oldest. Bicuspid aortic valve (BAV) morphology was identified in 54.0% of the cohort, with subtypes classified according to the Sievers system. Specifically, type 0 BAV accounted for 42.5% of BAV cases, type 1 for 34.6%, type 2 for 1.8%, and partial-fusion BAV for 20.6%. Quadricuspid aortic valve was rare, occurring in only 0.2% of patients. Regional variations in BAV prevalence were notable, with Central China exhibiting the highest proportion (63.4%) and Northern China the lowest (45.8%).

Anatomical Measurements and Findings

Aortic Annulus Dimensions

The aortic annulus perimeter was measured using MSCT, with 0.1% of patients falling below the lower bound (53 mm) and 7.4% exceeding the upper bound (91 mm) of the Venus A-Valve sizing chart. BAV patients exhibited a larger aortic annulus area compared to tricuspid aortic valve (TAV) patients (477.5 ± 112.7 mm² vs. 451.2 ± 177.9 mm², p < 0.001), but the annulus shape was less elliptical in BAV patients (eccentricity: 21.7 ± 8.4% vs. 23.1 ± 7.0%, p < 0.001). Type 0 BAV patients had a smaller annulus perimeter (75.98 ± 9.10 mm vs. 80.60 ± 8.90 mm, p < 0.001) and less elliptical annulus (eccentricity: 19.9 ± 9.2% vs. 23.2 ± 7.6%, p < 0.001) compared to type 1 BAV patients.

Calcification Burden

The mean volume of calcification within the aortic root was 550.2 mm³, with 15.4% of patients exceeding 1,000 mm³ and 22.3% having less than 150 mm³. BAV patients demonstrated a significantly higher calcification burden than TAV patients (558.7 [269.4–932.5] mm³ vs. 263.3 [95.9–536.7] mm³, p < 0.001). Type 0 BAV patients had less calcification than type 1 BAV patients (576.0 [298.6–943.8] mm³ vs. 641.7 [313.1–1008.9] mm³, p < 0.001). Regional differences in calcification burden were also observed, with Central China exhibiting the highest levels (583.0 [203.4–1180.0] mm³) and Eastern China the lowest (239.3 [67.9–560.0] mm³).

Coronary Ostia and Horizontal Aorta

The height of coronary ostia was less than 10 mm in 14.2% of patients, which may pose challenges for TAVR procedures. A horizontal aorta, defined as an angulation between the plane of the aortic annulus and a horizontal reference line greater than 60°, was identified in 23.3% of patients. This anatomical feature can complicate device delivery and positioning.

Access Vessel Dimensions

In patients planned for transfemoral TAVR, 23.6% had a main access vessel diameter of less than 6 mm, which may necessitate alternative access routes or specialized techniques to ensure successful device delivery.

Regional Variations in Aortic Root Anatomy

Significant regional differences in aortic root dimensions and calcification burden were observed across China. Patients from Northern China exhibited the smallest anatomy at the annular, sinus, and sinotubular junction (STJ) levels, while those from Western China had the most dilated ascending aorta. These variations may reflect differences in genetic, environmental, and lifestyle factors across regions.

Comparison with International Data

The study compared its findings with seven previous reports from different geographical backgrounds. Notably, Chinese patients exhibited a higher prevalence of type 0 BAV (∼40% vs. ∼12%) and a greater calcification burden (∼680 mm³ vs. ∼350 mm³) compared to international cohorts. These differences highlight the need for tailored TAVR strategies and device designs to address the unique anatomical characteristics of Chinese patients.

Clinical Implications

The high prevalence of BAV morphology, particularly type 0, in Chinese patients poses specific challenges for TAVR. Type 0 BAV, characterized by the absence of a raphe, complicates the determination of the virtual annulus and is associated with higher rates of mean transprosthetic gradient ≥20 mmHg. The elevated calcification burden in Chinese patients also raises concerns, as aortic root calcification is a known risk factor for paravalvular leak, pacemaker implantation, and device success. Chinese domestic devices, such as the Venus A-Valve, have been designed with increased radial force to optimize valve expansion in calcified anatomies. However, further research is needed to evaluate the clinical benefits of these devices compared to more conformable alternatives.

Regional differences in aortic root anatomy and calcification burden within China underscore the importance of considering local epidemiological factors when planning TAVR procedures. The observed variations may influence device selection, procedural planning, and patient outcomes.

Limitations

The study has several limitations. Its retrospective design introduces the potential for selection bias among enrolled patients and participating centers. The analysis relied solely on MSCT data, precluding the grouping of imaging findings by the severity of aortic regurgitation or correlation with clinical outcomes. Additionally, the core laboratory did not track clinical decisions at each site, making it impossible to determine the rejection rate for TAVR after anatomical evaluation. Errors in subclassifying partial-fusion BAV and the lack of fusion pattern data for type 1 BAV further limit the study’s comprehensiveness.

Conclusion

Chinese patients with symptomatic severe AS exhibit unique anatomical characteristics, including a high prevalence of type 0 BAV morphology and a greater calcification burden compared to international cohorts. Regional variations in aortic root dimensions and calcification burden within China further highlight the need for tailored TAVR strategies. These findings underscore the importance of including Chinese centers in international TAVR trials to ensure a broader representation of patient anatomies. Additionally, the Chinese medical community may benefit from adapted TAVR strategies and device designs that address the specific challenges posed by these anatomical distinctions.

doi.org/10.1097/CM9.0000000000001863

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