Author + information
- Femi Philip, MD∗ (, )
- Garrett B. Wong, MD and
- Jeffrey A. Southard, MD
- ↵∗Department of Internal Medicine, Interventional Cardiology, Cardiovascular Medicine, University of California, Davis, 4860 Y Street, Suite 2820, Sacramento, California 95817
Transcatheter aortic valve replacement (TAVR) is an established therapeutic option for patients with severe symptomatic aortic stenosis. However, the periprocedural stroke rate continues to be relatively high, ranging between 3% and 5% in randomized clinical trials and large registries (1,2). Despite the evolution of the transcatheter valve, delivery system design, and procedural techniques, stroke rates have not diminished. Additionally, studies that have utilized diffusion-weighted magnetic resonance imaging have demonstrated a high rate of silent cerebral emboli upwards of 70% during TAVR (3). Although these findings may reflect, to some extent, the nature of TAVR in a high-risk patient with multiple comorbidities, this may also reflect a fundamental limitation of the procedure. In fact, transcranial Doppler studies during TAVR have highlighted the occurrence of cerebral embolization at virtually all of the time points during the procedure but seem most frequent during valve positioning and implantation, suggesting a mechanical interaction between the transcatheter valve and the native aortic valve. In particular, procedural variables suggest that mechanical factors such as balloon post-dilation, valve dislocation or embolization, or the need for a second valve are associated with a higher cerebrovascular event rate (4). Additionally, these studies have identified the lowest number of transcranial Doppler events occurring during balloon aortic valvuloplasty (BAV).
Given these considerations, we read with much interest the recent paper by Bijuklic et al. (5) in JACC: Cardiovascular Interventions evaluating the effect of TAVR without versus with prior BAV on the risk of cerebral embolization in 87 patients who received a balloon-expandable valve. Their procedural success rate was 93.5% with and 98.2% without BAV, and procedure duration and contrast volume were significantly lower without BAV. The incidence of new cerebral ischemic lesions in the total cohort was 66.7%. Compared with patients with BAV, those without BAV had a significantly higher total volume of cerebral ischemic lesions (235.4 ± 331.4 mm3 vs. 89.5 ± 128.2 mm3; p = 0.01) (5).
Despite the important findings of this study, there are some concerns that would limit the broader application of this study to a larger patient population. Despite the overwhelming association between various procedural variables during the TAVR procedure, the authors do not detail procedural variables with sufficient granularity to postulate a mechanism for their findings. Specifically, they do not mention the number of times the aortic valve is crossed, duration of the pacing run, implantation duration, degree of oversizing, number of inflations, need for post-dilation, extent of the aortic and aortic valve calcification, and activated clotting time in the 2 groups. A difference in the procedural variables may explain the lack of significant difference between the overall number of new cerebral ischemic lesions and the significant difference in the volume of cerebral ischemic lesions between the 2 groups.
Cerebral embolization and stroke will always be a concern during invasive aortic procedures. Now that the safety and efficacy of transcatheter valves are established, optimizing TAVR-related cerebrovascular outcomes is the next fundamental challenge that will determine the future role of this technology as we move to treat a younger and lower-risk patient subset. For now, is doing less more?
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2016 American College of Cardiology Foundation
- Kahlert P.,
- Knipp S.C.,
- Schlamann M.,
- et al.
- Bijuklic K.,
- Haselbach T.,
- Witt J.,
- et al.