Significant aortic angulation, commonly referred to as a “horizontal aorta,” has historically been regarded as a challenging anatomical feature in TAVI because it may hinder coaxial alignment of the delivery system and compromise implantation results. Much of this concern stems from studies performed with earlier-generation devices and from dichotomous definitions based on arbitrary cut-off values, with an aortic angulation >48° classically considered clinically relevant.
Within this framework, Polat et al. report a single-centre study conducted at a highly experienced German tertiary referral centre (Augsburg University Hospital), including 509 consecutive patients with severe aortic stenosis treated with transfemoral TAVI between 2021 and 2024. Aortic angulation was assessed by computed tomography using 3mensio® software and analysed as a continuous variable. The primary endpoint was device success according to VARC-3 criteria. Secondary endpoints included technical success, 30-day early safety, fluoroscopy time, contrast volume, paravalvular regurgitation, and permanent pacemaker implantation.
The study population had a mean age of 80 years, a mean EuroSCORE II of 4.2%, and a mean aortic angulation of 48.1° ± 8.2°. A total of 337 (66%) balloon-expandable TAVI prostheses and 172 (34%) self-expanding TAVI prostheses were implanted, representing a 2:1 ratio. Device success was achieved in 89.4% of cases and technical success in 96.3%, with no significant association between aortic angulation and early clinical outcomes. Likewise, no relationship was found with higher rates of paravalvular regurgitation or permanent pacemaker implantation.
However, greater angulation was significantly associated with longer fluoroscopy time (4.4 seconds per degree of angulation, p = .006) and higher contrast use (0.4 mL per degree of angulation, p = .037), reflecting greater technical complexity during the procedure. These findings were consistent in both balloon-expandable and self-expanding prostheses.
In conclusion, the study suggests that, with contemporary devices, aortic angulation does not impair early clinical outcomes after TAVI, although it does lead to increased procedural resource utilization.
COMMENTARY:
For years, aortic angulation has been one of the anatomical factors generating the greatest concern in transcatheter aortic valve implantation. In the past, the so-called “horizontal aorta” was linked to poorer procedural performance, with greater difficulty achieving coaxial alignment, a higher likelihood of prosthesis malposition, and more paravalvular regurgitation. However, most of that evidence came from studies performed with older valve platforms and delivery systems that have now been technologically surpassed.
The study by Polat et al. provides a contemporary and methodologically appealing perspective by assessing angulation as a continuous variable rather than relying on arbitrary cut-off values, since common sense would suggest that the greater the angulation, the worse the outcomes should be. In addition, the analysis focuses exclusively on patients treated through the transfemoral route with new-generation prostheses, which likely represents the most relevant population in current clinical practice.
The findings are somewhat unexpected because they challenge a long-standing assumption: aortic angulation was not associated with worse clinical outcomes. Device success, technical success, 30-day safety, and relevant complications such as paravalvular regurgitation or permanent pacemaker implantation were not influenced across the full range of angulation values. This contrasts with earlier reports and suggests that technological progress has substantially attenuated the impact of this anatomical variable.
That said, several relevant aspects of the study deserve closer consideration. First, the actual angulation distribution within the cohort limits the generalizability of the results. With a mean value of 48.1° ± 8.2°, nearly half of the patients did not truly have a “horizontal aorta,” as they fell below the historical threshold of 48°. In addition, the authors themselves acknowledge that extreme angulations (≥70°) were clearly underrepresented, with only 7 cases (1.4%). As a result, the study mainly reflects anatomies of low-to-intermediate complexity. This reduces statistical power and introduces selection bias, which may help explain the absence of a significant clinical effect.
Second, the cohort was not balanced with regard to prosthesis type. Two-thirds of patients received balloon-expandable valves, whereas only one-third were treated with self-expanding platforms, which are precisely the devices historically thought to perform less favourably in this anatomy. This imbalance may have reduced the ability of the study to detect differences within the self-expanding subgroup, which is arguably the most informative group to evaluate. Furthermore, the main text does not specify the implanted brands or individual device models. This is particularly relevant because meaningful differences exist among contemporary systems, such as Evolut® PRO/PRO+ and Acurate Neo2®, where final valve positioning depends not only on intrinsic prosthesis characteristics but also on the navigation and delivery system.
Comparison with the previous literature is also essential. In the landmark study by Abramowitz et al. in 2016, angulation ≥48° was associated with worse outcomes exclusively in self-expanding prostheses, whereas balloon-expandable valves showed stable performance. That study, as well as others from the same period, was conducted with CoreValve® and Sapien/Sapien XT® devices, older platforms with stiffer delivery systems and less repositioning capability. It is plausible that improvements incorporated into modern valves, including greater flexibility, recapturable systems, and more effective sealing mechanisms, have substantially reduced the adverse effect of angulation observed in earlier eras. This effect may have been further diluted by the fact that the present study was conducted in a high-volume centre with experienced operators, which could also have made it harder to detect outcome differences.
On the other hand, the study clearly shows that greater angulation translates into longer fluoroscopy times and higher contrast consumption in a directly proportional manner. Yet, when the true magnitude of this effect is examined, the clinical impact appears modest. For each additional degree of angulation, procedural duration increased by only 4 seconds and contrast use by 0.4 mL. In other words, even in the most angulated cases, the practical consequence is an increase of approximately 2.2 minutes and 12 mL of contrast, which is unlikely to be clinically meaningful. This is further supported by the absence of a significant difference in total procedure time, which remained around 60 minutes across the full angulation spectrum. In daily practice, marked aortic angulation may simply mean spending an extra minute obtaining one additional fluoroscopic projection to optimize commissural alignment, without materially affecting the final duration of the intervention. Procedure time is influenced by many other factors. Some patients may not have challenging angulation but may present more complex femoral access, whereas others may show the opposite pattern. Ultimately, these interacting factors are what determine the total duration of the procedure.
In conclusion, this study reinforces the concept that, in the contemporary era, aortic angulation alone does not dictate procedural outcome. At the same time, it should not be interpreted as a completely irrelevant variable. These data are not sufficient to dismiss its role entirely, and it still seems reasonable to consider angulation a risk modifier in cases of very extreme anatomy, such as ≥70°, or when other unfavourable anatomical features coexist, as it may anticipate greater technical difficulty. In this setting, modern self-expanding valves have clearly evolved and have probably overcome many of the limitations described in the past. Even so, from a practical standpoint, when the anatomy is markedly horizontal, balloon-expandable prostheses still offer theoretical advantages in terms of coaxiality and deployment control, which may make them preferable in selected patients.
Ultimately, rather than deciding which valve to use based solely on angulation, the current message is to integrate angulation into a comprehensive anatomical assessment that also considers annular size, coronary height, calcification burden, and pacemaker risk, thereby allowing the TAVI strategy to be individualized and optimized for each specific anatomy.
REFERENCE:
Polat E, Fortunato A, Schemet L, Friedrich-Welz S, Tomsic A, Amer M, Girdauskas E, Owais T. Increased Aortic Angulation in Transcatheter Aortic Valve Implantation-Still a Challenging Anatomy? Interdiscip Cardiovasc Thorac Surg. 2025 Dec 1;40(12):ivaf281. doi: 10.1093/icvts/ivaf281.
