A new study presented at the 2018 Society for Cardiovascular Angiography and Interventions (SCAI) Scientific Sessions (25–28 April, San Diego, USA) indicates 3D printing technology could be used to confirm and detect paravalvular leak following transcatheter aortic valve implantation (TAVI). Cardiovascular News spoke to Sergey Gurevich (University of Minnesota, Minneapolis, USA) about the study.
What percentage of patients will have an ill-fitting valve and what are the potential consequences?
It honestly depends on how you define “ill-fitting”. In my view, an ill-fitting valve is one that offers poor clinical outcomes. For example, many meta analyses and studies show that moderate or greater paravalvular leak—leak around the bioprosthetic valve due to a small size or calcium or poor fit—doubles a patient’s risk of all-cause or cardiac mortality, as well as their risk of hospitalisation at one year. However, paravalvular leak is not the only adverse outcome of an ill-fitting valve. Complete heart block or conduction disease requiring pacemaker placement is another and occurs in as many as 10–30% of patients, depending on the valve type used.
Historically, earlier generations of Sapien valves (such as Sapien XT, Edwards Lifesciences) have had higher paravalvular leak rates but lower pacemaker rates (5%), while other valves such as the Lotus (Boston Scientific) have had lower paravalvular rates at the expense of almost prohibitively high pacemaker rates (30%). Newer generations of these valves have developed various methods of trying to solve these problems. Edwards, for instance, have developed a “sealing skirt” around their second generation valve—the Sapien 3—that has dramatically reduced the rates of greater than mild paravalvular leak. Medtronic has attempted the same with their CoreValve Evolut Pro. Additionally, the shorter profile of the new Lotus valve will hopefully reduce their pacemaker rates to that of other valves (like the latest generations of Sapien and CoreValve).
Prior to your study, what evidence was available for the use of 3D models for sizing bioprosthetic valves?
The majority of current available data for 3D printing and computer simulations in preprocedure planning for TAVI comes from either case reports or small cohort observational studies of 10–20 patients. There is only a handful of these studies currently in the literature.
What were the aims of your study?
Our aim is to see if we can predict paravalvular leak in patients with TAVI prior to implantation of the valve. To do this, we selected 20 patients out of more than 300 that had undergone TAVI at our institution and used their preprocedure multislice computed tomography (CT) images to print 3D models of their aortic root. Sapien TAVI frames were then implanted into these 3D models, which were then scanned using CT and those digital models were further evaluated for paravalvular leak. Identified paravalvular leak in those models was then compared with both preprocedure CT images as well as post procedure transthoracic echocardiogram (TTE) or transoesophageal echocardiography (TOE) images to identify if the leak on our models matches any identifiable structural problems on CT and Doppler evidence of paravalvular leak. In each case, our paravalvular leak matched what was seen on post procedure TTE/TOE and closely matched calcium location on preprocedure CT. This is also the first 3D printed study using Sapien valves; all prior studies have used self-expanding valves (CoreValve).
What were the key findings of your study?
We found that 3D printing preprocedure can identify areas of paravalvular leak and that 3D printing can identify aetiology of paravalvular leak.
What are the implications of your study for TAVI?
3D printing preprocedure can identify those patients at risk for paravalvular leak, which can assist in the selection of the right valve size and valve type for that particular patient.